Storm Chaser and Meteorology Student Ryan Alliss

Slow transition to own website

2011-07-04T00:55:00.001-05:00

Currently developing another website on my own space, check it. This page will no longer reason forecasting updates.

ryanalliss.com

April 9th Highlight Video

2011-06-24T16:22:00.000-05:00

Severe July Continues

2010-07-16T00:45:00.002-05:00

Hello everyone,

Another severe day passes in July and surprisingly another presents itself only a few days later. The storm prediction center in Norman has issued a Day 3 slight risk for the northern half of Iowa into Minnesota. The probability is a 30% hatched risk. This is significant as day 3 outlooks rarely have such high probabilities. This means SPC is very confident in a severe weather outbreak in this area.

Currently the threat looks marginal to me. The upper level winds are just passed borderline, low level wind shear is not all that great, a strong cap appears to dominate, and high lcl heights look to be present. At this moment I would say the tornado threat looks poor. Large hail and damaging winds from higher based supercells and a squall line are much more likely.

Tomorrow's model runs will clear things up, I am happy to see SPC did not upgrade the day 2 risk to moderate as the models do not support this.

Another post will come late tomorrow night.

Strong Tornadoes in July?

2010-07-14T10:04:00.003-05:00

Greetings,

An unusually strong system has dug into the northern United States today bringing with it a good chance for organized supercells capable of producing tornadoes. The main threat for tornadoes appears to be in SE MN into SW WI where a good combination of strong instability and high low level wind shear exists.

July normally is a quite month for tornadoes as the warm summer heat helps push storm systems north into Canada where less juice is present which suppresses any large tornado threat. Occasionally, large, deep systems will form that may dig far enough south that may bring organization. This is exactly what is happening today. In order for supercells to be present winds at around 30,000 ft need to be at least 35 kts, otherwise it has been shown that multicell storms with a lack of organization are favored. When these storm systems dig far enough south, winds aloft speed up and help generate the threat.

The storm prediction center currently has a moderate risk for severe weather for the region I mentioned. The tornado probabilities are high with a 15% hatched, meaning that you are 15% likely to see a EF2 or higher end tornado within 25 miles of a point in that region. Rumors are out saying that SPC will upgrade their risk to high by 1pm today.

I think the moderate is warranted as parameters are lining up, but my main concern is whether or not these storms will stay discrete, or separate and alone from each other long enough to give a storm the chance to spin something up. Being as this chase would send me further east from home as I chased and that the target is already far to my north I have decided to sit this one out as I do not think this setup is good enough. The parameters are good, but not $60 worth of gas good.

My friends from Minneapolis will be chasing today and will be streaming live for WeatherNation on ustream here:
http://www.ustream.tv/channel/chase-weathernation

0-1km EHI, Tornado Potential.

Blogger mobile test

2010-07-13T18:05:00.001-05:00

test using Blogger android app

Published with Blogger-droid v1.4.6

Severe Weather Season Over?

2010-06-27T19:23:00.002-05:00

The end of June is approaching and with that the official season for storm chasing ends. It appears the last few days of June will be sunny and warm throughout all of tornado alley with only weak thunderstorms being a risk. With that being said I figure I would reflect on this years chases as a whole.

The beginning of the season was a rough one with most chases being cap busts in and around Iowa with only one exciting day with a supercell that went north of Cedar Rapids. At the time, I feared that either Iowa or myself was cursed not to see tornadoes. I had been on nearly my 12th chase and not see anything.

All this changed as I with three other friends, drove all the way down to Oklahoma to chase my first high risk where I saw my first "maybe" tornado. It was quite a day and well worth the trip.

A month later I joined TWISTEX and saw three tornadoes in Texas and a number of other Supercells in Colorado. Also I got to experience some insane lightning shows as well as holding a hailstone that was around 4 inches in diameter.

My time with TWISTEX expired on June 15th, and two days later the chase of my life happened. On June 17th I witnessed over 10 tornadoes in northern Iowa and Southern Minnesota. One of those tornadoes was rated EF-4 and a few others rated EF-3. It certainly was an amazing day and counts as the first chase that I had no professional guidance where I saw a bonified tornado. It was truly a surreal day and scary to see how powerful storms can be when the right conditions line up.

I chased at least two more days after this chase and witnessed some squall lines and crappy storms, even though SPC had at least a 5% tor prob on each day.

My impressions and thoughts that go into a chase have changed dramatically. Forecasting seems to be somewhat easy anymore, the problem is will the weather cooperate and do I have the resources (mainly money) to get to where I need to go. Not to say I get my forecasts right all the time, as many cap busts have proven that, but it appears that from what information I'm given, from models and spc, we go to where we need to when the risk is warranted. I can thank TWISTEX, upperclassmen, and my friends for building my forecast skills while chasing.

My wish list for next year would be to fix my car, get a hd camcorder, and work on saving up money this winter for chasing expenses beforehand. Next year I hope to be able to expand my chase domain as Iowa seems to really screw us all over. I also hope to bring along more people other than chasing buddies so they too can experience chasing, as what I am doing is just as good as what the tour groups do, I am just a lot cheaper ;-).

With the big outbreak in Minnesota I found an avenue to make some money off of chasing. My youtube video was quite a hit and I was offered to put ads on my channel and from that make money. Currently this money is very little and will not pay for chasing, but if I can get quality video at a close range and often, my channel may take off. I am considering this, but not taking it too seriously as I do not want to turn into a pro chaser, nor do I have an interest to do so. Easy money is just hard to turn away.

Enough reflections, let me talk about discuss the next few weeks for weather.
It appears that Iowa will be under a ridge of high pressure until the beginning of July which means warm sunny conditions with temps in the 80s. The humidity will be tolerable and hopefully we will not be seeing 70 degree dewpoints for the next few weeks.

The next chance for some showers and thunderstorms appears to be around the 4th where the models indicate both a trough and current tropical storm to approach our area. Any severe weather most likely will be confined to the Dakotas, especially if Iowa is affected by the tropical system. This could mean heavy rains in Iowa if this pans out, certainly something to watch since it will be near the 4th.

Thanks for reading!

Will begin posting again

2010-06-21T23:58:00.002-05:00

Hello everyone, I will be posting to my blog more often now, I have been distracted from a few things, but to help me with my forecasting and to inform all of you I will continue posting.

Thanks!

