Severe Weather Event Discussion

[Guest ChaserUK]

Hiya Matey - yes I think we are about to get rid of that aweful high and start bringing in a few disturbances. In fact looking at last year, there were 17 tornadoes the 1st week of May, then all hell broke lose with another 470 the following weeks so we could be in for a real ride!

[stevestorms]

Hiya Matey - yes I think we are about to get rid of that aweful high and start bringing in a few disturbances.  In fact looking at last year, there were 17 tornadoes the 1st week of May, then all hell broke lose with another 470 the following weeks so we could be in for a real ride!

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Got a email from Dave Edwolt he seems to think things are picking up from this weekend and some of the models now show good chance of severe storms :-) leaving at 3am hoooooooorah! see yer over there Matt

[Paul Sherman]

Yes It will be great to meet up out there, really looking forward to this now, see you on the Plains Steve!!!

Paul Sherman

[stevestorms]

Ok Paul, hope so we managed to find Matt last year with a few phone calls so hopefully we will be in the same area and hook up for a Burger, we will have a people carrier type vehicle with lots of arials on it not sure of the colour yet but will let yer know, have a good flight.

[Guest ChaserUK]

Cheers Everyone - and you were down a little lane in the middle of nowhere eh Steve? I just remember seeing your car headlights on top of a hill with towers all around! Anyway, here is the latest from David Gold, pay attention to the last few lines!!!

Severe Weather Outlook

Wednesday May 4, 2005

Severe weather pattern to emerge over Tornado Alley once again

After an extended lull, the large-scale atmospheric currents are once again evolving towards a pattern favorable for persistent severe thunderstorm activity over an increasingly large section of the central U.S., beginning Friday.

A progressive series of upper-level waves is lining up across the northern and eastern Pacific, poised to move into the western U.S. over the next 5-10 days. This discussion will focus on the two easternmost systems expected to impact the weather over the continental U.S. during the next week or so. The westernmost system is a rather intense circular vortex south of the western Aleutians. The eastern system is comprised of two primary circulation centers oriented meridionally roughly along 135W. These two vorticies are in the process of merging, resulting in a fairly high-amplitude upper-level trough over the eastern Pacific. The southerly deep-layer flow along this trough's eastern periphery is - in turn - amplifying the downstream ridge along the U.S. west coast. As this trough-ridge system progresses inland over the next couple of days, the downstream amplification will spread eastward and will result in the growth of a large trough over the eastern U.S. This amplification will have significant consequences for the severity and location of thunderstorms by week's end. Although the entire wave train is moving along from west to east, the strengthening central and eastern U.S. trough - again, caused by the intensification of the systems over the Pacific - will result in surface cyclogenesis over the southeastern U.S. Thursday night and Friday and will also retard the breakdown of the polar low-level anticyclone currently parked over the eastern half of the U.S. This will result in the maintenance of continental polar air over most of the Gulf of Mexico and will retard the northward return of true tropical moisture until the aforementioned eastern trough and attendant surface ridging to its west move eastward into the Atlantic. This will not likely happen until early next week (to be discussed below). However, water temperatures over the Gulf of Mexico are in mid to upper 70's F and the overlying boundary layer has nearly attained equilibrium characteristics, comprising sea surface temperatures in the 74-76F range and dewpoints in the 68-70 range. This is the moisture source that will be available for the first Pacific trough as it moves into the western and central U.S. this weekend.

There are, of course, uncertainties regarding the evolution of the eastern Pacific trough and confidence in details won't be high until this system enters the U.S. observational network. However, most numerical weather prediction models agree on its general evolution: the trough is predicted to cross the U.S. west coast Thursday evening and move bodily inland into the Great Basin by Friday evening, overspreading the western and central U.S. plains with southwesterly flow aloft. Then most models rapidly eject this trough east to northeastward by Saturday evening in response to the approach of the first Pacific trough mentioned above. This is where the predicted evolution becomes more uncertain: how deep will the first trough be, and will its circulation be compact or elongated northeast-southwest? The latter scenario could result in a powerful southern wave approaching the southern Plains Saturday - an event that would result in a significant outbreak of severe thunderstorms along the Texas/Oklahoma dry line. A more compact wave with a northeasterly trajectory would likely keep the southern plains capped Friday/Saturday, confining the most significant convective activity to the central Plains. I have done a careful inter-model comparison and my thoughts are that there will be a substantial southern trough and attendant active dry line. Thunderstorm activity should be fairly limited Thursday/Friday as shortwave ridging builds over the Plains in advance of the first big wave, especially considering the fact that low-level moisture will be of modified continental polar origin. I do expect a few supercells Thursday and/or Friday over portions of the high plains. Here is where I will not speculate about the locations with the best chance for chaseable storms: this is going to be revealed in our forum so as not to tip our hand. I will say this, though. This first trough will likely result in pretty big severe weather event Saturday as it approaches the Plains and as increasingly rich moisture - topped by a pristine elevated mixed layer - flows northward ahead of the high plains dry line. Then by Sunday the best activity will probably be confined to Texas at the northern extent of the rich tropical air mass where it intercepts the trailing portion of the first departing upper-level trough. It appears that this first upper-level trough will "set the table" for the second monster wave, which should impact the central and southern Plains by Tuesday-Thursday of next week, during which time a classic tornado outbreak will be possible. Stay tuned for additional details. I'll have time to resume this discussion later this afternoon after I run some errands.

