Model Watch For Tour 1

Paul Sherman · April 26, 2011

Eurgh

Latest from SPC Just out and not great reading. Seems they are not going one way or the other regarding Friday or Saturday at the moment. No idea on placement of the trough and when it is going to eject.

If GFS Wins out then Nebraska and S Dakota on Friday would be out of reach unless Tom and Ian take the other 10 off late Thursday night and stage the drive and reach the target for a bonus chase on Friday leaving me behind to pick up Mark (My turn to take 1 for the team :lol: )

If ECMWF Then i would imagine a chase for all on Saturday 30th April

DAY 4-8 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0355 AM CDT TUE APR 26 2011

VALID 291200Z - 041200Z

...DISCUSSION...

AS A COLD FRONT SHIFTS INTO THE WRN ATLANTIC AT THE START OF THE

MEDIUM-RANGE PERIOD...THE NEXT SYSTEM -- A WRN U.S. UPPER TROUGH --

SHOULD BE SHIFTING ACROSS THE INTERMOUNTAIN WEST. AS THE TROUGH

ADVANCES...A STRENGTHENING SURFACE SYSTEM IS PROGGED TO EMERGE INTO

THE PLAINS. HOWEVER...DIFFERENCES ARE EVIDENT IN THE HANDLING OF

THE UPPER TROUGH BETWEEN THE GFS AND ECMWF...WHICH AFFECT TIMING/

LOCATION OF THE SURFACE LOW AND ASSOCIATED FRONTAL SYSTEM EVOLUTION.

WHILE SOME SEVERE WEATHER POTENTIAL MAY EXIST DAY 4 /FRI. 4-29/--

POSSIBLY FOCUSED IN THE CENTRAL PLAINS...SOMEWHAT LIMITED MOISTURE

RETURN/DESTABILIZATION APPEARS LIKELY AHEAD OF THE SYSTEM.

FURTHER...DIFFERENCES IN THE MODELS...AND THEREFORE QUESTIONS

REGARDING TIMING AND MAGNITUDE OF THE POTENTIAL CONVECTIVE

EVENT...PRECLUDE HIGHLIGHTING AN OUTLOOK AREA ATTM.

THE MODEL DIFFERENCES CONTINUE BEYOND DAY 4...WITH INCREASES IN THE

DEGREE OF MODEL DIVERGENCE EVIDENT. THUS...WHILE THE FRONTAL SYSTEM

WILL CONTINUE EWD WITH TIME -- POSSIBLY ACCOMPANIED BY SOME SEVERE

THREAT...HIGHLIGHTING OF ANY POTENTIAL THREAT AREAS WILL NOT BE

ATTEMPTED AT THIS TIME.

**Nick F** · April 26, 2011

Saturday does look the first realistic day for a good chase atm, both ECM and GFS show better moisture return than Friday across southern/central plains over to the Mississippi Valley with falling heights from the west and a strong low-level jet from the south. That's not to say there could be a bonus day on Friday, but atm the severe potential could be out of reach over central/northern plains.

After Saturday, 00z GFS and ECM suggest the cold front will sag S towards southern/SE Texas and move SE across the Gulf States further east, with a surface ridge building in behind across the Plains into early next week, but given the increasing model uncertainty beyond Friday, there's still room for change.

Paul Sherman · April 26, 2011

Yep

It does not look like the traditional Alley is going to fire anytime soon tbh.

After Friday and Saturday not seeing much potential in the medium range models until the following weekend, as Nick says all subject to change and if the SPC & Models cant agree at Day 4 what chance at days 7 or 8 :wacko:

Dorsetbred · April 26, 2011

Yep

It does not look like the traditional Alley is going to fire anytime soon tbh.

After Friday and Saturday not seeing much potential in the medium range models until the following weekend, as Nick says all subject to change and if the SPC & Models cant agree at Day 4 what chance at days 7 or 8 :wacko:

Fresh snow on the Webcam in Breckenridge

Now the plus side of this is that local Dallas weather is now going for 20% chance of storms on Sat & Sun, which was it's rating for yesterday, and look what happened then

Edited April 26, 2011 by Dorsetbred

Paul Sherman · April 26, 2011

But 06z GFS Now coming through starting to give an indication that Saturday is going to be the day rather than Friday. Wait a mo and I will update some charts from the 06z before wrist slitting commences

- 3,500 to 4,000jkg of Cape

- Suntan before the Cap Breaks

- Very Good Moisture

- How apt, Supercell breaks out just North of Fort Worth

**Nick F** · April 26, 2011

Lol, at least you won't have far to go to position for the 1st Chase. Could be similar area if a little further east and SE on Sunday as the cold front sags south and SE. Long way-off yet to firm things up though.

Paul Sherman · April 26, 2011

Lol I am liking the Sherman area for Saturday Lets see if the SPC Introduce a Day4 tomorrow I have a feeling they might.

Also could tick off another first and see my first ever April Tornado After my 1st June Tornado last year.

I like the Shortwave coming through from the Texas Panhandle on 30th as well.

Dorsetbred · April 26, 2011

That update seems a :D on the smiley graph

nsrobins · April 26, 2011

GFS still looks a tad progressive for the Saturday window but there is little cross-model agreement, hence the 'predictability too low'.

I think some sort of activity will develop Fri/Sat/Sun followed by a few quiet days before re-load mid week.

Roger J Smith · April 26, 2011

Improving prospects for Saturday evening with the main question being development before or after sunset (03z 1 May) across the TX panhandle region into western OK. I'm expecting moderate risk to be posted for this event by Thursday and it could go borderline strong outbreak by chase time. Very early call on chase location, from west to east through Plainview TX towards Clinton OK. (30:23z to 1:03z evening of Sat 30 Apr local time).

Dorsetbred · April 27, 2011

WFAA now increased the storm opportunity for Sat & Sunday, so both now look to be "opportunities".

After that tho

Edited April 27, 2011 by Dorsetbred

Paul Sherman · April 27, 2011

After that tho

Quent

I am going to have to sit down with you and go through reading the models mate

I can see marginal chase opps which could be upgraded in 4 or 5 days time on the 3rd and 4th in the Northern Plains (Dakotas and Minnesota) associated with an area of Low Pressure moving across the Candian Border.

There is also another LP Bombing across the C Plains for the 6th and 7th

What are you seeing different and at that range this can change quickly for better or worse.

jimbo36 · April 27, 2011

Good luck to all on Tour 1.

I'm counting down the days for Tour 4 and looking forward to it.

Does anyone know if the storm chasing documentary following Fishy is still on?

Jimbo

Dorsetbred · April 27, 2011

Quent

I am going to have to sit down with you and go through reading the models mate

I can see marginal chase opps which could be upgraded in 4 or 5 days time on the 3rd and 4th in the Northern Plains (Dakotas and Minnesota) associated with an area of Low Pressure moving across the Candian Border.

There is also another LP Bombing across the C Plains for the 6th and 7th

What are you seeing different and at that range this can change quickly for better or worse.

Paul

Don't disagree with any of the above, as they are as you mentioned some time ago with the low going into the Dakotas.

I'm not seeing anything different as I said "After that tho..." I meant that as a open question

It's still all to play and looking towards the cyclic spell of couple days on and couple days off.

Going back to eHow to brush up on the how to read models

Ps appreciate the onsite training offer

Edited April 27, 2011 by Dorsetbred

Paul Sherman · April 27, 2011

Not much of a chance of Tornadoes from the latest outlook unfortunately. SPC Saying only elevated Storms on Saturday in the areas we have been watching and again the same on Sunday further east with all the parameters not being condusive for Tornadoes, but at least some Thunderstorms over the first few days. Pretty quiet after that upto middle of next week as well.

Seems April was the New May!

DAY 4-8 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0355 AM CDT WED APR 27 2011

VALID 301200Z - 051200Z

...DISCUSSION...

MEDIUM-RANGE MODELS IN DECENT AGREEMENT THROUGH ROUGHLY DAY 6 /MON.

5-2/...IN PROGRESSING A LARGE UPPER TROUGH SLOWLY EWD ACROSS THE

CENTRAL CONUS.