Review of May 10th, 2010 Chase

2010-05-13T00:17:00.009-05:00

Overview
We left Ames around 6 am for our target area being northern Oklahoma with a preliminary target of Ponca City, OK. We arrived in northern Oklahoma approximately around 2pm and decided to head west to Pond Creek. A tornado watch was soon issued thereafter. The first storm initiated within the next hour west of us so we headed west just south of Cherokee, OK. The storm track began to shift to the south so we decided to go back the way we came and target just north of Medford, OK. The storm dropped the multivortex tornado to our west while en-route. North of Medford we waited for the storm base to become visible as a hill was blocking our view. Radar suggested that the circulation was headed right for us so we headed back south and saw the large circulation to our west shown in the video. This is being termed the "Medford Wedge" tornado. The tornado became wrapped in rain quickly and as we moved east we lost visual. On the video near the end a funnel cloud was observed behind the main circulation.
We went NE to stay with the storm but road construction, chaser convergence, and lack of visibility forced us to target a different storm to the south. Unfortunately where we turned off the storm later produced an EF-3 tornado and was documented by a weather channel meteorologist. We went to Ponca City and try to sneak in from the backside of the supercell but by the time we entered the updraft the circulation had weakened and the tornado had died, only a few chasers saw this tornado. We followed this storm to the NE and observed rotation in the cloud and apparent wall cloud formation and dissipation, but no funnels.
We left this storm for another supercell that seemed to be organizing to our north. We intercepted this and observed rotation in the cloud base but once again no funnels or tornadoes. We were in Kansas by this time and the storms were all beginning to lose organization so we called it quits in Independence, KS. We arrived back in Ames that night around 2 am.
A map of our route, interest points, and the Medford tornado and Ponca City tornado tracks are shown below (Click double arrows to hide left toolbar details):

Multimedia
Video

Pictures

Storm relative velocity, bright red and greens are the tornado, white circle with dot in the middle is our location, very close

Updraft, towering cumulus, taken just before the tornado was visible north of Medford

Radar when tornado was on the ground south of Ponca City, we were north of the cell as shown by white circle, waited for it to past to our east instead of punching through the core of rain and hail

Radar of the Medford/Wakita tornado as it was producing the multi-vortex tornado, we were north of Medford at the time waiting for it to approach, in perfect position as shown by white circle

The Medford wedge tornado, best image I got of it and this was just before the video was taken, it appears that the circulation was weaken as the video went on

Evaluation
Forecasting/Target City Location:
Excellent,
Our location where we sat was within 10 miles of the Medford tornado, we were the first few chasers on that supercell, played the setup perfectly

Chasing
Okay,
We saw a tornado and three beautiful supercells, that was great. However, I think we played the storms a little too conservatively because of the massive amount of chasers and the chance of giant and violent tornadoes. We could have stayed just north of Medford instead of moving east quickly to get a better view of that tornado and we could have seen the multi vortex tornado and the Ponca City tornado if we would have been more aggressive. We played this safe which was for the better.

Final Thoughts
I'm happy I finally bagged my first tornado, who would of thought I would have to drive to Oklahoma to see it! The storms that day were amazing and almost textbook in appearance on radar. It truly was a spectacular site and the puzzle that is chasing is so much fun. I cannot wait to chase with TWISTEX in June, let's just hope the weather cooperates.

Updates on Today's Chase

2010-05-10T08:25:00.001-05:00

Hello all,

You can receive updates from today's chase here:

https://twitter.com/Alliss_Chase

I will post as much as possible on there.

Update Regarding Chase on Monday

2010-05-09T22:58:00.002-05:00

Hello all,

I wanted to wait until the 7pm model runs came in before posting this as this will be the last real information about tomorrow until 10 am when the next model run is available. This is by far the most exciting chase that I will be a part of. The latest model runs indicate that very strong supercell thunderstorms capable of dropping violent tornadoes will be possible in north-central Oklahoma and south-central to south-eastern Kansas.

Forecast parameters that I use for forecasting severe weather are all off the charts in this region. I will go through the three main categories for severe weather forecasting now:

1) Instability (Energy for storms)
CAPE, a measure of instability, will reach to nearly 2500 J/kg in this area, 1500 is the threshold. This is a moderate value for CAPE, but as we will see later, the large wind shear will make up for it.

LCL Heights will be low, research has shown low lcl heights may lead to large and violent tornadoes, basically lcl heights are how low the cloud base is.

2)Lift (Helps erode a cap on storms)
A dryline will be located from central Kansas through Oklahoma and Texas. Along with the upper level trough, strong forcing will help initiate storms and erode the cap. The cap holding appears to be the only thing to worry about, but it appears very unlikely it will hold considering how much lift will be in place.

3)Wind Shear (helps produce rotation in storms)
Like my previous post said, the wind shear is phenomenal. Overall 0-6km shear is nearly 70 kts, 40 is the threshold for the formation of supercells.
The low-level wind shear is by the far the most impressive thing for tomorrow. 0-1km SRH will be over 400, 100 is the threshold. Most violent tornadoes had srh values of over 300. SRH is low level shear that is the most popular forecast tool with forecasting tornadoes in a good thermodynamic area.

With the moderate instability and extreme wind shear, intense supercells should erupt. I will mention a few parameters that list out the overall tornado threat and their threshold values
EHI- 10, threshold 3
Sig Tor- 8, threshold 2
0-1km VGP- .9, threshold 2

Currently our plan is to go the border of Oklahoma and Kansas and edit our chase location from there. We are leaving between 6 and 7 am.
My current position may not work tomorrow as it is giving me problems.

Severe Threat Monday, Chase Likely

2010-05-08T15:44:00.003-05:00

Hello all,

This first week of May has been rather uneventful in terms of severe weather but it appears things are about to ramp up come Monday. A negatively tilted trough will make it's way into western Kansas around 7pm putting the eastern half of Kansas into northern Oklahoma into a region of strong dynamical lift. A weak cap, if present, will be easily eroded away due to the strong lift in that region.

Instability looks to be decent, but is conditional based on how much moisture can make into Kansas and whether the convection earlier in the day to the east will leave quick enough to allow maximum day-time heating. The latest model runs suggest CAPE to reach to nearly 3000 J/kg south of Wichita, KS along the Oklahoma-Kansas border. A fairly narrow region where the cap is weak enough also exists in this area and as mentioned before with the strong dynamics, it should be eroded. This will occur between 4 and 7pm giving us 2-5 hours of good chase conditions.

Wind shear looks phenomenal and is very favorable for supercell thunderstorms that have the ability to drop large and violent tornadoes. 0-6km Shear is over 70kts, 40 is the baseline. 0-1 SRH is nearly 300 m^2/s^2, 100 is the baseline. Such large values of shear worry me in that storm motions will most likely be large too, it appears storms will be moving to the NE at around 40kts, pretty quick.

The moderate values for instability, collocated with the large wind shear will make for a quite a show Monday evening in southern Kansas. If I do end up leaving, my group of 4 will leave around 7am Monday and head for Wichita. The only real negative for such a long travel, is that Ethan and myself have to work the next morning which means we will have to drive back to Ames that night. Realistically, we would be back in Ames by 6am. This means that we may be on the road for almost 24 hrs straight, which I am not looking forward too, but hopefully it will be worth it.

An update will be posted tomorrow.

Model Output for Monday evening:

0-3km EHI (Severe Threat Parameter)

MLCAPE (Instability)

0-1km SRH (Low-level wind shear)

Monitoring High Risk #3

2010-05-01T16:03:00.003-05:00

The storm prediction center just issued a tornado watch for the eastern half of Arkansas. This tornado watch is a "particularly dangerous situation" watch, which means that probabilities for more extreme and long lasting severe weather are more likely.

