Tuesday, October 11, 2011

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 111629
SWODY1
SPC AC 111627

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1127 AM CDT TUE OCT 11 2011

VALID 111630Z - 121200Z

...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON AND EVENING OVER
WRN PARTS OF TX/OK...

...CNTRL/SRN PLAINS...

HEIGHT FALLS ASSOCIATED WITH EXIT REGION OF INTENSE UPPER-LEVEL JET
STREAK PROPAGATING FROM THE PACIFIC NW AND CNTRL ROCKIES INTO THE
CNTRL/SRN PLAINS WILL CONTRIBUTE TO AMPLIFICATION OF LARGE-SCALE
TROUGH OVER THE CNTRL CONUS THIS PERIOD. IN THE LOW LEVELS...LEE
TROUGH OVER THE HIGH PLAINS WILL INTENSIFY TODAY AND GRADUALLY
TRANSITION TO A PACIFIC FRONT WHILE PROGRESSING EWD INTO LOWER
ELEVATIONS OF THE GREAT PLAINS.

STEEPENING LOW- TO MIDLEVEL LAPSE RATES WILL COINCIDE WITH A
MOISTENING BOUNDARY LAYER TO SUPPORT AIR MASS DESTABILIZATION TODAY
E OF LEE TROUGH/PACIFIC FRONT. INCREASING HIGH CLOUDS SPREADING EWD
FROM THE ROCKIES MAY TEMPER DAYTIME HEATING AND THE DESTABILIZATION
PROCESS...BUT AFTERNOON MLCAPE VALUES WILL STILL APPROACH 500-1000
J/KG ACROSS THE WARM SECTOR.

WATER VAPOR IMAGERY AND MODEL DIAGNOSTIC FIELDS INDICATE A LEAD
SHORT-WAVE TROUGH OVER ERN PARTS OF CO/NM WHICH WILL CONTINUE EWD.
EXTRAPOLATION OF CURRENT MOTION SUGGESTS THAT THE STRONGER FORCING
FOR ASCENT WILL LIKELY SHIFT E OF THE SURFACE TROUGH/FRONT PRIOR TO
PEAK HEATING. NONETHELESS...THE TRAILING INFLUENCE OF THIS FEATURE
WILL COMBINE WITH LOW-LEVEL ASCENT ALONG INTENSIFYING SURFACE
BOUNDARY TO FOSTER ISOLATED TO WIDELY SCATTERED TSTMS LATER THIS
AFTERNOON INTO EVENING. WHILE ISOLATED SEVERE STORMS CAPABLE OF
HAIL AND GUSTY WIND WILL BE POSSIBLE ALONG THE LENGTH OF THE LEE
TROUGH/PACIFIC FRONT...THE GREATEST POTENTIAL FOR ORGANIZED STORM
MODES --INCLUDING SUPERCELLS-- APPEARS TO BE OVER PARTS OF THE TX/OK
PNHDLS INTO NWRN TX AND WRN OK. HERE...THE EXIT REGION OF MID- AND
HIGH-LEVEL JET STREAKS WILL ENHANCE DEEP-LAYER SHEAR WITHIN A
KINEMATIC ENVIRONMENT EXHIBITING VERTICALLY VEERING WINDS WITH
HEIGHT. LARGE HAIL APPEARS TO BE THE PRIMARY HAZARD...THOUGH
LOCALLY DAMAGING WIND GUSTS WILL BE POSSIBLE...ESPECIALLY AS STORMS
DEVELOP A COLD POOL.

...FAR ERN NC...

WEAK SURFACE LOW OFF THE SC COAST WILL CONTINUE TO DEVELOP NWD ALONG
COASTAL BOUNDARY THIS PERIOD...POTENTIALLY ALLOWING A NARROW AXIS OF
HIGHER THETA-E AIR TO OVERSPREAD THE IMMEDIATE COAST AND THE OUTER
BANKS. SHOULD THIS OCCUR...ISALLOBARICALLY BACKED NEAR-SURFACE FLOW
--AND RESULTANT ENHANCEMENT OF LOW-LEVEL SHEAR-- WILL SUPPORT THE
POTENTIAL FOR BRIEF SUPERCELL STRUCTURES WITH A LOW PROBABILITY RISK
FOR A TORNADO.

..MEAD/ROGERS.. 10/11/2011

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