Virtual Storm Chase 3

[Paul Sherman]

Getting into the Timeframe where we look ahead at our 1st Chase Day on 29th April 2008.

Obviously this will chop and change, but if this stays the same then the Participants will be very happy with a Texas Panhandle Chase on Day 1

- Dryline Magic

- Plenty of Energy and Moisture

- Roaring Jet Stream aloft!

- 34c 95f

Paul Sherman

[Gorky]

That trough has been there Tuesday or Wednesday for the last 4 runs also so it;s not a one time only thing. I'll try not to get too excited given how far it is into FI but I'd just love for that to come through. Temps into the low 80's Dews into the low 70s, decent upper level winds, a strong LLJ feeding into a 996mb low over E Co / W KS, with a decent strength cap which weakens by sunset would be a perfect setup I'm certain it will probably disappear entirely on future runs being so far out of course

[Gorky]

Just another date to note, and Tuesday 22nd is looking insane if tonights forecast verifies. This date has been on the card for a good 4 days now with very little change in the GFS model at least.

990mb low in SE CO, warm front stretching up to Wisconsin and into Canada, with capping eroding by the end of the day in a large part of the huge warm sector with 70's dews. 60's F dewpoints all the way north to Canada also. A nice well pronounced dryline down to Mexico through eastern TX panhandle. This could be a widespread severe weather day for sure. The GFS has nailed most of the big events a week out so I guess we'll see how this one goes. It certainly makes me wish I'd booked my trip a week early looking at it! It would have been a great birthday present to be out there if this sort of event was to actually transpire

[Paul Sherman]

As expected a few days ago SPC Upgraded today and Tomorrow to a Slight Risk, mainly large Hail with only a 2% Tornado Risk, if we were there I would be sitting in Alva for today.

DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1233 AM CDT WED APR 16 2008

VALID 161200Z - 171200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF SWRN AND CNTRL

KS AND A SMALL PART OF NWRN OK...

...SYNOPSIS...

MIDLEVEL TROUGH INITIALLY FROM THE CANADIAN PRAIRIES SWWD INTO THE

LOWER CO VALLEY WILL ELONGATE AND EVENTUALLY FRACTURE AS MORE

PROGRESSIVE NRN BRANCH OF TROUGH MOVES EWD TOWARDS HUDSON BAY AND

THE UPPER GREAT LAKES. MEANWHILE...SRN PORTION OF TROUGH WILL

AMPLIFY AS UPSTREAM JET STREAK /CURRENTLY OVER THE SIERRA NEVADA/

ROUNDS THE TROUGH BASE...SUPPORTING A CONCENTRATED AREA OF HEIGHT

FALLS FROM THE FOUR CORNERS REGION EWD INTO THE CNTRL AND SRN HIGH

PLAINS.

IN THE LOW LEVELS...SURFACE LOW ATTENDANT TO EVOLVING NRN BRANCH

TROUGH WILL DEVELOP FROM NRN MN NEWD INTO CNTRL ONTARIO WHILE

TRAILING COLD FRONT PUSHES EWD INTO THE UPPER GREAT LAKES. SWRN

EXTENSION OF FRONT WILL SLOW IT/S SWD PROGRESS OVER THE SRN HIGH

PLAINS IN RESPONSE TO CYCLOGENESIS OVER NERN NM INTO THE OK/TX

PNHDLS. MEANWHILE...A DRYLINE WILL SHARPEN THROUGH THE DAY FROM

INTERSECTION WITH THE FRONT OVER NWRN OK OR THE ERN OK/TX PNHDLS SWD

INTO W-CNTRL TX.

...OK/KS...