Many chasers are currently just southeast of Little Rock, AR waiting for storms to go up including TWISTEX and other famous chasers. Most of them are sitting and wait for storms to go up in the Stuttgart and Pine Bluff area. A boundary where convection should be triggered is just to their northwest and seems to be stalled out. Within the next few hours the cap should break and storms should fire.

These storms will be more than likely be supercell storms as this airmass very unstable with mixed layer CAPE values of around 2000, overall shear values favorable for supercells storms, and low level helicity values approaching 300. All three of these, when collocated with each other, are very favorable for long-lived and violent tornadoes.

The only thing that could break this would be if the cap held, but that appears very unlikely as surface temps and dewpoints are very close to break the cap, LFC heights also have dropped significantly which implies the cap is about to break. I would expect storms to go up around 5pm south of Little Rock, AR.

I think the high risk is warranted, but they should have edited the outline as it appears to be too far west, past the boundary where storms will not fire. The weather channel is going crazy as well with Dr. Greg Forbes issuing his 9/10 tor con index for Arkansas, meaning a 90% chance of seeing a tornado within 50 miles, that seems a little extreme to me, but I'm not aware of what goes into his index.

As I am typing, one storm southwest of Little Rock just fired, but it appears to be going behind the boundary which should limit the storm's ability to drop a tornado. It doesn't appear chasers are being "baited" in by this initial storm.

Significant Tornado Parameter

SPC Tornado Probabilities

Doppler Radar @ 4:30pm

Storm Chase Tomorrow, Many Worries Present

2010-04-29T00:46:00.003-05:00

Much uncertainty has been present with the models over the last few days. This has made deciding a target location very difficult and really has made me rethink about even going out in the first place. Nonetheless, I did take work off and really would like to spend my Thursday chasing to relax after a fairly busy week. I will mostly likely go out even if I just end up chasing a squall line. I tend to be much more pessimistic overall, but when it comes to storm chasing I am very much an optimist. I really would hate to hear that a tornado touched down in Iowa and I wasn't chasing.

So what are my worries? Moisture appears to be hard to come by and the models believe that 60 degree dewpoints should be well into Iowa by 4pm which to many people seems unrealistic. My view is that if all the models are saying this will happen, it mostly likely will happen. I know it sounds ridiculous considering current dewpoints are in the mid 40s, but its hard to argue with multiple computer models.
Secondly winds appear to favor much more of a squall line type event, especially in the NAM forecast model. The other main model, the GFS, shows more of a SE wind at the surface which increases directional shear which would increase the tornado threat significantly. This is one of those wait and see until tomorrow setups. Hard to say what will actually happen. There still appears to be just enough low level shear in both models for tornadoes before the main squall roars to the east.
Finally a potential for a cap bust exists as 700 mb temps will be fairly high. Both models show the cap barely breaking between 4 and 7pm. This year the models have done a poor job at having the cap erode when in reality it didn't. This certainly worries me as I am tired of watching non-stormy skies. One of the most frustrating things in chasing is watching blue skies until dark. Let's pray this does not happen tomorrow.
The only consistent parameter from model run-to-run has been CAPE which has been in the range of 1000-2000. This will be favorable for tornadoes if collocated with enough low-level shear.
I have class till 2 tomorrow and will depart soon after. Currently my target area would have to be along I-80 just north of Atlantic, IA. This may change as the models have been jumping the system further east and west every run.

SPC Tornado Probabilities

Significant Tornado Parameter

407 Paper on Mesovorticies, Severe Threat Thursday

2010-04-26T02:37:00.006-05:00

I have been working hard on my semester paper for meteorology 407, mesoscale meteorology, this weekend. The paper is over mesovorticies within squall lines. This vorticies are basically low level circulations along the line that have been attributed to forming weak tornadoes. They are difficult to detect on radar and pose a serious threat to life as they may enhance straight line winds as well as the tornado threat. I worked with my partner, Matt Hoffman on this project.
The full paper, not in final form, can be accessed here:

Mesovortice Paper

As for the severe threat Thursday, things look very conditional based on instability. SPC did have a day five outlook circled over the central part of the country just south of Iowa, but today they removed it saying that they were uncertain about the timing of this event. The GFS model keeps changing it's mind on when and where the trough will be located Thursday around peak heating. From my perspective the dynamics will still be in place over Iowa to provide a severe threat.

Unfortunately instability will be very hard to come by in Iowa come Thursday. Model temperatures will reach the mid 60s and dewpoints will struggle to reach 55. This will lower instability tremendously even though the warm front appears to be into southern Minnesota come 4pm Thursday. It seems that a large of area of high pressure centered over the Gulf of Mexico in the next fews days will limit moisture transportation into Iowa, making the surface winds more southwesterly. This will advect in more of the dry air from Mexico rather than the juicy Gulf of Mexico air. It will finally move east come Wednesday but this will help little as more time is needed to advect in plentiful moisture for a favorable unstable environment.

Kansas, Oklahoma, and Missouri look to be in the best area for severe weather on Thursday. Some CAPE does make its way into eastern Nebraska and western Iowa which gives me some hope, only marginal CAPE is needed considering wind shear will be great.

I did manage to get Thursday off if needed, so I will be chasing if the threat is far enough north.

The Yazoo City tornado is currently rated an EF-4, but this is preliminary and may be bumped to EF-5, the weather service made it sound like this particular tornado was on the ground for a very long time which makes assessing its rating very difficult and time consuming. Its good (or maybe not considering the damage and many deaths) to see radar observations being confirmed by the ground damage.

As for tomorrow, a short wave trough will be moving through western Iowa with very cold air aloft. Precip type should stay in the form of rain, but the GFS model shows some 850 mb temperatures around 7pm Monday in far SW Iowa below 0 meaning that some snow may fall around then. The weather service is not mentioning flurries in their forecast. Overall the chance of seeing snow is extremely low, nonetheless it is interesting the atmosphere neared the threshold.

Updates regarding Thursday will come soon.

Imagery
GFS Forecast for CAPE, Thursday at 7pm

GFS Forecast for 0-1km SRH (Low Level Shear), Thursday at 7pm

Review of Severe Weather on April 24th

2010-04-25T00:21:00.003-05:00

I take back what I said from the previous post, SPC nailed it. Numerous tornadoes formed throughout Missouri, Mississippi, Alabama, and Tennessee. One supercell thunderstorm tracked from eastern Louisiana all the way into Alabama dropping numerous tornadoes. One of those tornadoes in particular was a very large and dangerous tornado that went through the town of Yazoo City.

I woke up around noon and pulled up radar immediately as SPC hinted at early surface based storms meaning that the tornado threat could be as early as around 1pm. This happened to be even earlier as tornadoes were on the ground prior to noon. The first image I looked at was as it was near Yazoo City and I have to say the signatures rank in the top 3 in terms of scariest radar signature. Gate to gate velocity was over 150 knots which indicates a very intense and tight rotation and in my eyes is a clear give away that a large tornado is most likely on the ground. The velocity imagery reminded much of the Greensburg, KS tornado radar imagery. Below the velocity from the Greensburg tornado and Yazoo City are shown.

