The countdown to Storm Chase USA 2008

[Paul Sherman]

Yep

There is a lot of talk of a Major Storm System from the 1-3rd May and over the Greensburg Anniversary Weekend <_<

Wonder Wether President Bush will cancel his trip to visit the area that is planned!

Paul S

[Paul Sherman]

Looks like we have a Growing support for a Severe Episode on Thursday 1st May - Let the Fun begin

DAY 4-8 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0412 AM CDT THU APR 24 2008

VALID 271200Z - 021200Z

...DISCUSSION...

GFS...ECMWF AND MOST MREF MEMBERS ARE SIMILAR IN EVOLUTION OF UPPER

PATTERN THROUGH MONDAY (DAY 5). SHORTWAVE TROUGH WILL AMPLIFY SWD

INTO THE SRN PLAINS AND LOWER MS VALLEY SUNDAY (DAY 4) BEFORE

EJECTING EWD THROUGH THE SERN U.S. MONDAY. SOME DIFFERENCES DO EXIST

WITH THE GFS AND MOST MREF MEMBERS BEING FASTER THROUGH THIS PERIOD.

BEYOND DAY 6 MODELS BEGIN TO DIVERGE MORE SIGNIFICANTLY.

...DAY 4...

SURFACE WAVE IS FORECAST TO DEVELOP ALONG THE FRONT AND LIFT NEWD

THROUGH THE TN VALLEY AS THE FRONT MOVES THROUGH THE LOWER MS VALLEY

AND SERN STATES. STRONGER VERTICAL SHEAR WILL LIKELY REMAIN POST

FRONTAL. HOWEVER...WITH ITS FASTER SOLUTION THE GFS DEVELOPS A

STRONGER PRE-FRONTAL LOW LEVEL JET AND DEEP FLOW OVER THE WARM

SECTOR. THE STRONGER KINEMATIC ENVIRONMENT SUPPORTED BY THE GFS

WOULD INDICATE A GREATER SEVERE THREAT AS STORMS DEVELOP ALONG THE

FRONT FROM PARTS OF THE LOWER MS VALLEY INTO THE SERN STATES. GIVEN

LINGERING UNCERTAINTIES AND MODEL DIFFERENCES REGARDING THE DETAILS

AND STRENGTH OF THE SYSTEM...WILL HOLD OFF ON A RISK AREA FOR NOW.

HOWEVER WILL MENTION THAT PARTS OF THIS AREA MAY NEED TO BE INCLUDED

IN A SEVERE RISK AREA IN LATER OUTLOOKS.

...DAY 5...

STRONGER VERTICAL SHEAR IS EXPECTED TO REMAIN IN POST FRONTAL AREA.

HOWEVER...MODELS SUGGEST DEEP LAYER FLOW WILL BECOME SUFFICIENT FOR

A THREAT OF MAINLY DAMAGING WIND AS STORMS INTENSIFY ALONG THE FRONT

DURING THE AFTERNOON...MAINLY OVER PARTS OF THE CAROLINAS INTO THE

MID ATLANTIC.

...DAY 6-8...

SEVERE POTENTIAL WILL BE LOW DAY 6 WITH ONSET OF OFFSHORE FLOW OVER

THE GULF. BEYOND DAY 6 MODELS BEGIN TO DIVERGE SIGNIFICANTLY. THE

ECMWF SUGGEST AN INCREASING THREAT FOR SEVERE STORMS OVER A PORTION

OF THE SRN PLAINS AND LOWER MS VALLEY BY DAY 8.

[kold weather]

ECM is looking better and better right now, the GFS is also showing a low pressure complex diving down over the plains after the 1st so thats another good sign, the GFS is a lot better then its runs from a few days ago. Do like the look of the upper lows on the ECM.

So looks like a slow start but that as I said before thats probably not a bad thing gives you a chance to adjust doesn't it!

