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Severe Weather Thread November 7-8


David Reimer

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SWODY2....30% and hatched.

DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1255 AM CDT SUN NOV 06 2011

VALID 071200Z - 081200Z

..THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE SRN PLAINS

..SRN AND CNTRL PLAINS

A FAIRLY POTENT LOOKING UPPER-LEVEL TROUGH WILL MOVE ACROSS THE

DESERT SOUTHWEST MONDAY AS A 60 TO 75 KT MID-LEVEL JET EJECTS NEWD

INTO THE GREAT PLAINS. WELL TO THE EAST OF THE TROUGH...A SFC LOW

WILL DEVELOP ACROSS WEST TX DURING THE DAY AS LOW-LEVEL SLY FLOW

INCREASES ACROSS THE SRN PLAINS. STRONG MOISTURE ADVECTION WILL

BRING SFC DEWPOINTS INTO THE LOWER 60S F ACROSS NORTH TX INTO CNTRL

OK WHERE SCATTERED THUNDERSTORMS MAY BE ONGOING MONDAY MORNING INTO

THE AFTERNOON IN THE REGION OF STRONG WARM ADVECTION. THE CONVECTIVE

COVERAGE SHOULD BE GREATEST ALONG THE AXIS OF THE LOW-LEVEL JET FROM

THE TX HILL COUNTRY NWD ACROSS NW TX INTO WCNTRL OK. FURTHER TO THE

WEST OF THE MIDDAY STORMS ON THE WRN EDGE OF THE LOW-LEVEL JET...THE

MODELS FORECAST MODERATE DESTABILIZATION WITH SBCAPE VALUES POSSIBLY

REACHING THE 1000 TO 1500 J/K RANGE BY LATE AFTERNOON. DUE TO THE

INSTABILITY AND STRONG LARGE-SCALE ASCENT MOVING OUT INTO THE SRN

PLAINS...DISCRETE CELL INITIATION SHOULD TAKE PLACE DURING THE EARLY

AFTERNOON WITH A RAPID INCREASE IN CONVECTIVE COVERAGE. ALTHOUGH THE

MODELS ALL DEVELOP STORMS...THE GFS IS MUCH MORE AGGRESSIVE

CONCERNING CONVECTIVE COVERAGE AND THIS SOLUTION SEEMS REASONABLE.

AT THIS POINT...IT APPEARS A SQUALL-LINE WILL DEVELOP IN WRN OK AND

NW TX AND MOVE EWD INTO WCNTRL OK AND ACROSS NORTH TX SIMILAR TO THE

GFS SOLUTION.