I would expect this tornado to be rated at least an EF-3 in intensity, if not higher. I have seen plenty of radar from tornadic events and this is up there. To put this into perspective the velocity shear from this is higher than that of from the Moore, OK F-5 tornado in 1999. This, however, may be due to the fact that the radar in Mississippi was much further away than the Oklahoma City radar in the Moore tornado case as the radar may be sampling more of the mesocyclone circulation if the storm is further away. Nonetheless, a very scary looking signature that led the National Weather Service to issue the rare "Tornado Emergency". I believe this is the fourth ever issued in history (Moore, Greensburg, Small Random Event, Yazoo City.) Half those tornadoes were rated F-5 and I believe the random event was rated F-4. Greg Forbes on the Weather Channel, from what damage he saw, believes that a rating of EF-3 is expected but as we saw with Greensburg the rating may be much higher than initially expected. The radar signature, to me, does not seem like an EF-3 case, I believe it should be higher. The weather service will announce the rating, most likely, tomorrow.

The setup was amazing. Parameters were off the charts, minus the instability as said in the previous post. This taught me a very important lesson: Marginal instability in high shear and good dynamics still leads to a great tornado threat. It certainly is rare for such high low level shear to be matching up with the instability, but it happened today. The significant tornado parameter in Mississippi around the time of the Yazoo City tornado was reaching over 10, some of the highest values I have seen. All other parameters, as well, were off the charts including helicity (over 300), EHI (over 10), and the supercell parameter (over 20).

The next severe threat looks to be this coming Thursday, as a large, negatively tilted trough will approach the midwest putting Iowa in the perfect spot for significant severe weather. It appears the main problem will be instability. It is very difficult to get good moisture into Iowa this time of year so this is expected. Otherwise the wind shear looks perfect. 500 millibar winds are from the SW around 70 kts which will be favorable for supercells and surface winds are out of the SE meaning low level shear will be great. As we near Thursday the threat will become clearer. Do expect some tornado threat in the region around Thursday. Currently I work Thursday, but I may try to find a replacement especially if things continue to look good.

Images below:
Greensburg, KS EF-5 Radar Storm Relative Velocity
Yazoo City Tornado Radar Storm Relative Velocity
Significant Tornado Parameter 18z
Thursday @ 7pm 500 mb plot

Chase Review April 23rd, HIGH Risk tomorrow

2010-04-24T01:24:00.004-05:00

You can add another talley to the list of busts that I have been a part of. I am really starting to feel super unlucky when it comes to this storm chasing gig. Once again storm development held off during peak heating. I have now been a part of 11 chases and have yet to be a part of any significant severe weather. I have chased a few supercell storms, but all of them have been messy and weak. Frustration is really beginning to set in.

I left with some friends from Ames to Nebraska City, NE. There we waited for over three hours and watched cumulus clouds try to break the cap. It was very neat to watch this as vertical development was obvious but seemed to be halted at a fairly high height which is somewhat confusing considering the cap was around 700 mb, maybe that is how high actually was. A tower did eventually go up, right next to our location, but quickly fizzled out and by this time it was nearly 7:30 so we called it quits and headed home. Other storms did develop in SE Nebraska just before nightfall but none of them produced tornadoes, only some small hail. One stupid chaser reported on spotter network that a large wedge tornado was on the ground which was 100% false. I hope that person is removed from spotter net as that is totally unacceptable. How can you mistake a cloud feature for a quote on quote "quarter mile wide wedge tornado"?!

I felt we played the setup well and chose a perfect spot as the first storm did fire right next to us. We also called it quits at the right time and did not get burned on time or but a late tornado report. Frustrating bust, but well played. I pretty much called the plays on this chase and felt good about it.

As for tomorrow, SPC has issued the rare high risk for severe weather. The high risk is centered over northern Mississippi and Alabama. The tornado probability for this area is 30% hatched which is an unbelievably huge number, I have maybe seen this a couple of times if that. They are forecasting a severe weather outbreak with numerous tornadoes and a few long-lived and violent tornadoes.

What do I think? SPC is overhyping this, once again. I may be bitter about today, but it is obvious that this setup is not "ideal". If you are going to issue a high risk the setup must be ideal and make the forecaster 100% confident on at least 10 tornadoes and a few strong and damaging ones. Will this happen, most likely, but not for sure. There is one big thing that worries me and that is the instability over that region tomorrow. CAPE will max at 2000 and average around 1500. This is right at the borderline for favored conditions for tornadoes. Famous long lived tornadoes and outbreaks are associated with CAPE of more like 3000. The good thing about this CAPE, however, is that is in phase with the very strong shear. Storms will rotate tomorrow and with the added low level shear, the tornado threat is strong. But once again this 30% chance is ridiculously high, SPC should have stayed with the 15% hatched which in itself is very high. They seem to think with a very strong low level jet, no matter what the instability is, that an outbreak is guaranteed. They called for an outbreak for today, didnt happen. Time and time again they have screwed up. Maybe some credibility will be regained tomorrow, but with many high risk forecasts things tend to not verify well. Good luck SPC.

Images are:
SPC Tor Prob
Sig Tor 4pm
SPC Categorical
CAPE 4pm

Severe Weather in Nebraska, Review of April 6th chase

2010-04-13T17:58:00.002-05:00

A line of thunderstorms has developed from northern Colorado through western Nebraska into southwest South Dakota. A few storms that developed ahead of the line showed some organization but no tornadoes have been reported.
The tornado threat seems to have diminished for today, but a small spinup along the line cannot be ruled out. Mainly high winds and hail will be the main threat in the next six hours.
In the next few days the severe weather threat will diminish. The synoptic scale trough will propagate northeast and give parts of NW Iowa and Minnesota a very small chance of thunderstorms. If storms do initiate, they will be in a low CAPE environment as well as poor low level shear environment. The severe threat is minimal and SPC agrees as the day 2 outlook shows Iowa in the general thunderstorm threat (level below slight risk).
The next risk for severe weather in the midwest appears to not be until Thursday April 22nd where the next major weather system will roll in. Until strong ridging will be in place giving way to strong high pressure. A chance of some precip may roll in this Sunday as a weak short wave will move in but it will not have the dynamics favorable for severe weather.
Hopefully things pick up in late April. I have finished my review from the April 6th, 2010 chase in eastern Iowa. You can read that here:
April 6th, 2010 Chase Review

The following Image is North Platte's radar from today around 6:15 pm

Update: Friday April 6th, 2010

2010-04-09T13:24:00.004-05:00

Hello all,

The weather has quieted down across much of the midwest. Currently we under a large ridge of high pressure keeping our skies clearly and dragging in much warmer temperatures in the next few days. High temperatures in Iowa will begin to flirt with 80 degrees once again Saturday and Sunday.
Our next system looks to move into the western plains on Tuesday. It appears that this system will be redirected to the north to around North Dakota meaning Iowa will most likely stay clear of any severe weather threat. The main threat looks to be centered around western Nebraska into South Dakota and North Dakota. Since it is still April moisture will be very limited up there with forecasted dewpoint temperatures in the lower 50s. This should lower the severe threat quite a bit in a number of ways. The upper level pattern, however, looks to help keep a strong system in place giving way to surface winds out of the SE. This will increase directional shear tremendously meaning a tornado threat could be possible come Tuesday in eastern South Dakota. The deciding factor will be if enough moisture can move in to provide instability, model CAPE Tuesday evening is 0 as of now.
As for Iowa, the next severe threat does not appear to be clear yet. The upper level pattern becomes more NWsterly which usually is associated with high pressure, however little disturbances will ride along the main flow into Iowa meaning that lift will be present. I doubt that enough instability will be in place though to create a good severe threat.