David Gold

[Guest ChaserUK]

BTW local Jersey Evening Post are doing another pre-chase story on us. They will do another on our return with a bag load of tornado pics!

[stevestorms]

BTW local Jersey Evening Post are doing another pre-chase story on us.  They will do another on our return with a bag load of tornado pics!

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WOOOO Yes indeedy looks like a good time to me fingers crossed Matt hope we can get the Baron up and running tomorrow night, good flight matey.

[Guest ChaserUK]

yes you too man - when do you get there?

[stevestorms]

yes you too man - when do you get there?

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James and I leaving at 3am from Norfolk picking Pete up in Essex around 04:30 get to Gatwick around 6:30 flight at 10:25 arrive FWT at 2:20pm local time driving to Norman Oklahoma arriving approx 6 to 7 pm phoning Dave and arranging a meet that night before we even think about sleep

Only 3hrs 27mins to go!!!!! not that im counting, see you guys across the pond this is my last post from the UK ALL THE BEST.

[Nabraxas]

Sounds like you're excited Steve.

I wish you all the best of luck with the storms, can't wait to see some of your photos/videos and most of all, stay safe.

Good luck.

[Guest ChaserUK]

Morning everyone. With Steve on his way now he shoudl be reporting back before too long. Below is an update on Sunday's potential and it looks like shaping up for a severe weather outbreak for sure. Initial thoughts now are moving North to Central KS - best to head for the triple point.

[Guest ChaserUK]

further update from SPC detailing are of interest - could be a large outbreak indeed.

[Guest ChaserUK]

Looking very promising. This is for 00z 7/5 to 00z on 8/5 -

...SRN AND CNTRL PLAINS...

A STRONG LOW-LEVEL JET WILL RAPIDLY RETURN LOW-LEVEL MOISTURE NWD

ACROSS THE GREAT PLAINS FRIDAY AND FRIDAY NIGHT. THIS WILL ALLOW FOR

MODERATE DESTABILIZATION ON SATURDAY FROM WEST TX AND OK EXTENDING

NWD ACROSS KS INTO ERN NEB. AS A WELL-DEVELOPED UPPER-LEVEL TROUGH

MOVES INTO THE PLAINS SATURDAY...STRONG ASCENT AND INCREASED

VERTICAL SHEAR ALONG THE INSTABILITY WILL PROMOTE SCATTERED SEVERE

THUNDERSTORM DEVELOPMENT.

THE MOST WIDESPREAD SEVERE ACTIVITY SHOULD BE CONCENTRATED JUST

AHEAD OF SHORTWAVES MOVING ACROSS THE REGION EMBEDDED IN THE UPPER

TROUGH. NAM AND GFS SHOW A DISTURBANCE MOVING ACROSS OK AND KS BY

EARLY EVENING WITH FORECAST SOUNDINGS SHOWING 0-6 KM SHEAR VALUES OF

35 TO 45 KT. THIS SHOULD BE MORE THAN SUFFICIENT FOR SUPERCELLS. AN

UPGRADE TO MODERATE RISK MAY BECOME NECESSARY IN LATER OUTLOOKS.

...NRN PLAINS...

AN UPPER-LOW WILL MOVE EWD INTO THE NRN PLAINS BY SATURDAY AS A SFC

LOW LIKELY MOVING ACROSS ND DURING THE DAY. WIDESPREAD CONVECTION

SHOULD BE ONGOING NORTH OF THE SFC LOW IN RESPONSE TO STRONG FORCING

WITH THE UPPER-LOW. AS LOW-LEVEL MOISTURE WRAPS AROUND THE SFC

LOW...INSTABILITY WILL DEVELOP BY MIDDAY PROMOTING A LARGE HAIL

THREAT WITH THE STRONGER CELLS. DUE TO THE MODERATE DEEP LAYER SHEAR

FORECAST BY THE NAM/GFS...CELLS HAVING ACCESS TO THE BETTER

LOW-LEVEL MOISTURE ACROSS SERN SD SHOULD HAVE A SUPERCELL POTENTIAL.

THE SEVERE WEATHER THREAT WILL BE DEPENDENT ON HOW MUCH MOISTURE CAN

RETURN TO THE REGION AND THE AMOUNT OF DESTABILIZATION THAT CAN TAKE

PLACE.