16/00Z OBSERVED SOUNDINGS FROM S TX AND CURRENT SURFACE/BUOY DATA

INDICATE A MODIFIED CONTINENTAL AIR MASS RETURNING NWD THROUGH THE

WRN GULF OF MEXICO AND TX WITH DEWPOINTS INCREASING INTO THE

LOWER/MID 50S. CYCLOGENESIS OVER THE SRN HIGH PLAINS WILL SUPPORT

THE NWD ADVECTION OF SIMILAR BOUNDARY LAYER MOISTURE THROUGH OK INTO

SRN KS BENEATH A WELL-DEFINED EML AND RESULTANT STRONG CAP. THIS

CAP WILL LIKELY SUPPRESS ANY SURFACE-BASED...DIURNAL TSTM

DEVELOPMENT ALONG THE DRYLINE AND SURFACE FRONT.

TSTMS /LIKELY SLIGHTLY ELEVATED/ ARE EXPECTED TO DEVELOP BETWEEN

17/00Z-17/03Z NEAR THE INTERSECTION OF DRYLINE AND SURFACE FRONT

OVER NWRN OK OR SWRN KS. HERE...CAP SHOULD BE LOCALLY OVERCOME AS

RAPIDLY STRENGTHENING LLJ ENHANCES CONVERGENCE ALONG AND JUST N OF

LOW-LEVEL BAROCLINIC ZONE. THE PRESENCE OF STEEP LAPSE RATES AND

POTENTIALLY MODERATE INSTABILITY /MUCAPES APPROACHING 1000-1300 J

PER KG/ IN CONJUNCTION WITH RELATIVELY STRONG CLOUD BEARING SHEAR

SUGGEST THE POTENTIAL FOR A FEW ORGANIZED/ROTATING STORMS CAPABLE OF

MAINLY LARGE HAIL.

UPSCALE GROWTH INTO ONE OR MORE...ELEVATED TSTM CLUSTERS IS EXPECTED

TO OCCUR ACROSS KS OVERNIGHT WITH THIS ACTIVITY MOVING/DEVELOPING

NEWD TOWARD THE LOWER MO VALLEY BY THURSDAY MORNING. SOME HAIL WILL

REMAIN POSSIBLE WITH THE MOST INTENSE STORMS.

[Nick F]

Think I'm going to Virtual Chase today's SLIGHT risk, 5% risk of a tornado from TX Hill Country up across DFW and into south central OK. Dry line looks like it will come into play across central/SW TX by 00z - any storms forming ahead of this towards TX Hill country will be utilising the best of the moisture return and MLCAPE values:

... so think I will target Brady, TX for today.

DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1246 AM CDT THU APR 17 2008

VALID 171200Z - 181200Z

...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS S-CENTRAL TX NNEWD

ACROSS PORTIONS CENTRAL/NERN OK....

...SYNOPSIS...

SYNOPTIC PATTERN ALOFT FEATURES BROAD CYCLONIC GYRE CENTERED

OFFSHORE CAROLINAS...POSITIVELY TILTED RIDGE FROM SERN CANADA TO

N-CENTRAL GULF OF MEXICO...AND TROUGHING FROM HUDSON BAY SWWD ACROSS

AZ TO NWRN MEX. STG SHORTWAVE PERTURBATION -- EVIDENT IN MOISTURE

CHANNEL IMAGERY OVER 4-CORNERS REGION -- IS MOVING THROUGH BASE OF

LARGER SCALE TROUGH...AND SHOULD EJECT ENEWD TO NEWD ACROSS

S-CENTRAL PLAINS AS CLOSED LOW THIS PERIOD. OPERATIONAL

SPECTRAL/WRF AGREE WITH EACH OTHER ON 500 MB LOW POSITION NEAR MHK

BY 18/12Z...BUT THIS IS ABOUT 200 NM NE OF CONSENSUS SREF POSITION

OVER NWRN ON NEAR KS BORDER....LATTER BEING PREFERRED FOR THIS FCST

BASED ON CURRENT SATELLITE TRENDS.