Next Severe Threat:Monday April 12th in Nebraska and South Dakota, risk is very conditional upon moisture return from gulf.

Image is the GFS model forecast of dewpoint temperature Tuesday at 7pm.
Review of April 6th Chase coming soon!

Chase Potential 4/6/10

2010-04-06T00:06:00.003-05:00

Here are my current thoughts regarding a potential chase for tomorrow, April 7th, 2010.
Overall synoptic setup has not changed as much, warm front pushing further into Iowa shifting the primary tornado threat from NW MO into Eastern Iowa. The triple point will be around Des Moines by 21z making I-80 and points east and south to near Cedar Rapids and Ottumwa potential target areas. Initiation appears to be just east of the triple point around 21z near Knoxville to up near Marshalltown. Main concern is how far north will the warm front advance as this will be a strong deciding factor on whether we travel on highway 30 or interstate 80.
Unfortunately models indicated SSW surface winds unlike the nearly SE winds we saw today meaning our low level SRH has been lowered much more than yesterday, but values still exceed 150 for the 0-1km layer which is still favorable for tornadic storms. As we approach 3z a linear system will develop most likely along the Cedar Rapids to Iowa City to Washington line. I see supercell storms developing in a rectangle from Osceola to mt pleasant to cedar rapids to ames. Preliminary target, not to say this will happen as I will most likely be going on a class chase, would be Newton.

Reflection of Chase 4/5/10

2010-04-05T23:52:00.002-05:00

Overall I think our chase went very well minus the fact the cap did not break. We successfully coordinated up to five vehicles across northern Missouri to where the threat for tornadoes was the greatest during the day. We called it quits when we needed to, about 6:30pm. We did not get excited about elevated convection earlier in the day and kept our eyes peeled on Visible Satellite and ruc images.
RUC model skew-ts throughout the day hinted at the cap not breaking, but I am somewhat surprised by this, especially since the KTOP 0z sounding showed the CAP basically eroded. Convection did begin to break out later that evening but that was not until around 8pm after dark.
I'm overall disappointed in the cap not breaking because the shear at all levels was amazing and I almost guarantee any surface based convection would have yielded strong rotating thunderstorms. Nonetheless it was a good warm up chase and I feel very good about going out with Andy as a lead chase partner alone without grad student or professor help.

Heading back to Cedar Rapids

2009-06-20T14:26:00.004-05:00

Hello all,

Today I am in Ames preparing to work at the always delightful restaurant, Culvers. As many of you know I am not a big fan of waking up early to drive a fair distance to go somewhere especially if that place has my bed that I can sleep on. With that being said I plan on driving back to Cedar Rapids tonight after work which may mean that I will not be getting back till 1 am. Sounds dangerous? Nah, I just love driving to places late at night, I drove from minneapolis, mn to cedar rapids, ia beginning at midnight which put me back home at around 4:30am. I have also driven the mobile mesonet after driving for 7 hours during the day from topeka, ks to ames, ia starting at 9pm which puts us back in ames, ia around 2am. I am not really all to worried about driving home for two hours.
I am going back to Cedar Rapids to celebrate fathers day at my dad's house where the family gathering will take place. It has been a while since I actually have attended a family gathering so it will be nice to be present.
As for the weather tomorrow it actually looks like unsettled weather may roll into eastern Iowa. There is still a trough sitting over the west coast that is pumping disturbances into the plains. The bad news is that a ridge is beginning to build over the central part of the country which will redirect these disturbances further north, but fortuanetly for tomorrow it looks like eastern Iowa will be the target for this coming disturbance. A warm front will be drapped across the state which will be the focus for thunderstorms to develop.
I have a couple of worries for tomorrow:
1) bad upper level flow: 500mb winds are forecast to be between 35 and 45 knots, I really would like that number to be more like 50 knots for better overall shear for supercell structures
2) tonights convection: The atmosphere is very moist right now which with that warmfront we will be seeing heavy rains and thunderstorms tonight that may affect the instability tomorrow if cloud cover sticks around too long.
There is good news though! If storms develop and become organized the risk of tornadoes with these storms may be great. Low level helicity values are forecast to be between 150 and 250 which as stated by last post anything over 100 is good enough for tornadoes. These numbers are not huge but will increase the risk of tornadoes which has made SPC put "isolated tornadoes" in their day 2 outlook.
My plan is to watch the situation tomorrow at my dad's place and if anything gets fairly close to Cedar Rapids (basically within a 30 mile radius), I will go spot for the weather service. If initiation is late enough maybe my dad will come with assuming the fathers day get together is over.

The above pictures are:
Day 2 Outlook by SPC
MLCAPE for 7pm tomorrow (instability)
Sig Tor for 7pm tomorrow (tornado risk)
Effective SRH for 10pm tomorrow (low level wind shear)

BUST

2009-06-18T23:35:00.002-05:00

SPC does it again... bust! no tornadoes were reported in the 15% hatch which is absolutely horrible. Like June 6th the cap held and yielded nothing but partly cloudy skies. What a day for this to happen seeing as I saw parameters breaking numbers I have never seen before.
One parameter called the Significant Tornado Parameter, which is measure of the likelihood of tornadoes if storms were to enter that region , broke into the 10+ range, sig tor of just 1, yes 1, is good enough for tornadoes.
Another parameter called CAPE which is a measure instability broke into the 7000 range on an observed balloon launch which is NUTS! This was not a model forecast of this parameter, this was actually based on observed conditions. CAPE of over 1000 is good enough for good supercell storms. Also on that same sounding 0-1km Storm Relative Helicity, basically wind shear, was over 400, any numbers over 100 is good for tornadoes. The data from the balloon launch is shown above.
The cap held and as shown today no matter how great parameters are you need the storm to go off first, how frustrating. Tomorrow may be a potential chase, I may actually go to Cedar Rapids in the morning if the tor risk is high enough in eastern Iowa, I really do not want to go too far east though.

No storms= Me playing with my webpage

2009-06-11T23:35:00.000-05:00

So I'm bored again so I have been working on my website.. .again... I was working on the new weather challenge website because the old one was lame and now since I am managing that I made it look pretty and hopefully people will use it now because it makes it easier.. hopefully.. to forecast...
the weather challenge website is here
http://www.meteor.iastate.edu/~ralliss/wxchallenge/index.html

I also am now changing the layout and theme of my original website to look more like the wxchallenge site because it looks 20000000 times more professional...