[Gorky]

Looks like I could be Flying into a bit of severe weather on Saturday evening looking at the SPC page's outlook. I'm sure I'm going to be completely knackered after setting off at 4:00am UK time and chasing may be out of the question, but it will sure whet my appetite for the weeks to come :lol:

[Nick F]

12z GFS still seems less progressive than ECM in introducing the long-wave trough from the Pacific coast next week, and is more reluctant to break down the upper ridge over the Plains - and doesn't really break out any convection until Friday week over the Nern/central Plains, though after that it does suggest a more unsettled zonal pattern setting in with a good potential for t-storms over much of the the mid-west Plains.

Looking forward to the 12z ECM when it's released around 8.15pm, hope it carries on the 00z theme of a deep trough crossing the Rockies by Weds, with a good storm potential starting on Thursday. Bearing in mind ECM has handled the N American patterns much better than GFS of recent, and has been the prefered model for the US. Here's the prelim medium range discussion from HPC earlier today:

BEST AGREED UPON FEATURE USED FOR A TELECONNECTION TO AID IN THIS

IS THE STRONG NWRN ATLC RIDGING/CLOSED HIGH AND POSITIVE HT

ANOMALY IN THE LOWER DAVIS STRAIT OR JUST SOUTH OF CAPE FAREWELL

GREENLAND. THIS TELECONNECTS TO CONTINUED TROFFINESS OVER NERN

CONUS/WRN ALEUTIANS AND A TROF DOWN THE WEST COAST WITH HIGH

PLAINS RIDGING. THIS IS SEEN IN NEARLY ALL MODEL SOLUTIONS THRU

DAY 5. CURRENT MODEL MEANS INDICATE A PROGRESSIVE PAC FLOW PATTERN

AND THE WRN TROF SHOULD PROGRESS INLAND BEYOND DAY 5. THE ERN

TROF/CLOSED LOW IS BLOCKED AND FORCED TO ROTATE N AND NEWD INTO

SERN CANADA/NRN NEW ENG. BEST DEPICTION OF THIS WOULD BE BY USING

AN ENSEMBLE MEAN WITH A PREFERENCE TOWARDS THE LATEST 00Z ECMWF

ENS MEAN.

USING THIS MEAN ELIMINATES THE EXTREME OP MODEL SOLUTIONS OF THE

ECMWF OVER THE NERN PAC AND GFS EXTREME OF KEEPING A DEEP

CLOSED/CUTOFF LOW OVER NERN AND EVEN MID ATLC COASTAL CONUS. THE

ENS MEANS KEEP THESE FEATURES IN PLACE BUT VASTLY DOWNPLAY THEM.

HUGE ENS SPREAD INDICATES NO CONFIDENCE IN THESE FEATURES.

UPDATED HPC MORNING PRELIMS...DAYS 3 AND 4 SUN/MON A 50/50 BLEND

OF 00Z GFS AND ECMWF. DAYS 5-7 TUES-THURS 00Z ECMWF ENS MEAN.

ROSENSTEIN

[Nick F]

Thankfully, ECM continues with encouraging theme of falling heights over the mid-west by Thursday on arrival of the upper trough from the Pacific coast. The trough looks less amplified than the 00z, but nonetheless should increase the severe threat during Thursday and Friday:

[Paul Sherman]

I hope to God the guys are ready for this !!

DAY 4-8 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0354 AM CDT FRI APR 25 2008

VALID 281200Z - 031200Z

...DISCUSSION...