AT SFC...FRONTAL ZONE INITIALLY WAS ANALYZED FROM LS SWWD ACROSS SRN

IA...NWRN MO...S-CENTRAL/SWRN KS...AND N-CENTRAL-W-CENTRAL TX

PANHANDLE...INTO SFC LOW LOCATED ROUGHLY BETWEEN CAO-TCC. THIS LOW

IS EXPECTED TO EJECT EWD THEN NEWD ALONG SFC FRONT...MOVING FROM

NWRN OK AROUND 17/12Z TO SERN KS DURING EVENING. AS THIS

OCCURS...SFC COLD FRONT SHOULD MOVE SWD OVER SRN HIGH PLAINS.

WEAK/SECONDARY LOW MAY DEVELOP INVOF COLD FRONT/DRYLINE INTERSECTION

THIS AFTERNOON ACROSS NW TX...WITH DRYLINE EXTENDING SSWWD INTO SFC

LOW OVER NRN COAHUILA.

...CENTRAL/SRN PLAINS...

SCATTERED TSTMS ARE EXPECTED TO DEVELOP DURING AFTERNOON INVOF SFC

FRONTAL ZONE OVER OK...GENERALLY BECOMING MORE LINEAR AND

BACKBUILDING SWD WITH TIME THROUGH EVENING AS REGIME SHIFTS EWD

ACROSS OK AND N-CENTRAL TX. DEEP-LAYER SHEAR PROFILES WILL BE

FAVORABLE FOR SUPERCELLS....ALTHOUGH DISCRETE STORM MODES MAY NOT BE

MAINTAINED FOR VERY LONG GIVEN STRONGLY PARALLEL COMPONENT OF MEAN

FLOW ALOFT WITH RESPECT TO FRONTAL FORCING ZONE. ANY SUSTAINED

SUPERCELLS MAY PRODUCE LARGE HAIL AND SVR GUSTS...ALONG WITH SLGT

TORNADO THREAT. AS SOURCE REGION RETURN FLOW AIR MASS CONTINUES TO

MODIFY SLOWLY...MOISTURE WILL ADVECT NWD ACROSS CENTRAL/NRN TX AND

OK...TO BE MODULATED SOMEWHAT DURING AFTERNOON BY VERTICAL MIXING

PROCESSES. EXPECT SFC DEW POINTS MID-UPPER 50S ACROSS MOST OF SERN

KS AND ERN OK...LOW 60S S-CENTRAL/SERN OK AND MID 60S CENTRAL/SRN TX

BY 17/21Z. MLCAPES TO NEAR 1500 J/KG ARE POSSIBLE AS A RESULT.

INITIALLY SEPARATE AREA OF TSTMS....AND SVR POTENTIAL...MAY DEVELOP

LATE AFTERNOON INTO EARLY EVENING OVER HILL COUNTRY AND ERN EDWARDS

PLATEAU REGIONS OF TX. THIS AREA WILL BE CHARACTERIZED BY FAVORABLE

LOW LEVEL MOISTURE AND STRONGEST SFC HEATING WITHIN OUTLOOK

AREA...SUPPORTING MLCAPES 1500-2000 J/KG E OF DRYLINE. SOMEWHAT

DRIER AND MORE WELL MIXED BOUNDARY LAYER NEAR DRYLINE WILL SUPPORT

AROUND 1000 J/KG MLCAPE DURING MOST PROBABLE TIME OF INITIATION --

22-01Z. HOWEVER...MOIST ADVECTION AND LOSS OF MIXING SHOULD LOWER

LCL DURING EARLY EVENING...SUCH THAT EFFECTIVE INFLOW PARCELS STAY

SFC-BASED FOR ROUGHLY 3-4 HOUR TIME WINDOW UNTIL SFC LAYER

SUFFICIENTLY COOLS TO ELEVATE THEM.