Comments are welcome!

Ryan

SW Missouri getting rocked by extreme instability!

2009-06-10T19:06:00.003-05:00

Southwest Missouri is under some crazy instability today, the cap finally broke around 6pm which is leading to some large and dangerous thunderstorms. With this large instability leads to strong low level accelerations which even without significant low level shear allow for tornadoes to develop which is the case today. The radar image shows all the tornado warnings at around 7pm. None of these storms have a persistent rotation however brief spinups look to be possible. A parameter we use in severe weather forecasting is called CAPE which stands for convective available potential energy which is a measure of instability. Values of 1000 or more are sufficient for supercells, today as the contoured image shows we have between 4000 to 5000 units of energy in SW Missouri. I anticiapte these storms to last for quite some time with heavy lightning and strong winds.

As for chasing I think maybe the next threat close to home may be Saturday but looks to be slight at best for tornadoes. There is still a large trough in the SW US which once it decides to move east I anticipate a good chance of another round of consecutive chase days in tornado alley.

No tornado, but still a success

2009-06-08T13:25:00.002-05:00

All details of yesterdays chase and the June 6th Chase can be found here
http://www.meteor.iastate.edu/~ralliss/chases/2009/2009

Ill start working on that

Ryan

Chase Update, sounds like it is going to be a GO!

2009-06-06T00:09:00.003-05:00

After a rather active day of severe weather in Wyoming into Nebraska attention now turns to southeast Nebraska for the next punch of severe weather. Today Vortex 2 finally intercepted a tornado after a drought of horrible weather conditions. This storm was the perfect setup for Vortex 2: a discrete, slow moving supercell in flat terrain with no property in the tornadoes path. I happened to be watching radar at the time and captured the screen shot as seen above. If you were watching the Weather Channel you got to see this tornado through the entire life cycle live. This screen shot is at tornado time showing the classic supercell with the hook as well as the "Tornado Vortex Signature" as shown by the inverted green triangle. I also believe TWISTEX intercepted this storm yielding a hopefully successful day for them. I doubt any good probe data was recorded due to the low density road networks in nowhere southeast Wyoming.
As for tomorrow, things are looking good and exciting. We finally are getting a good setup for tornadoes that is making a four hour trip look to be worth it. After discussion with ISU's top chasers we have decided our intial target area will be between Lincoln, NE and Nebraska City, NE (based off of the 7pm model run, next one we will look at tomorrow morning). The current plan is to meet at Scott Lincoln's place, a gradute student in meteorology, to have a weather discussion and determine where our target will be. Then we will hit the road and hopefully get some good intercepts. I hope to finally use my gps software and phone internet on the field using my car, she has a fresh oil change so hopefully no break downs.
The setup tomorrow looks pretty good. The factor that we really have yet to see in these neck of the woods is decent wind shear to help get supercells, this looks to be finally here. Looking at forecast wind speed and direction with height shows beautiful directional and speed shear around Nebraska City which screams tornado winds. As for istability the models are putting a good bullseye around there with the models progressing higher due to larger moisture forecasts at the surface. Remembering from last post I wrote that moisture was needed, it looks like we may be getting enough now. Sig Tor numbers are bumping more than enough above the liked level (usually you want around 1, some areas in SE NE are forecast near 5.) I am very excited about tomorrow, hopefully I can provide an update tomorrow morning but if I do not assume that I have hit the road. I will be with Scott Lincoln which on spotter network his id will be slincoln which will show his location on a map.

Current map to view spotter locations:
http://www.spotternetwork.org/google.php
Again look for either slincoln or Alliss on the map, thats where we are at when updated tomorrow

Chasing tomorrow!

2009-06-05T11:45:00.002-05:00

Hey everyone,

Yet again it has been a while since my last post, sorry about that. The last post I mentioned chasing the following day which did not go down. We had a weather discussion in Agronomy hall with some meteorology professors and came to the conclusion the setup was not favorable for tornadic storms which ended up verifying very well so we ended up saving some gas money.
As for this weekend things look to be active. Today eastern Colorado and western Nebraska have a 10% tornado probability which is exciting and I am pretty sure VORTEX 2 is going after that. I'm not about to drive 8 hours to get there so I'm just going to have to settle for tomorrow. There is currently a slight risk of severe weather for much of the western half of Iowa for Saturday. After taken a look over at things the main concern will be lack of moisture with dew points barely breaking the 60 degree mark. Me being an optimist I looked for some higher values in the model runs and found that one model, the GFS, puts a bullseye of 65+ dew points in central Iowa which is thus leading to high instability forecast values. It is also eroding the very annoying cap which inhibits storms from going up. On some days it will be the greatest setup ever but if the cap holds sunny skies will persist all day; hopefully that does not happen tomorrow. The picture above is a forecast skew-t chart which graphs temperature, dewpoint, wind speed, wind direction, and parcel path with height. This forecast chart is for Ames and when I pulled this up I was very suprised to see it.
We need three things for tornadic storms
1)instability: skew-t chart for ames shows 3000+ CAPE which is more than what you need
2)Wind Shear: chart for ames shows 200 SRH which you need around 100 for tornadoes GOOD
3)Lift:warm front/stationary front will provide our lift tomorrow

If that skew-t even remotely verifys tomorrow we will see tornadoes in central Iowa, now the other models are not showing those high moisture numbers but seeing how crappy this season has been I am going to take the optimisitic road and get excited.

I will post tomorrow before I leave.

Thanks for reading!
Ryan

Some hope has arrived

2009-05-29T00:08:00.005-05:00

Hey everyone,

it has been a while since my last post but I'm sure most of you know why, the weather has been very very quiet. Severe weather experts are astonished by this month and it is very incredible how strong this pattern has been. This last month the pattern has been more like a summer pattern that keeps disturbances further north up into Canada. Also a strong area of low pressure that was flirting with tropical depression down in the gulf was sucking all our moisture away which thus led to one of the dullest severe May's in the history books.
Well seeing as I have posted maybe you got the hint that yes indeed I am thinking about chasing again, and you are correct if so. The storm prediction center has circled Iowa for a potential risk of severe weather beginning Sunday leading through Monday. After looking things over I believe the better tornado day will be Monday due to the better upper level flow. Potential targets right now include far north east Kansas, southeast Nebraska, northwest Missouri, and southeast Iowa. I just spent a good chunk of cash for chasing including GPS software and finder, a power inverter to plug things in that will charge through my car battery, and the most exciting: phone tethering that gives me fast internet anywhere as long as I have a verizon wireless signal on my phone, I plug my phone into my computer and it gives me internet. I don't want to get completely busted this season so I think I may go all out Monday. I do not have to work so that is great. The only thing I do need to do is get my car ready aka oil change.
I potentailly may go with TWISTEX some other time even though I am not scheduled because they realized how bad the weather has been so they are allowing three ISU students to come along, I will not be going with them monday because I have to work the following day.
Updates about Sunday and Monday soon.