FORECAST SOUNDINGS ACROSS WCNTRL OK AND NORTHWEST TX ON TUESDAY

GRADUALLY INCREASE DEEP LAYER SHEAR PROFILES AS THE EXIT REGION OF

THE MID-LEVEL JET MOVES OUT INTO THE SRN PLAINS. WITH 0-6 KM SHEAR

VALUES AS HIGH AS 50 KT COMBINED WITH SUBSTANTIAL VEERING WITH

HEIGHT FROM THE SFC TO 850 MB SHOULD EASILY SUPPORT AN ORGANIZED

SEVERE THREAT. THE MAIN QUESTION IS STORM MODE. THE CURRENT THINKING

IS THAT SUPERCELLS MAY DEVELOP EARLY IN THE EVENT WITH A FAIRLY

QUICK TRANSITION TO A LINEAR STRUCTURED MCS. THE EXCEPTION MAY BE ON

THE SRN END OF THE LINE FROM NORTHWEST SWD INTO WCNTRL TX WHERE MORE

DISCRETE CONVECTION MAY PERSIST INTO THE EARLY EVENING. THIS SHOULD

RESULT IN A LONGER-LIVED SUPERCELL THREAT FROM FAR SW OK SWD TO

AROUND SAN ANGELO WITH SEVERAL TORNADOES AND POSSIBLY LARGE HAIL

GREATER THAN 2 INCHES IN DIAMETER WHERE A HATCHED AREA FOR

SIGNIFICANT HAIL HAS BEEN ADDED. A STRONG TORNADO ALSO CAN NOT BE

RULED OUT. ALTHOUGH LARGE HAIL AND AN ISOLATED TORNADO THREAT MAY

ALSO EXIST FURTHER NORTH INTO CNTRL OK...THE MORE PREDOMINANT THREAT

COULD BECOME WIND DAMAGE AS A SQUALL-LINE MOVES EWD INTO ECNTRL OK

AND ACROSS NORTH TX DURING THE EARLY EVENING.

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Whoa pretty large 30 area...welcome back to standard time everyone :thumbsup:

Impressive environment with very strongly backed surface winds, 50-60 kts of 0-6 km shear, 150-300 m2/s2 0-3 km SRH (100-200 m2/s2 0-1 km SRH) and 1500-2000+ J/kg CAPE at 00z in that general area being forecast by the 06z NAM.

Pretty damn robust STP in the area as per the 06z run...

post-6489-0-18392500-1320572378.gif

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New Day 2, 30%/hatched area expanded a bit towards FWD. 40 STI areas also appear to have expanded at 21z and 00z as per the most recent runs of the SREF:

post-6489-0-03533300-1320601793.gif

DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1130 AM CST SUN NOV 06 2011

VALID 071200Z - 081200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE SOUTHERN PLAINS...

...SYNOPSIS...

WITH THE POLAR JET/SHORTWAVE TROUGH CURRENTLY AMPLIFYING/DIGGING

SOUTH-SOUTHEASTWARD ALONG THE CA COAST...THIS SHORTWAVE TROUGH IS

EXPECTED TO TURN MORE EAST/EVENTUALLY NORTHEASTWARD THROUGH MONDAY

NIGHT AS IT TAKES ON A MORE NEUTRAL TILT WHILE CROSSING THE SOUTHERN

ROCKIES. IN RESPONSE...SURFACE CYCLOGENESIS WILL OCCUR ACROSS THE

SOUTHERN HIGH PLAINS...WITH AN INCREASINGLY MOIST AIRMASS TO THE

EAST OF A SHARPENING WEST TX DRYLINE...AND TO THE SOUTH OF

SOUTHWEST-NORTHEAST ORIENTED FRONTAL ZONE EXTENDING FROM THE

SOUTH-CENTRAL PLAINS TO THE MIDWEST/MIDDLE MS VALLEY. THIS SCENARIO

WILL SET THE STAGE FOR A POTENTIALLY ACTIVE SEVERE WEATHER DAY ON

MONDAY /AND INTO TUESDAY/ ACROSS THE SOUTH-CENTRAL CONUS.

...CENTRAL/SOUTHERN PLAINS TO OZARKS/ARKLATEX...

GIVEN THE LARGE SCALE SCENARIO AS DESCRIBED...SCATTERED TSTMS ARE

LIKELY TO BE ONGOING/INCREASE EARLY IN THE PERIOD WITHIN A WARM

ADVECTION/ISENTROPIC LIFT REGIME...AND THIS INCLUDES THE POSSIBILITY

OF ELEVATED STRONG/SEVERE TSTMS MAINLY CAPABLE OF HAIL ACROSS

NORTHWEST TX INTO OK MONDAY MORNING. WITH TIME...GIVEN THE ARRIVAL

OF DEEP FORCING FOR ASCENT AND A CONTINUALLY MOISTENING/DIURNALLY

WARMING BOUNDARY LAYER...CONDITIONS WILL BECOME MORE FAVORABLE INTO

THE AFTERNOON/EARLY EVENING HOURS FOR SURFACE BASED SEVERE TSTM

DEVELOPMENT...ESPECIALLY TO THE IMMEDIATE EAST OF THE GRADUALLY

DEEPENING SURFACE LOW/PERIPHERAL DRYLINE ACROSS NORTHWEST/PARTS OF

NORTH-CENTRAL TX INTO SOUTHWEST OK. HERE...SURFACE DEWPOINTS IN THE

LOWER/PERHAPS MIDDLE 60S F WILL BE PREVALENT BENEATH AN

EASTWARD-ADVECTING ELEVATED MIXED LAYER...WHICH SHOULD ALLOW FOR

MLCAPES TO REACH AS HIGH AS 1000-1500 J/KG BY AFTERNOON.