[Paul Sherman]

Looks like Monday and Tuesday for the next real shot at an outbreak, again the same areas look to get hit with N Central Texas, S Oklahoma, E Oklahoma and the Ozarks in the firing line. The 1st threat is for the Northern Plains with a Plunging CF, Gulf Moisture returns as the system ejects and the S Plains are the places to be for the High End Severe threat probably on Tuesday 22nd April.

DAY 4-8 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0304 AM CDT THU APR 17 2008

VALID 201200Z - 251200Z

...DISCUSSION...

MODEL AGREEMENT APPEARS TO HAVE BECOME SUFFICIENT THIS PERIOD TO

BEGIN TO HONE IN ON SEVERE POTENTIAL IN BOTH SPACE AND TIME. MODELS

HAVE HINTED AT A SEVERE POTENTIAL OVER THE PLAINS FOR SEVERAL

DAYS...AS THEY HAVE BEEN CONSISTENT IN DEVELOPING A LARGE TROUGH

OVER THE WEST...AND DOWNSTREAM CYCLONIC FLOW ACROSS THE PLAINS.

WHILE THEY HAVE DIFFERED IN THE DETAILS OF THE EJECTION OF THIS

TROUGH INTO CENTRAL NOAM...THERE IS NOW SOME AGREEMENT THAT THE

FIRST SIGNIFICANT PIECE OF THIS TROUGH SHOULD MOVE SLOWLY NEWD

ACROSS THE ROCKIES AND THEN INTO THE NRN PLAINS DURING THE DAY 4-5

PERIOD. AS THIS OCCURS...A FAIRLY STRONG COLD FRONT SHOULD MOVE EWD

ACROSS THE NRN AND CENTRAL PLAINS. BOTH THE ECMWF AND GFS SUGGEST

THAT BY THE AFTERNOON OF DAY 5 /MON. APR. 21/ THE FRONT SHOULD

EXTEND FROM THE UPPER MS VALLEY/WRN UPPER GREAT LAKES SSWWD INTO THE

OZARKS REGION...AND THEN TRAILING MORE W-E ACROSS OK. THIS BOUNDARY

IS THEN FORECAST TO LINGER ACROSS OK/N TX DAY 6.

AS THE FRONT LINGERS ACROSS THE SRN PLAINS DAY 5-6...MODELS INDICATE

SEVERAL SMALLER-SCALE FEATURES SHIFTING ENEWD INTO THE SRN PLAINS IN

MODERATELY-STRONG WSWLY SRN STREAM S OF THE MAIN TROUGH/JET. WITH

THE LIKELIHOOD FOR RICH GULF MOISTURE BENEATH STEEP LAPSE RATES

ALOFT...INSTABILITY/SHEAR COMBINATION SHOULD BE QUITE SUPPORTIVE OF

SOME HIGHER-END SEVERE POTENTIAL. WITH THE CURRENT MODEL RUNS

POINTING AT DAYS 5 AND 6 AS THE PERIOD OF GREATEST THREAT...AND THE

SRN PLAINS REGION AS THE AREA OF GREATEST POTENTIAL...WILL INTRODUCE

A THREAT AREA IN THIS REGION.

[kold weather]

Yep around the 21st and 22nd has been progged by the GFS quite consitantly and its ensembles have been in agreement about a strong low driving into the plains region. However the upper jet isnt quite as potent looking which may turn out to be a good thing because last outbreak it just tore apart any cells that got above 30-33,000 feet.

[NL]

At last a virtual stormchase, think i'll head a bit more south than Nick and hang around

Medina, Texas. Storms likely to initiate around 5pm-7pm their time 10pm-1am our time.

[Nick F]

Going to risk a chase in Texas Hill Country eh NL

We ended up down that way on our 2nd chase day last year - though a little further north chasing Junction to Rock Springs. Hilly terrain thick with low trees and cactus, road options are limited too ... not ideal, but maybe not as bad as Nern Arkansas and Sern Misery.