Ryan

This sucks

2009-05-20T02:01:00.001-05:00

Well the weather is being lame so I've had a lotta time to work on random stuff including my Meteorology webpage so if you have time go ahead and check it out!

Ryan Alliss' Meteorology Home Page

Thanks!

Ryan

The Weather isn't cooperating

2009-05-18T18:00:00.004-05:00

Some people may love 80 degree weather with clear skies, dry conditions, and a stiff southerly wind but I am beginning to hate it. Currently a large ridge is dominating much of the western part of the country yielding extremely warm and dry conditions. This ridge will persist through tomorrow until our next disturbance moves in from the north. A trough will dig into the Dakotas Wednesday which will give areas of the northern plains a chance for showers and thunderstorms. Will these storms be severe? Well right now both the Storm Prediction Center and myself say no. This ridge has dried out our atmosphere which is going to make it very difficult for a strong moisture return up into the northern plains. Surface dewpoints range from the 40s into the low 50s. With temperatures forecast to be up in the mid to upper 80s we need dewpoints near 70 otherwise our storms will be elevated with very high cloud bases, all not good for tornado development. Wind shear also looks poor. This next system looks not to be a great producer of severe weather.
Well what about after that?
The models show hardly anything.... A short wave will give a chance for showers and thunderstorms in Nebraska and Iowa Sunday but again dry conditions should keep these storms below severe criteria. The 16 day GFS forecast shows an omega block setting up the northwest which will drive all disturbances into canada keeping most of the United States dry and warm. High pressure looks to dominant.
For May there is 189 preliminary reports of tornadoes in the US which if high pressure holds the tornado amount below 200 this will be the lowest amount of tornadoes since 06 with a current 3 year average of around 284 reports for May. Also prelim reports tend to be higher than actual, so this month is looking very poor for tornado amounts.
I am currently beginning to work on my thesis for my senior research project which is going to be severe weather related and hopefully be related to a potential relation between merging storms and tornadogenesis.
I have upgraded my phone to a plan that allows me to get internet on my laptop when my phone is connected it so after TWISTEX I will be able to chase seeing as I will have both radar and gps software which are the two essential things for chasing.
The picture above shows the small disturbance in Montana that will produce some rain and potentially a thunderstorm in the Dakotas. You can also see the large ridge to the east and unfortunaetly you can see another ridge off in the Pacific that will take over again.
What we need is a large trough that digs deep into the country that produces a chance of storms closer to the moisture source down by the gulf of Mexico.

Well optimism is all I have left now...

Ryan

Back in Ames, no Luck

2009-05-16T03:00:00.005-05:00

Well after a very long day of driving across Missouri into Kansas we were unsuccessful for an intercept. One tornado was reported in Texas, way outside of our area for intercept, just a bad day for tornadoes everything turned into a massive line which really killed the tornado threat, we did watch one storm in Kansas try to organize which showed a little lowering which may have been a wall cloud trying to develop however it weakened very quickly. We let the line run into us which resulted in some very high winds probably gusting over 60 mph along with some pea size hail. Afterwards we headed north to Topeka where we ate at a Japanese Steak House then Chris and I decided we would dare the trip back to Ames, a good 4 and half hour drive starting at 9 pm. So we just got back around 2:30 am.. I love driving late at night apparently. It was great to be a part of the crew, very exciting to drive one of the four vehicles in the armada, it was quite the experience. Looks to be a quiet pattern coming up, next potential chase day may not be until Wednesday or Thursday of next week, hopefully we can get something in here. Well I put in a good 12 hours of driving today so I'm going to bed.. I'll be bored out of my mind the next coming days so feel free to call me.

Ryan

Current Location: Macon, Mo

2009-05-14T23:44:00.003-05:00

Alright after a very long day of driving which included a few changes on our destination. The farthest south we went was to Kansas City where we ate at a Denny's next to the Kansas City Royals and Chiefs stadiums. A picture of the mesonet in the stadium parking lot is shown below. We then headed back north to due to a change of destination which was to be in central Missouri. After a few more hours on the road we arrived in Macon where I finally got to meet the crew. Off their last chase success in Kirksvile everyone was very exited. We spent the entire day working on preparing the other mesonet cars including the one I will be driving for action. This included mounting a large antenna to the back bumper, upgrading the radio, checking software functionallity, and looking over the accuracy of the mesonet sensors. A couple pictures below show the mesonet car. Reed Timmer also stopped so I got to meet his crew and the infamous tvn new vehicle which is like a miny tiv. The discovery channel is filming full force, I don't think a cameraman will be in my car but they definetely are getting a lot of footage, I'm sure they will show the Reed and Samaras meeting on one of the episodes.
Tomorrow is going to be the full crew's first chase day. We are currently thinking north central Missouri is the place to be, much like the Kirksville tornado day. We will be calibrating our sensors tomorrow around 10 am, having a weather discusion, and then probably hit the road between 11 and noon. I'll be taking as many pics as I can, my phone right now is my main source but I do have my digitial camera with me so I will do my best to get some decent shots.
As for driving the mesonet, it should be interesting, these guys don't fool around so I may have to do some fancy driving especially if things ramp up, thank God I got some chasing driving experience! People give us the funniest looks when we drive by and when we get gas randos will come up and ask me what it is or "are you a storm chaser?" which gets old pretty fast.
Tomorrow is going to be exciting, updates as soon as possible.

Ryan

In Cameron, MO

2009-05-14T09:30:00.002-05:00

Hello everyone,

I currently am in Cameron, MO waiting to me up with the rest of the crew on TWISTEX. Chris and I are waiting in a Super 8 parking lot looking over stuff and waiting. The rest of the crew is in Hannibal, MO because they intercepted the supercell producing a tornado up by Kirksville. My friends were on that storm as well, unfortunately it was rain wrapped so did not see, they did a lot of interesting things but did not see the tornado itself. I thought I saw it on webcam on justin.tv but I'm not really sure. This cell tracked from near mid Missouri all the way across to the Mississippi where it eventually died out. This storm was dropping tornadoes basically the entire time showing constant rotation on radar.
I am actually driving the mobile mesonet for the TWISTEX which was a suprise to me, but definetly give me something to do. I will update later about tomorrow and how my first meeting with the crew went.

Ryan

My friends are on their way to Kirksville, MO

2009-05-13T11:28:00.004-05:00

My storm chasing friends decided that Kirksville, MO is going to be their target today. They are already on their way which is good because initiation of these storms looks to be potentially early afternoon in central Missouri, a little bit later up by Kirksville. Central Missouri is looking to be under the gun right now, skies are already clearing which will break the cap early. Wind shear is looking prime for points northeast of Springfield up to around Chicago. The biggest threat for tornadoes as SPC has well highlighted is shown here. This image is the tornado probabilities for today, and look what we got, yes that is a hatched outlook for tornadoes.. very exciting. As the description says within the hatched area there is a 10% or greater probability of an EF-2 to EF-5 tornado striking within 25 miles of any point, meaning that destructive long-lived tornadoes are possible there. Stockton, MO is out of the hatched area however you are still in prime instability which with even a little wind shear, whcih you have, can give a tornado threat as the 5% prob is showing. The threat in Iowa I believe has completely dominished in this last model run, the reason being cloud cover. Cloud cover is going to keep our cap strong ceasing any large storm development. The showers and storms this morning were remnents from last evenings storms in Nebraska. As I said in my last entry I am in Ames and will be watching radar for them. This has to got to be the most exciting chase for the group this season, really unfortuante that I am unable to join them. Hopefully tonight I will be leaving for Kansas for TWISTEX. That update will be posted immediately as soon as I get the information.