AS A SURFACE FRONT ADVANCES INTO THE UPPER GREAT LAKES/MIDWEST DAY 4

/SAT. 4-30/...IT APPEARS THAT A LACK OF RICHER LOW-LEVEL MOISTURE --

STILL CONFINED TO AREAS FARTHER S -- MAY PRECLUDE SUBSTANTIAL SEVERE

THREAT FROM MO NWD. MORE FAVORABLE SEVERE WEATHER ENVIRONMENT WILL

LIKELY EVOLVE FARTHER S HOWEVER INTO THE SRN PLAINS...AS A SECONDARY

LOW APPEARS LIKELY TO DEVELOP ALONG THE FRONT AS A SECOND PIECE OF

ENERGY ROTATES AROUND THE BASE OF THE MAIN UPPER TROUGH. MODELS DO

DIFFER HOWEVER IN LOCATION OF THE SECONDARY LOW DEVELOPMENT. WITH

ENHANCED LOW-LEVEL WIND FIELD ASSOCIATED WITH THIS LOW LIKELY TO BE

A PRIMARY DRIVER OF GREATER SEVERE WEATHER POTENTIAL...WILL NOT

INTRODUCE A THREAT AREA ATTM DESPITE ELEVATED POTENTIAL APPARENT

SOMEWHERE IN THE SRN OK/NRN AND CENTRAL TX AREA.

THREAT WILL SHIFT EWD DAY 5 /SUN. 5-1/ -- WITH GREATEST POTENTIAL

LIKELY TO RESIDE SOMEWHERE FROM THE TN VALLEY REGION SWWD INTO THE

LOWER MS VALLEY. HOWEVER...SOMEWHAT WEAKER WIND FIELD OVER SRN

PORTIONS OF THE REGION WHERE GREATER MOISTURE/INSTABILITY IS LIKELY

BUT LESS FAVORABLE THERMODYNAMICS FARTHER N WHERE THE MORE FAVORABLE

KINEMATIC CONDITIONS SHOULD RESIDE PRECLUDE FORECAST OF A HIGHER-END

THREAT AREA ATTM.

WITH THE FRONT PROGGED TO CONTINUE EWD DAY 6...CONVECTIVE POTENTIAL

SHOULD LIKEWISE SHIFT INTO THE ERN QUARTER OF THE COUNTRY.

HOWEVER...EVEN LESS FAVORABLE THERMODYNAMIC CONDITIONS ARE EXPECTED

ATTM.

FINALLY...DIFFERENCES IN THE MODELS DAY 7-8 WITH HANDLING THE

EVENTUAL DEPARTURE OF THIS FRONT OFF THE E COAST CAST UNCERTAINTY

ONTO THE CONVECTIVE POTENTIAL LATE IN THE PERIOD.

Paul Sherman · April 27, 2011

Obviously the above not set in stone and things can change before Saturday and become more favourable for Tornadoes but if anything else make sure those cameras are charged as Elevated Thunderstorm give some amazing Lightning opportunities and Large Hail!

TornadoJo · April 27, 2011

Well, anything is better than nothing and even nothing is better than being stuck in the office so chin up everyone. We're going to have a fab time.

Oh and weather gods.. ... Please? Lots of kisses and you can have my last rolo.

Gorky · April 27, 2011

I think the mention of 'despite elevated potential' in the SPC outlook probably means 'despite increased potential' rather than actual elevated storms. Whilst forecast LCL's are not exactly low, they are not so high as to rule out tornadoes or other severe. Dews in the low to mid 70's, temps in the mid to high 80's are fine. The Red River Valley north of DFW seems a fine play on the current GFS at the moment for this day though it'll likely change

Roger J Smith · April 28, 2011

Paul, looks at this point as if SPS to nw FTW would be ground zero on Saturday afternoon/evening. Could be a major outbreak and tornadic although caution due to back-door cold front type evolution. Would expect line of TRW+ late afternoon north of an arc LBB-SPS-ADM shifting south and accelerating. Dangerous chase situation given potential for storms to over-run viewing locations. Wild card is major energy infusion after 00z May 1st. Will keep a close eye on this and update but this looks like the classic storm-chase-you situation.

**Nick F** · April 28, 2011

Slight risk for tour 1 on Saturday across north central TX, a short trek to the Red River Valley for the guys and gals. Storms still look like being mainly elevated atm, but opportunities for large hail and lightning shots:

http://www.spc.noaa.gov/products/outlook/day3otlk.html

DAY 3 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0224 AM CDT THU APR 28 2011

VALID 301200Z - 011200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF N TX AND

ADJACENT SRN OK...

...SYNOPSIS...

A WRN U.S. UPPER TROUGH IS FORECAST TO CONTINUE SLOWLY

DIGGING/PROGRESSING EWD/SEWD WITH TIME...DISASSEMBLING INTO TO

SMALLER-SCALE TROUGHS WITH TIME -- A MORE NRN SHORT-WAVE FEATURE

MOVING MORE QUICKLY ACROSS THE UPPER MS VALLEY REGION AND INTO THE

UPPER GREAT LAKES LATE...AND A SECOND FEATURE WHICH WILL CONTINUE

SLOWLY DIGGING SSEWD OUT OF THE GREAT BASIN INTO AZ/NM.