WHILE THE SPECIFIC DETAILS OF CONVECTIVE MODE ARE A BIT

UNCERTAIN...A MIXED MODE SEEMS PROBABLE WITHIN A HIGHLY SHEARED

ENVIRONMENT. THIS INCLUDES THE POSSIBILITY OF INITIAL MODE

SUPERCELLS ESPECIALLY ACROSS NORTHWEST/PARTS OF NORTH-CENTRAL TX TO

SOUTHWEST OK...ASIDE FROM A GENERAL TENDENCY FOR LINEAR/SQUALL

LINE-TYPE DEVELOPMENT MONDAY NIGHT ACROSS MUCH OF OK AND WEST/NORTH

TX...ESPECIALLY AS THE COLD FRONT BEGINS TO ACCELERATE EASTWARD LATE

MONDAY NIGHT/EARLY TUESDAY. OVERALL...ALL FACETS OF SEVERE WEATHER

WILL BE POSSIBLE...INCLUDING LARGE HAIL...DAMAGING WINDS...AND

TORNADOES...INCLUDING RISKS FOR A STRONG TORNADO GIVEN THE

INCREASINGLY LARGE/ELONGATED HODOGRAPHS THAT ARE EXPECTED ACROSS THE

WARM SECTOR BY MONDAY AFTERNOON/NIGHT.

..GUYER.. 11/06/2011

post-6489-0-46259800-1320602223.gif

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SREF popping a 50%

12z/18z NAM forecast soundings for CDS-FDR-F05 looking increasingly ominous, with better thermodynamic profiles than previous runs (SBCAPE ~2500 J/kg, LI -6) and large looping hodographs by 00z.

post-972-0-04936800-1320613911.gif

This is definitely shaping up as the most significant threat Texas/Oklahoma have seen in the fall/winter months since back on February 10, 2009.

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Actually, I expect a ton of chasers to be out. It sounds like folks are flying down from your area. When you get a good setup in November in good terrain, everyone and their donkey chases it.

Not to mention that this could be one of the last threats of the season in prime chase country...yeah...I would expect a lot of chasers.

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This is definitely shaping up as the most significant threat Texas/Oklahoma have seen in the fall/winter months since back on February 10, 2009.

I'll post a more detailed analysis later, but the way I see it, it's probably the biggest threat the area from SPS up to Childress has seen in probably many years.

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My thoughts on tomorrow's severe weather event across Texas. This was written so the general public could understand it and it's pretty much just a overview of what everyone here already knows. Still, if you're interested, you can read it at http://texasstormchasers.com/2011/11/05/severe-weather-expected-on-monday/

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I'll post a more detailed analysis later, but the way I see it, it's probably the biggest threat the area from SPS up to Childress has seen in probably many years.

I agree, I don't remember chasing a tornadic supercell out towards Wichita Falls and I've been chasing since 2008. Tomorrow could be a doozy and I'm looking forward to it. I'll be out chasing along with half the state.

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It is funny because what partially makes this event unique is the very fact it is November...you never see such a deep wave with respectable cross barrier terrain flow forcing compensating upslope flow combined with a fall like wave off the EC contributing to those impressive trajectories in the low levels.

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I agree, I don't remember chasing a tornadic supercell out towards Wichita Falls and I've been chasing since 2008. Tomorrow could be a doozy and I'm looking forward to it. I'll be out chasing along with half the state.

the only good supercell I've seen that was really close to produce was down around FDR on 4/26/09.

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