INITIALLY SEPARATED UPPER LEVEL CYCLONES -- NOW EVIDENT IN MOISTURE

CHANNEL IMAGERY OVER N-CENTRAL PACIFIC INVOF 40N AND INVOF ERN END

OF RUSSIA -- ARE FCST TO MERGE ACROSS NERN PACIFIC/GULF OF AK REGION

BY DAY-2. ECMWF/SPECTRAL/UKMET AND ALL BUT TWO MREF MEMBERS

INDICATE THAT MAJOR PORTION OF RESULTING CYCLONE SHOULD DIG SEWD

ACROSS PACIFIC NW AROUND DAY-5/29TH-30TH. PROGS DIVERGE

CONSIDERABLY THEREAFTER ON SIZE AND TRACK OF THIS LOW...WITH SOME

INDICATING MORE NRN EMPHASIS AND LOW CENTER OVER NRN ROCKIES/NRN

HIGH PLAINS...AND OTHERS WITH FURTHER AMPLIFICATION INTO GREAT BASIN

REGION. IN EITHER EVENT...ACCOMPANYING PROGRESSIVE/SYNOPTIC-SCALE

TROUGHING OVER WRN CONUS SHOULD LEAD TO ROBUST RETURN FLOW ACROSS

MUCH OF SRN/CENTRAL PLAINS...AS WELL AS STG LEE-SIDE TROUGHING

DAY-5. INTENSE CENTRAL HIGH PLAINS CYCLOGENESIS WITH WARM SECTOR

SVR POTENTIAL MAY OCCUR DAY-6/30TH-1ST AND/OR DAY-7/1ST-2ND.

UNCERTAINTIES REGARDING DEVELOPMENT/LOCATION OF STRONGEST DEEP-LAYER

FORCING PRECLUDE OUTLOOK ATTM...HOWEVER SOME PORTIONS SRN/CENTRAL

PLAINS MAY NEED ATTENTION FOR POSSIBLE OUTBREAK IN WHAT NOW IS DAY

6-7/30TH-2ND TIME FRAME.

When they mention Outbreak, this means a 3 day event is now Possible!

[Nick F]

Yes, 00z ECM this morning looking very good for this to occur next week, a slow moving troughy pattern developing over the mid-west after mid-week.

[Cakie]

Good News Paul

How reliable are these predictions? I hope for all of you it doesn't get downgraded. Keep us posted and I look forward to your reports back once you are over there

[Coast]

Pah, you wait and see what we have coming in the UK over the next month! (I'm not jealous )

[pottyprof]

Katie.. Seems that this year the mid range forecasts are very good. Its the detail that is a little wanting. But that's where we have Nick and Paul. Nick has had a 100% hit rate in the virtual chases..

[Gorky]

I have to say, this reminds me earily of last year.

Long range forecasts then showed ridging with a couple of models breaking this down at the 7 day mark. I remmeber Paul being worried and posting on Stormtrack asking for long range forecasts seemingly certain that death ridge was going to be in place for our arrival! . It has the potential for the same thing to happen here. The GFS has been pretty poor lately with it's mid range forecasts, so the euro model would be what I put my money on. notice the GFS has been trending towawrds the Euro with the alst few runs so thats a very positive sign. The setup for the end of next week looks pretty good if it maintains what is currently forecast.

If storms did hold off till Thursday it would be ideal for you I think. Whilst I'm sure it would be great to chase every day until you leave, a couple of warm up days before a big event were certainly appreciated last year. (Those warm up days last year were low end slight risks, which made anything you've ever seen here in the UK look like an April shower by the way!). Besides, if we had a May4th - May 6th event happen every day for 10 days, you would be dead from exhaustion at the end of it

[Paul Sherman]

Nathan

Funnily enough have been speaking to Paul about this today, saying last year although the Llano Storm was a Supercell it was Chaseable and we cut our teeth on it and the others though, hmm okay this is probably the equivalent of our worst Uk Storm ever And then May 4th Happened, we had our test Chases and we were really nailing it by then, this year it seems we might have a travel day and then a Full blown Supercell Day, to go from nothingness to Above Severe is going to be a Culture shock for the others who have not experienced this type of weather before. I am sure they will adapt quickly though and a few changes of Underwear with a stop in the Walmart should pass quickly.

Models currently look like having a Slight Risk on Wednesday somewhere in the C Plains or High Plains, before the main event on Thursday or Friday again in the Central to Southern Plains, a lot more Model runs before then though and a lot of chopping and changing to happen!

Great Outlook though!