AS THE UPPER SYSTEM EVOLVES...THE NRN PORTION OF THE SURFACE COLD

FRONT CROSSING THE PLAINS WILL CONTINUE EWD ACROSS THE N CENTRAL

PORTION OF THE CONUS...CROSSING THE UPPER GREAT LAKES/UPPER MIDWEST

LATE. MEANWHILE...THE FRONT SHOULD MOVE MUCH MORE SLOWLY SEWD

ACROSS THE SRN PLAINS...LIKELY SLOWING OR EVEN STALLING AND LAYING

OUT ROUGHLY W-E ACROSS N TX BY LATE IN THE PERIOD. WHILE SHOWERS

AND A FEW THUNDERSTORMS WILL BE POSSIBLE ALONG THE FRONT FROM THE

UPPER MIDWEST SWWD INTO THE ARKLATEX REGION DURING THE DAY...MAIN

SEVERE POTENTIAL SHOULD EVOLVE LATE IN THE PERIOD OVER PARTS OF

TX/OK IN CONJUNCTION WITH THE DEVELOPING LOW-LEVEL JET.

...RED RIVER VALLEY REGION OF SRN OK/N TX...

AS UPPER HEIGHTS FALL ACROSS THE SRN PLAINS REGION AHEAD OF THE MAIN

TROUGH...STRONG SLY LOW-LEVEL JET IS FORECAST TO DEVELOP IN RESPONSE

DURING THE EVENING HOURS OF DAY 3 /SAT. 4-30/ OVER CENTRAL AND N TX.

WITH THE ROUGHLY W-E PORTION OF THE SURFACE FRONT PROGGED TO LIE

ACROSS N TX DURING THE SECOND HALF OF THE PERIOD...STRONG ISENTROPIC

LIFT/WARM ADVECTION SHOULD LEAD TO AN INCREASE IN COVERAGE OF

ELEVATED STORMS. WITH RELATIVELY STEEP LAPSE RATES ALOFT AND 50 KT

WSWLY MID-LEVEL FLOW EXPECTED...SHEAR/INSTABILITY COMBINATION

APPEARS SUFFICIENT TO SUPPORT THREAT FOR HAIL WITH A FEW

STRONGER/POSSIBLY ROTATING STORMS.

multi cellular thunderstorm · April 28, 2011

Latest 4-8 day outlook, and seems like a lot of uncertainty.

They're not saying much...

DAY 4-8 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0351 AM CDT THU APR 28 2011

VALID 011200Z - 061200Z

...DISCUSSION...

SYNOPTIC-SCALE PREDICTABILITY IN THE MEDIUM-RANGE PERIOD REMAINS LOW

THIS FORECAST...WITH SUBSTANTIAL DIFFERENCES IN THE MODELS WITH

RESPECT TO THE PROGRESSION OF A LARGE UPPER TROUGH ACROSS THE

CENTRAL AND ERN U.S. -- AND THUS THE ADVANCEMENT OF AN ASSOCIATED

COLD FRONT -- EVEN AS EARLY AS DAY 4 /SUN. 5-1/. DURING THE

AFTERNOON OF DAY 4...THE FRONT IS PROGGED BY THE GFS TO LIE FROM ERN

NY/CENTRAL PA SWWD TO THE TX COAST...WHILE THE ECMWF SHOWS THE FRONT

AT THE SAME TIME LYING FROM WRN OHIO SWWD INTO SERN LA.

WITH DIFFERENCES THIS SUBSTANTIAL DAY 4 -- AND CONTINUING

BEYOND...WILL NOT ATTEMPT TO HIGHLIGHT ANY SEVERE WEATHER THREAT

AREAS THIS FORECAST.

..GOSS.. 04/28/2011

Dorsetbred · April 28, 2011

Nick

Thanks for the updates, whilst the rest of tour 1 are soaking their feet in Weatherspoons, I thought I'd check in and see what the update looked like.

Much appreciated.

MCT. Don't bring that forecast with you

Edited April 28, 2011 by Dorsetbred

nsrobins · April 28, 2011

Really best of british to the chase teams as they begin their adventure.

Reasonable set-up Gainesville/Wichita Sat eve now and some good structure to be found at least.

I wouldn't rule out some tornado potential but it's a tad too early to be sure.

NL · April 28, 2011