[Guest Mr_S]

How excited you must be now chaser!!!

Im still jealous of everyone going though! Good luck and stay safe to all going

Wonder if i can get 2 do Storm chasing in Australia....

[Somerset Squall]

How excited you must be now chaser!!!

Im still jealous of everyone going though!  Good luck and stay safe to all going

Wonder if i can get 2 do Storm chasing in Australia....

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I'm really jelous too, happy chasing!

[BrickFielder]

Good Luck.

Friday 6th

SPC has a slight risk out right now for parts of western Kansas and for a majority of Nebraska during Friday.

Low level shear will be favorable for tornadoes in parts of western KS and NE.

Indicators are that the Oberlin/Colby/Goodland area, depending on the develpment of the dryline could be a good place to start due to the high instability , but the best helicity is forecast in Nebraska.

Satuday 7th

Three options really Texas ,South Dakota or Kansas.

The latest model have a nice dry line from central Nebraska into the western panhandle of Texas. Forecast temperatures of at least 80F are located ahead of this boundary. Surface winds from the south, possibly a slight backing of the winds ahead of the dry line.The upper-air winds at 250mb are forecast to be SW and even SSW along the dryline. The best chance for rotating storms would probably be closer to Texas and the east texas panhandle.

The strong upper level system up in ND/SD/MN sure looks tempting as well, but the upper level winds are sufficent but not good and the dew points could be over estimated here.

Or as the SPC favours, In kansas Td's won't need to be too incredible to get some High Plains tornadoes out in Western Oklahoma and Kasas.

Tuesday 10th

a very potent system looks to be developing, and looks like it could produce some severe weather.

A deep upper level system at 998mb centered along the KS/CO border,with upper level winds in western Kansas and south into the northern Texas Panhandle being enough to sustain severe thunderstorm/supercell development. A theta-E tongue will stretch into Central Kansas.

[kold weather]

Hi Brickfeilder,on the 7th I decided to pick Kansas for my Virtual chase start point,then if I need to move about I should have enough time to do so,with several hundred cape and providing the DP's get high enough some good storms may spark off,but still to early to be sure of that,although i was also tempted by Texas as well though I must admit.

The system on the 10th is a very intresting one as you say,something worth keeping a eye on esp with that plume that you mention,worth watching definatly,I'll be paying close attention to the soundings on the day,actually might not be a bad idea to look at forecast soundings for the 10th so you guys gonig out there can get abit off foward notice as to what states are at most risk.

By the way,have a great flight over there guys and also stay safe,but most off all have a great time!

Edited May 5, 2005 by kold weather

[Guest ChaserUK]

Thanks for all the kind words chaps. We will try our best to bring back the very best reports and pictures that we can. We also hope to help out local NWS offices by reporting what we see. Not sure how much I will be on line between now and when I arrive. Peter and myself will be meeting Paul Sherman and Paul (Net-Weather site owner) tomorrow evening - will try and post some photos of that for you!

[Paul Sherman]

Much the same as Matt, have been busy packing the kit tonight but will be online up until 6pm tomorrow. Really is soooo close now.

Paul Sherman

[Guest ChaserUK]

I know - just HOW excited are you? As much as us I guess. Am working on a plan B for T-shirts at the moment - should look pretty kewl - if I can get them printed in time that is!

Also, had an email from Dave Edwolt, a Storm Chaser from OK, we chased with him last year and he's been doing this for 22 years. He told me ''.....I am more and more confident you guys are coming at a very good time...."

What can you say about that!!!!!!

[Gorky]

Saturday is looking very promising for some severe weather. Any chance you'll make it to the US in time to chase these storms or have you got things to do on the Saturday you arrive?

[Paul Sherman]

Hi Mate, No Saturday is looking all systems go, we will clear Dallas Fort Worth with Chase Vehicle and be in the middle of things in the late afternoon and DAY 1 COULD BE EXPLOSIVE Getting Cameras and Video Recorders charged at the mo ready.

Regards

Paul Sherman

[Guest ChaserUK]

LOL me too! In fact the following days are looking just as good if not better! Also, this is a very slow moving system which means two things 1 - storms will move slowly so nice to keep up with and 2 - the same areas will be hit again and again - not much driving involved hopefully! They are talking about discreet super cells in TX which makes for fantastic photo ops and likelyhood of tornadoes with inflows having no interuptions!

1 day to go, 1 day to go - see you and Paul tonight

[Guest ChaserUK]

plus I am seeing a decent return of moisture this morning up through TX which is very good news. Can also see a great dryline setting up already - this is looking promising.

[Stu]

plus I am seeing a decent return of moisture this morning up through TX which is very good news.  Can also see a great dryline setting up already - this is looking promising.

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Matt & Paul - bookmark this link

Storm forecast 7 days out