[NL]

Going to risk a chase in Texas Hill Country eh NL

We ended up down that way on our 2nd chase day last year - though a little further north chasing Junction to Rock Springs. Hilly terrain thick with low trees and cactus, road options are limited too ... not ideal, but maybe not as bad as Nern Arkansas and Sern Misery.

Yeah, had a look on Google earth at the terrain around there and thought it looks a tad hilly, but today i have a

supercharged 180ft cherrypicker to chase with.!! ..

[Paul Sherman]

Yeah, had a look on Google earth at the terrain around there and thought it looks a tad hilly, but today i have a

supercharged 180ft cherrypicker to chase with.!! :lol: ..

I am chasing today with the Gadgetmobile!

GO GO GADGET LEGS

As a side note if the GFS Is to be believed then we should pack the Ice Picks on our arrival in under 2 weeks, 0c in Colorado and about 8c in the Panhandles :lol:

[Nick F]

Some decent Tds (dew points) advecting in across Sern Texas now 61-63F with temps reaching 80F, much drier air evident over far west TX towards El Paso with Tds below 20F west of the eastward moving dry line:

Dry line looks to be arriving in a line due SW of Abilene around 00z tonight looking at RUC Td progs with my own drawing of fronts on it, Triple Point of Dry line and Cold front somwhere around Abilene:

Some decent CAPE building up in the warm sector ahead of dry line, a chase S and SW of Abilene may result in some discrete supercells forming near dry line ... further north along cold front most likely to be a linear squall line developing which will eventually move SE across Texas tomorrow morning:

Wind shear vectors and helicity perhaps improving towards Nern TX - though still should support an isolated weak tornado over Sern central TX in any discrete cells.

[Hilton]

I'm heading south from Norman in a bit. Not hoping to see that much, but the cloud is clearing nicely here so should have a chance to see some good development this afternoon. (Have loads of work to try and get out of the way so I can play next week, so any trip today will be nice and local).

[Paul Sherman]

Shackleford County does it again, 1st of the days cells exploded near to Throckmorton, but after going severe within 20 minutes it may be the wrong side of where the better environment is already and looks to be struggling.

Must have been a sight to see that go from Cumulus to 30k within 20 minutes though!

Paul S

**Looks like a very slim window to get a Nado today, I would favour somewhere east of I35 Before the surging Cold Front with its SE Moving Squall line kills everything today.

Paul S

[Mammatus]

Shackleford County does it again, 1st of the days cells exploded near to Throckmorton, but after going severe within 20 minutes it may be the wrong side of where the better environment is already and looks to be struggling.

Must have been a sight to see that go from Cumulus to 30k within 20 minutes though!

Paul S

**Looks like a very slim window to get a Nado today, I would favour somewhere east of I35 Before the surging Cold Front with its SE Moving Squall line kills everything today.

Paul S

Quite Paul

I'm not quite sure where I'm currently heading Will be researching US map over the coming weeks.

Mammatus

[Nick F]

Convection forming between Abilene and Red River NE of Witchita Falls seems to be developing along the cold front ... got a feeling it will turn into a much larger linear squall line as it continues SE perhaps turning severe over north central TX and south central OK ... this is where 0-1km SR Helicity values and wind shear vectors are at their strongest also - though nothing to write home about and not really going to produce any strong tornadoes:

Initiation along dry-line looking a bit iffy atm, seems a stronger cap S and SW of Abilene though still a good few hours yet of day-time heating ... big downside of this area is lack of LL wind shear/helicity ... so tornadoes seem less likely than further NE - as the charts above show.

[Paul Sherman]

http://www.severestudios.com/cgi-bin/strea...name=roger.hill - Silver Lining Tours - Tour 1 - Day 1

Might take some time to load!

Paul S

[Paul Sherman]

Possible Hook on the Cell South of Wichita Falls on the 1645 radar scan, Cell now Severe Warned again!

Paul S

[Nick F]

Yes, looks like the only supercell around so far - robbing the energy from the other line convection now, NE of Graham near a town called Loving!