Paul S

Some Charts for Thursday as they stand at the moment

[Gorky]

This is the last look I get before setting off on my way, as I leave here very early tomorrow mroning. The latest GFS run is pretty good for Thursday. In the order of 5000 cape under an originally strong but almost completely weakened cap in parts of Tx. Temp in the 90's Dews in the 80's. That a heck of a lot of potential energy waiting to be tapped into. That would be murder in the car without air con! Sure the mdoels show a slack period after for a few days but it doesn't take long to pick up again.

[kold weather]

Yeah doesn't look bad for Thursday just hope the cap isn't too weak to start otherwise it'll become a complete murk-fest, though even then with that sort of cape present the storms would still be severe esp if any supes do develop...

If the cap remains strong till peak heating then it will become very interesting however sadly a little too soon to know what will happen other then to say there is certainly a severe risk present, models right now look good enough to warrant a mod risk eventually...hope it doesn't bust like the last supposed severe outbreak!

Edited April 25, 2008 by kold weather

[Stu_London]

Bring it on

[Paul Sherman]

The S**T is going to Hit the Fan Middle Of Next Week!

DAY 4-8 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0352 AM CDT SAT APR 26 2008

VALID 291200Z - 041200Z

...DISCUSSION...

LARGE CYCLONE FCST TO EVOLVE OVER NWRN CONUS DURING DAY 4-5/29TH-1ST

TIME FRAME...INDUCING LEE TROUGHING AND EVENTUAL CYCLOGENESIS OVER

GREAT PLAINS. GEN PATTERN INDICATES MULTI-DAY SVR POSSIBILITIES

ALONG/E OF DRYLINE AND NEAR AND S OF WARM FRONT BEGINNING

DAY-5...THOUGH IMPORTANT DETAILS SUCH AS EML-RELATED CINH WILL BE

IMPORTANT FACTOR ESPECIALLY DURING FIRST DAY OR TWO OF THIS

SCENARIO. ECMWF -- ON AVERAGE THE MOST RELIABLE MODEL FOR THIS TIME

FRAME -- APPEARS TO BE SUBSTANTIAL OUTLIER COMPARED TO

UKMET/SPECTRAL AND ALL MREF MEMBERS WITH RESPECT TO MUCH MORE RAPID

AND SELY EJECTION OF PRIMARY SHORTWAVE FROM BASE OF NWRN CONUS

CYCLONE. THIS ALSO IS INCONSISTENT WITH SOME OF ITS OWN PREVIOUS

RUNS. THEREFORE WILL DOWNPLAY ECMWF FOR THIS FCST CYCLE AND WEIGH

OUTLOOK TOWARD MREF CONSENSUS. CONSIDERABLE LATITUDINAL VARIATION

EXISTS WITH BOTH MAGNITUDE/QUALITY OF MOISTURE RETURN AND PLACEMENT

OF DEEPENING SFC CYCLONE DAY-5/30TH-1ST...AMONGST MREF AND

SPECTRAL/UK RUNS. HOWEVER...STG AGREEMENT IN EXISTENCE OF THIS

LOW...AS WELL AS IN FAVORABLE MOISTENING LATE DAY-5 THROUGH

DAY-7/2ND-3RD...ENGENDERS HIGH CONFIDENCE IN WELL-ORGANIZED SVR

POSSIBLY INCLUDING AN OUTBREAK...AND COMPELS INTRODUCTION OF

CATEGORICAL OUTLOOKS. THESE AREAS ARE HIGHLY GENERALIZED AND

SUBJECT TO CONSIDERABLE SPATIAL REVISION AS OUTLOOK PERIODS DRAW

CLOSER.

[Paul]

[johnholmes]

stop panicking Paul its a PS wind up probably!

well maybe not

get the toilet paper

wait for PS to say its near then shut your eyes and stuff cotton wool in your ears, then watch the video afterwards over an ice cold beer.

Edited April 26, 2008 by johnholmes

[John Hanrahan]

woohoo!

[Hilton]

You should all be pleased to know we have a test with Howie Bluestein on Thursday morning, and traditionally that marks the start of a few days of good storms (eg. Greensburg last year), so good signs all round! Only 2 and a bit weeks left over here for us so we'd better get something good soon!

[Cookie]

looks great for next week