You can also watch live streams of stormchasers including TWISTEX, TIV, and Reed Timmer at the following site:

http://www.justin.tv/stormchasers

Ryan

I've been told Wednesday Night

2009-05-12T18:06:00.004-05:00

I got an email yesterday from a grad student here at Iowa State named Chris about when I will be heading out. He said that it is very likely that we will be leaving for somewhere in Kansas tomorrow night to meet up with Tim. I'm a little frustrated because tomorrow there is going to be a big risk of severe weather throughout much of the central part of the country including some prime chase spots like Oklahoma. They are having equipment problems so we will not be deploying tomorrow. It will be a meet up day and then go from there. I'm a little confused because chasing Thursday looks horrible, not till Friday will things look up for us. The most frustrating thing is that my friends will be going to eastern Iowa tomorrow to chase and I will be stuck in Ames waiting for orders on what time to depart. I told my friends I would provide radar analysis for them seeing as they will be on the road and will not have the best program for radar.

As for tommorrow things are looking very interesting. After looking over everything I feel there are two primary areas of interest for tornadoic development: Southeast Iowa into Western Illinois and later on into central Oklahoma. Above my outlook is drawn for tomorrow. I have a moderate risk in the two areas I mentioned as well as a slight risk extending from southern Wisconsin down to Texas. The main problem in much of the slight risk area is will the cap break? A cap is a warm pocket of air aloft impedeing storms from developing. The moderate risk areas have the best chance for the cap to break as well as excellent wind shear. Up in Illinois this system should turn into a line along the cold front but a few Supercells should develop ahead of the front which may cause tornadoes. The Oklahoma threat will be in the evening which talk of vortex 2 jumping on this has been heard on the Weather channel. The cap will be a big problem down here and we will have to see with the next model run whether or not enough cold temps aloft move in from the west with the main disturbance causing all this unsettled weather. If the cap does break there is more than enough energy to produce large storms and along with plenty of good winds will provide yet again another good chance of strong tornadoes. Springfield, MO sounding shows plenty of instability but winds more representative of a line event rather than a tornado threat, however an isolated tornado cannot be ruled out throughout the entire risk area.

It will pain me to be in Ames tomorrow that is for sure. I will keep my eyes glued to radar and "virtual chase". I will be probably waking up a little bit earlier tomorrow to update the situation as the new model run comes in at 9 am.

Ryan

Tuesday Update

2009-05-11T14:10:00.000-05:00

I have yet to hear from anyone which I anticipate is because the Storm Prediction Center lowered the risk for Tuesday just for Nebraska and North Dakota. However the latest model run is showing a very interesting setup for eastern Oklahoma tomorrow. Severe parameters are going through the roof with this run. The main problem will be breaking the cap to free all the energy that will be out there. With this latest model run this is how I believe the risk should be edited for tomorrow as the above picture shows. As you can see I put a moderate risk for severe weather in eastern Oklahoma with a slight risk stretching up through Kansas into North Dakota. I'll watch SPC to see how close I get to their next update.
The storms, if they fire, in eastern Oklahoma will most likely be supercellular with a risk of very large hail, high winds, and intense tornadoes. The following picture shows a model product called Significant Tornado Parameter. Higher values have been shown to be associated a more likely chance of tornado development. As you can see high values appear in eastern and central Oklahoma. These values are really high, numbers that were not appearing on previous model runs.
I'm really hoping that TWISTEX jumps on this because this looks to be really good, however it would be wise to make sure the next model run keeps this in here. Never trust one model run.
Any changes in my current plan for tomorrow will be updated immediately.

Lookin like Tuesday

2009-05-10T23:22:00.001-05:00

Hello everyone,

Well I have yet to go anywhere other than Ames. I spent today cleaning up and preparing for new roommates here at my apartment.

According to twistex.org our team is suppose to be prepared for a multiple events starting this Tuesday. This means that my first likely day to head out will be this Tuesday. Where will I be headed? Well according to the Storm Prediction Center a slight risk for severe weather is forecast for parts of Nebraska and Kansas as the picture shows. On Wednesday the unsettled weather shifts to the east yielding a risk of severe weather for parts of Illinois and unfortuanetly for Missouri. As some of you know Missiouri roads make chasing very difficult, which I got to experience first hand as a driver this last week when I made my way near Bethany, MO. The Day 4 risk is as shown. I anticipate that I will be sent out to Nebraska Tuesday and then spend the night in a hotel that night and then move further east towards Illinois or Missouri. I don't know exactly what Tim Samaras, the TWISTEX lead investigator, thinks about Missouri but I'm sure he is not much of a fan either.

The models show unsettled weather through Friday for parts of tornado alley which may lead to four straight days out on the field which would be awesome. High pressure will then move in Saturday taking away any thunderstorm chances throughout all of tornado alley.

I expect to hear from Chris Karstens, a graduate student here at Iowa State, to contact me about heading out Tuesday tommorrow. I also found my camera so I will bring that with along with my laptop assuming that I'm allowed too.

I will post tommorrow as soon as hear from him regarding the status for Tuesday.

Ryan

I am now on call for TWISTEX... Vortex 2 Begins as well

2009-05-09T23:13:00.000-05:00

Hello all,
I am now back in Ames after spending two days back in my home town of Cedar Rapids. It was nice to catch up with family and friends. I came back tonight because tomorrow is the day I was told that I could be potentially be sent out for TWISTEX. TWISTEX is a tornado research field experiment that involves taking cars with instrumentation on them and bringing them near a tornado and the parent thunderstorm to get valuable data for research purposes that hopefully lead to a better understanding of the trigger for tornado formation. You can learn more about TWISTEX here:
TWISTEX website

Right now I have heard nothing from them so I am assuming I will not be leaving tomorrow. The risk for severe weather is far south in Arkansas and points east. There looks to be some good unstable air that will move into arkansas as the day wears on, however wind shear looks to be little. I don't anticipate a very big tornado day tomorrow. Above is an image of Sig Tornado for tommorrow. Nothing amazing showing up on there. High values showing up in Texas however the cap will most likely hold convection down in that area.

Unfortuanetly the near future looks bad for chasing as well. Models are showing a strong area of high pressure dominating much of tornado alley. Looks to be a non-severe threat around here up until Wednesday. SPC has a day 5 convective outlook out. This would be Wednesday so I may not be going anywhere until then. Of course the days its starts I get lovely high pressure.

Thanks for reading and I'll make sure I keep this updated.

Ryan