SWODY1
SPC AC 210056
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0756 PM CDT SUN MAY 20 2007
VALID 210100Z - 211200Z
..THERE IS A SLGT RISK OF SVR TSTMS TONIGHT OVER PORTIONS OF THE
NRN HIGH PLAINS AND WRN DAKOTAS...
..THERE IS A SLGT RISK OF SVR TSTMS THROUGH THE REMAINDER OF THE
EVENING OVER SWRN TX...
..NRN HIGH PLAINS INTO WRN DAKOTAS...
LATEST MESOANALYSIS INDICATED PRIMARY SURFACE LOW OVER N-CNTRL WY
WITH ATTENDANT SURFACE BOUNDARY EXTENDING EWD FROM THIS FEATURE TO
SECONDARY SURFACE LOW OVER CNTRL SD. THE LOW-LEVEL BAROCLINIC ZONE
THEN STRETCHED EWD THROUGH E-CNTRL SD AND THEN MORE SEWD ACROSS NRN
IA INTO CNTRL IL. THE GREATEST AIR MASS DESTABILIZATION HAS
OCCURRED OVER CNTRL/ERN SD ALONG AND S OF SURFACE FRONT WHERE STRONG
DIABATIC HEATING COUPLED WITH DEWPOINTS IN THE MID 50S TO LOWER 60S
HAVE CONTRIBUTED TO MLCAPES OF 1500-2500 J/KG. GENERALLY COOLER
TEMPERATURES AND A DRIER BOUNDARY LAYER HAVE TEMPERED DEGREE OF
DESTABILIZATION WWD THROUGH NRN WY INTO ERN/CNTRL MT...THOUGH RUC
OBJECTIVE FIELDS SUGGEST THAT POCKETS OF MODERATE INSTABILITY
/MLCAPES OF 1000-1500 J PER KG/ DO EXIST ON IMMEDIATE COOL SIDE OF
FRONTAL ZONE.
DESPITE THE MARGINAL THERMODYNAMIC CONDITIONS ACROSS MT...WATER
VAPOR IMAGERY INDICATES A WELL-DEFINED SHORT WAVE TROUGH LIFTING
NEWD THROUGH WRN MT...PERHAPS SUPPORTING THE CONVECTIVE DEVELOPMENT
INVOF 3HT AS OF 0015Z. A FURTHER INCREASE IN STORM COVERAGE WILL
LIKELY OCCUR THIS EVENING AND OVERNIGHT FROM VICINITY OF SURFACE
BOUNDARY OVER NRN WY NWD/NEWD ACROSS ERN MT AS LARGE-SCALE FORCING
FOR ASCENT ATTENDANT TO THIS SHORT WAVE TROUGH OVERSPREADS
INSTABILITY AXIS. SUFFICIENT DEEP LAYER VERTICAL SHEAR IS IN PLACE
TO SUPPORT SUPERCELLS AND/OR BOWING STRUCTURES CAPABLE OF MAINLY
DAMAGING WINDS AND LARGE HAIL. THIS SEVERE THREAT WILL LIKELY
CONTINUE EWD INTO NWRN SD AND WRN ND OVERNIGHT.
A SEPARATE AREA OF STRONG TO SEVERE TSTMS HAS DEVELOPED OVER WRN SD
THIS AFTERNOON AND EARLY EVENING FROM NE OF PHP TO NE OF CDR WITHIN
STEEP LAPSE RATE AND MODERATELY UNSTABLE ENVIRONMENT. WHILE DEEP
LAYER VERTICAL SHEAR IS NOT PARTICULARLY STRONG...CURRENT MERRIMAN
NEB PROFILER INDICATES MODEST MID AND HIGH LEVEL WLY FLOW WITH 30-35
KT OF BULK SHEAR THROUGH THE LOWEST 6 KM AGL.
EXPECT THIS MCS TO LIKELY CONTINUE THROUGH THE REMAINDER OF THE
EVENING OVER PORTIONS OF S-CNTRL SD...PERHAPS INTO NWRN NEB. LARGE
HAIL AND DAMAGING WIND GUSTS WILL REMAIN THE PRIMARY SEVERE WEATHER
THREATS.
..SWRN TX...
CLUSTER OF STRONG/SEVERE STORMS CONTINUES TO EVOLVE THIS EVENING
OVER PORTIONS OF CULBERSON...REEVES AND JEFF DAVIS COUNTIES...WITH
ADDITIONAL STORMS SWD INTO THE BIG BEND AREA.
AMBIENT ENVIRONMENT CHARACTERIZED BY MODERATE INSTABILITY /MLCAPES
OF AROUND 1000 J/KG AND 30-35 KT OF EFFECTIVE BULK SHEAR/ IS
EXPECTED TO REMAIN SUPPORTIVE OF ORGANIZED/ROTATING STORMS FOR THE
NEXT FEW HOURS WITH THE PRIMARY THREAT BEING LARGE HAIL. THIS
THREAT SHOULD DECREASE AFTER 03-04Z AS BOUNDARY LAYER COOLS AND
SLOWLY STABILIZES...AND STORMS MOVE TOWARD PROGRESSIVELY MORE CAPPED
ENVIRONMENT NEAR AND E OF THE PECOS RIVER /REF 21/00Z DRT SOUNDING/.
.MEAD.. 05/21/2007
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