SWODY1
SPC AC 111214
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0714 AM CDT MON OCT 11 2010
VALID 111300Z - 121200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE ARKLATEX INTO CNTRL
TX...
...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF PA AND NJ...
...CNTRL PLAINS/OZARK PLATEAU SWD INTO CNTRL/ERN TX AND WRN LA...
SOME REMNANT OF NOCTURNAL MCS ONGOING OVER NERN TX WILL LIKELY BE
MAINTAINED OVER THE ARKLATEX TODAY...FORCED BY A VORTICITY MAXIMUM
ROTATING AROUND PARENT DEEP-LAYER CYCLONE SHIFTING SEWD TOWARD THE
OZARK PLATEAU REGION. WHILE SWLY LLJ WILL UNDERGO DIURNAL WEAKENING
THIS MORNING...MODEST INFLOW SHOULD PERSIST... ENCOURAGING
BACKBUILDING/PREFERENTIAL STORM DEVELOPMENT ALONG THE SRN/SWRN FLANK
OF SYSTEM. CURRENTLY OBSERVED DEW POINTS OF 60-65 F WITHIN
PRE-FRONTAL WARM SECTOR OVER CNTRL/ERN TX MAY DECREASE LATER TODAY
WITH THE ONSET OF DEEPER PBL MIXING. HOWEVER... DAYTIME HEATING AND
PRESENCE OF STEEP MIDLEVEL LAPSE RATES /REF. 12Z DRT SOUNDING/
SHOULD SUPPORT MLCAPE VALUES APPROACHING 1000-2000 J/KG BY MID/LATE
AFTERNOON.
THE DESTABILIZING AIR MASS COUPLED WITH THE SUSTAINED LOW-LEVEL
CONVERGENCE ALONG SYNOPTIC FRONT AND RESIDUAL CONVECTIVE
OUTFLOW...AND INCREASING INFLUENCE OF MID/UPPER-LOW APPROACHING THE
REGION SHOULD ALL CONTRIBUTE TO THE DEVELOPMENT AND/OR
INTENSIFICATION OF STORMS BY AFTERNOON ACROSS SLIGHT RISK AREA.
WHILE DEEP-LAYER VERTICAL SHEAR WILL REMAIN SOMEWHAT MARGINAL /I.E.
25-35 KT/ OWING TO THE WEAKENING OF THE SYNOPTIC SYSTEM AND VEERED
SURFACE FLOW...THE DEGREE OF INSTABILITY WILL BE SUPPORTIVE OF
ORGANIZED STORMS AND/OR STORM CLUSTERS CAPABLE OF HAIL AND LOCALLY
DAMAGING WIND GUSTS THROUGH THIS EVENING.
ELSEWHERE...ISOLATED OCCURRENCES OF MAINLY SMALL HAIL WILL BE
POSSIBLE THIS AFTERNOON INTO EVENING FROM CNTRL KS SEWD THROUGH ERN
OK/WRN AR INVOF MIDLEVEL COLD POOL ASSOCIATED WITH UPPER LOW.
...PA/NJ...
MORNING WATER VAPOR IMAGERY SHOWS AN INTENSIFYING SHORT WAVE TROUGH
RAPIDLY TRANSLATING SEWD THROUGH ONTARIO WHICH SHOULD CONTINUE SEWD
THROUGH THE GREAT LAKES REGION BY TUESDAY MORNING. IN THE LOW
LEVELS...A WEAK FRONT SITUATED ALONG THE LOWER GREAT LAKES WILL
SLOWLY SAG SEWD...PROVIDING THE FOCUS FOR STRONG TO POTENTIALLY
SEVERE STORM DEVELOPMENT LATER THIS AFTERNOON INTO TONIGHT.
CURRENT SATELLITE-DERIVED PW IMAGERY AND 12Z OBSERVED SOUNDING DATA
INDICATE THAT PRE-FRONTAL AIR MASS IS NOT OVERLY MOIST.
HOWEVER...INCREASED DIABATIC WARMING IN THE BOUNDARY LAYER COUPLED
WITH 500 MB TEMPERATURES COOLING TO -16 TO -17 C WILL CONTRIBUTE TO
STEEPENING LAPSE RATES WITH AFTERNOON MLCAPE VALUES APPROACHING
500-1000 J/KG WITH A DECREASING CAP. LATEST MESOSCALE AND
CONVECTION-RESOLVING MODEL GUIDANCE ARE IN GENERALLY GOOD AGREEMENT
IN SUGGESTING THAT SURFACE-BASED STORM DEVELOPMENT WILL BECOME
INCREASINGLY LIKELY BY 11/21Z ALONG THE COLD FRONT OVER WRN AND
CNTRL PARTS OF PA. STORMS SHOULD INCREASE IN COVERAGE THROUGH THE
REMAINDER OF THE AFTERNOON INTO TONIGHT WHILE MOVING/DEVELOPING EWD
TO OFF THE NJ COAST.
VERTICAL SHEAR WILL STRENGTHEN THROUGH THE DAY IN ADVANCE OF THE
ABOVE-MENTIONED SHORT WAVE TROUGH WITH FORECAST HODOGRAPHS
INDICATING 35-40 KT OF DEEP WLY SHEAR PRIOR TO ANTICIPATED STORM
INITIATION. GIVEN THE STEEPENING LAPSE RATES AND STRENGTHENING
SHEAR...SETUP WILL BE SUPPORTIVE OF ORGANIZED STORM DEVELOPMENT WITH
AN ASSOCIATED THREAT FOR DAMAGING WIND GUSTS AND HAIL CONTINUING
INTO TONIGHT.
..MEAD/BOTHWELL.. 10/11/2010
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