[Paul Sherman]

Rotation showing in the Mid Levels as well - Could spring a surprise this one Nick!

BULLETIN - EAS ACTIVATION REQUESTED

SEVERE THUNDERSTORM WARNING

NATIONAL WEATHER SERVICE FORT WORTH TX

451 PM CDT THU APR 17 2008

THE NATIONAL WEATHER SERVICE IN FORT WORTH HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...

JACK COUNTY IN NORTH CENTRAL TEXAS...

* UNTIL 545 PM CDT

* AT 451 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A

SEVERE THUNDERSTORM CAPABLE OF PRODUCING GOLF BALL SIZE HAIL...AND

DAMAGING WINDS IN EXCESS OF 60 MPH. THIS STORM WAS LOCATED 12

MILES NORTHWEST OF BRYSON...AND MOVING EAST AT 40 MPH.

* OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO

JACKSBORO

FOR YOUR PROTECTION MOVE TO A STURDY SHELTER AND STAY AWAY FROM

WINDOWS UNTIL THE STORM HAS PASSED.

THIS STORM HAS A HISTORY OF PRODUCING LARGE HAIL. SEEK SHELTER NOW

INSIDE A STURDY STRUCTURE AND STAY AWAY FROM WINDOWS!

[Nick F]

Appears to be starting to right-move and maybe split in two aswell Paul, could be interesting as it starts to draw better moisture away from the cold front and surface winds back more (create more directional shear) as it heads more eastwards:

[Paul Sherman]

This is why Slight Risks should NEVER Be ignored, this cell has raced ahead of the front and is moving into a SRH Environment not to dis-similar to last weeks Moderate Risk event.

BTW That arrow is pointing straight at............................ :o :blink: Me lovely COW CAMP Steakhouse!!!

Paul S

[Nick F]

Yep, even Text forecast areas shouldn't be ignored for chase potential if dynamics are borderlining into severe risk territory.

Cell further SW towards Breckenridge got a TVS on it - this area seems to be a hotbed for storms recently:

[Paul Sherman]

As Nick says, the same areas getting hit this year, Only upto Golf Balls at the moment, no Baseballs or Softballs.............YET

BULLETIN - EAS ACTIVATION REQUESTED

SEVERE THUNDERSTORM WARNING

NATIONAL WEATHER SERVICE FORT WORTH TX

531 PM CDT THU APR 17 2008

THE NATIONAL WEATHER SERVICE IN FORT WORTH HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...

NORTHERN PALO PINTO COUNTY IN NORTH CENTRAL TEXAS...

* UNTIL 630 PM CDT

* AT 531 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A

SEVERE THUNDERSTORM CAPABLE OF PRODUCING GOLF BALL SIZE HAIL...AND

DAMAGING WINDS IN EXCESS OF 60 MPH. THIS STORM WAS LOCATED 7 MILES

WEST OF POSSUM KINGDOM STATE PARK...AND MOVING EAST AT 44 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...

GRAFORD BY 600 PM

MINERAL WELLS BY 610 PM

FOR YOUR PROTECTION MOVE TO A STURDY SHELTER AND STAY AWAY FROM

WINDOWS UNTIL THE STORM HAS PASSED.

THIS STORM HAS A HISTORY OF PRODUCING LARGE HAIL. SEEK SHELTER NOW

INSIDE A STURDY STRUCTURE AND STAY AWAY FROM WINDOWS!

[Paul Sherman]

Seeing as it looks like it is going all a bit Linear, I am off to bed.

Cow camp looks likely to survive yet again for the 3rd time, going to hit that place early this year before the Weather takes another swipe at at those luuuveerly Cows on Plates!

Paul S

Edit: The Palo Pinto Storm has been Tornado Warned in the last few minutes and is heading hard east straight into DFW Metro for Evening Rush Hour!

Potty - Where are the Cams :blink: