SPC 1730Z Day 2 Outlook
DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1230 PM CDT THU APR 26 2012 VALID 271200Z - 281200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS CENTRAL/ERN KS...FAR NRN/NERN OK INTO WRN/CENTRAL MO... ...SYNOPSIS... MODELS ARE IN GENERAL AGREEMENT THROUGH 36 HOURS /28/00Z/ WITH THE TRACK AND EVOLUTION OF THE COMPACT SRN CA SHORTWAVE TROUGH AS IT MOVES FROM THE CENTRAL/SRN HIGH PLAINS TO THE LOWER AND MID MO VALLEY BY EARLY FRI EVENING. BEYOND 28/00Z...MODELS DIFFER WITH THE DEGREE THAT THIS SYSTEM DEAMPLIFIES FRI NIGHT AS IT TRACKS TOWARD THE UPPER MS VALLEY. MEANWHILE...A BLOCKING PATTERN WILL PERSIST ACROSS THE NRN TIER OF THE U.S. AND CANADA AS THE SRN EXTENT OF A PACIFIC TROUGH FORMS INTO A CLOSED LOW OVER THE NRN ROCKIES/HIGH PLAINS AND A DEEPENING LOW DEVELOPS FROM NRN NEW ENGLAND INTO ERN CANADA. AT 12Z FRI...A TRAILING COLD ATTENDANT TO THE NEW ENGLAND/ERN CANADA LOW IS EXPECTED TO EXTEND FROM OFF THE MID ATLANTIC COAST INTO NC...AND WWD INTO NRN AL...MS INTO AR. MEANWHILE...THE WRN EXTENT OF THIS SAME BOUNDARY WILL BE MOVING NWD LATE DAY 1 ACROSS OK AND THE TX PANHANDLE TO SWRN KS AS A WARM FRONT. MODELS GENERALLY AGREE THAT A SURFACE LOW PRESSURE INVOF THE SERN CO/SWRN KS BORDER...WILL SHIFT EWD ACROSS KS WITH SOME FURTHER DEEPENING THROUGH 28/00Z...THEN WEAKEN FRI NIGHT...REACHING NERN MO BY 12Z SAT. THE ATTENDANT WARM FRONT WILL CONCURRENTLY ADVANCE NEWD ACROSS CENTRAL/ERN KS INTO MO...TN...AND SHOULD EXTEND INTO THE LOWER OH VALLEY BY LATE IN THE FORECAST PERIOD. ...CENTRAL/ERN KS...NRN OK...FAR NWRN AR...MO AND MID MS VALLEY... SURFACE BASED TSTMS...SOME POTENTIALLY SEVERE WITH AN ATTENDANT THREAT FOR A FEW TORNADOES...SHOULD BE ONGOING AT THE START OF D2 ACROSS SWRN INTO CENTRAL KS IN VICINITY AND ESE OF THE SURFACE LOW MOVING INTO WRN KS AND THE SEWD EXTENT OF THE WARM FRONT. /REFER TO D1 CONVECTIVE OUTLOOK/. THE RESPONSE IN THE MASS FIELDS IMMEDIATELY DOWNSTREAM OF THE EJECTING COMPACT SHORTWAVE TROUGH ARE EXPECTED TO MAINTAIN THERMODYNAMIC ADJUSTMENTS ACROSS CENTRAL INTO ERN KS FRI MORNING AND AFTERNOON AS THE WARM FRONT/WARM SECTOR SPREAD ENEWD. ALTHOUGH THE INITIAL SELY LOW LEVEL JET ACROSS OK/KS WILL VEER THROUGH THE DAY...HEIGHT FALLS WITH THE SYSTEM WILL SUSTAIN STRONG LLJ WIND SPEEDS ENHANCING LOW LEVEL SHEAR WITHIN THE DESTABILIZING WARM SECTOR AS IT EXPANDS NEWD. A STRONGER CAP EXTENDING SWD OVER OK CONTINUES TO LIMIT THE OVERALL SEVERE WEATHER THREAT WITH SRN EXTENT...WHILE THE COMPACT NATURE OF THE SRN CA TROUGH MAY RESULT IN A FOCUSED AREA OF GREATER SEVERE WEATHER COVERAGE ACROSS CENTRAL/ERN KS AND POTENTIALLY INTO WRN MO. THIS HIGHER THREAT AREA SHOULD BE CONFINED TO THE TRACK OF THE SURFACE LOW/TRIPLE POINT. HOWEVER... GIVEN REMAINING UNCERTAINTY IN THE TRACK OF THIS LATTER FEATURE... THIS OUTLOOK WILL MAINTAIN 15 PERCENT PROBABILITIES WITH THE POTENTIAL FOR HIGHER PROBABILITIES INTRODUCED IN LATER OUTLOOKS. THE THREAT FOR SUPERCELLS/ORGANIZED STORMS WILL SPREAD INTO WRN/CENTRAL MO BY LATE FRI AFTERNOON/EVENING AS THE TROUGH AND SURFACE FEATURES ADVANCE ENEWD. MODERATE INSTABILITY AND STRONG EFFECTIVE BULK SHEAR WILL MAINTAIN THE SEVERE WEATHER THREAT WITH EWD EXTENT...WITH THIS OUTLOOK EXTENDING THE SLIGHT RISK FARTHER EWD INTO MORE OF CENTRAL AND NWRN MO. ....SC/NRN GA/NERN AL/SRN MIDDLE AND SERN TN... THE NC PORTION OF THE COLD FRONT WILL SHIFT SWD AND STALL ACROSS SC ON FRI...WHILE THE NRN AL/MS PORTION MOVES NWD AS A WARM FRONT. A WEAK MIDLEVEL IMPULSE IS EXPECTED TO ADVANCE ESEWD ACROSS THIS REGION SUPPORTING TSTM DEVELOPMENT AS SURFACE INHIBITION IS WEAKENED BY LATE MORNING/EARLY AFTERNOON GIVEN SURFACE HEATING. EFFECTIVE BULK SHEAR OF 25-30 KT SUGGESTS MULTICELLS WILL BE POSSIBLE...WITH THE REMNANTS OF THE EML /7-7.5 C PER KM MIDLEVEL LAPSE RATES/ SUPPORTING AN ISOLATED HAIL THREAT. ..PETERS.. 04/26/2012
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day2otlk_1730.html
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