SWODY1
SPC AC 151957
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0257 PM CDT FRI JUN 15 2007
VALID 152000Z - 161200Z
..THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON AND EVENING OVER
PORTIONS OF THE CNTRL AND SRN APPALACHIANS...
..THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON AND EVENING OVER
PARTS OF SWRN TX...
..THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON AND TONIGHT OVER
PARTS OF THE NRN HIGH PLAINS...
..CNTRL/SRN APPALACHIANS...
TSTMS CONTINUE TO INCREASE IN COVERAGE THIS AFTERNOON AHEAD OF WEAK
SURFACE FRONT FROM PORTIONS OF FAR SRN KY AND WRN VA SWD THROUGH
PORTIONS OF MIDDLE AND ERN TN/WRN NC INTO THE GULF COAST STATES.
WHILE NOT OVERLY MOIST...AIR MASS ACROSS THE REGION HAS EXPERIENCED
RELATIVELY STRONG DIABATIC HEATING WHICH IS CONTRIBUTING TO MLCAPES
OF AROUND 1000 J/KG. IT APPEARS THAT LARGE-SCALE FORCING FOR ASCENT
ATTENDANT TO SHORT WAVE TROUGH DROPPING SWD THROUGH THE CNTRL
APPALACHIANS...IN CONJUNCTION WITH THE MODERATE INSTABILITY SHOULD
MAINTAIN ONGOING STORMS THROUGH THE REMAINDER OF THE AFTERNOON INTO
THIS EVENING.
REGIONAL VWPS INDICATE THAT VERTICAL SHEAR REMAINS QUITE
WEAK...WHICH SHOULD LIMIT UPDRAFT INTENSITY/ORGANIZATION.
HOWEVER...MARGINALLY SEVERE HAIL AND/OR LOCALLY STRONG WIND GUSTS
WILL REMAIN POSSIBLE WITH THE MOST INTENSE CELLS INTO THE EVENING
HOURS GIVEN THE MODERATE INSTABILITY.
..TX...
NOCTURNAL MCS AND ASSOCIATED COLD POOL CONTINUE SEWD THROUGH PARTS
OF SERN TX THIS AFTERNOON. HOWEVER...DOWNSTREAM AIR MASS OVER THE
MIDDLE AND UPPER TX COAST IS BEING OVERTURNED BY DIURNAL CONVECTION.
AS SUCH...IT APPEARS THAT ANY SEVERE THREAT WITH THIS SYSTEM WILL
REMAIN QUITE MARGINAL.
THOUGH THERE IS SOME UNCERTAINTY WITH REGARD TO CONVECTIVE
INITIATION...18Z MAF SOUNDING AND RUC OBJECTIVE FIELDS SUGGEST THAT
A POTENTIALLY MORE SUPPORTIVE ENVIRONMENT FOR ORGANIZED...SEVERE
STORMS EXISTS ALONG TRAILING PORTION OF NOCTURNAL MCS OUTFLOW
BOUNDARY OVER THE EDWARDS PLATEAU WWD INTO THE PERMIAN BASIN.
HERE...AIR MASS HAS BECOME MODERATELY UNSTABLE OWING TO STEEP
LOW/MID-LEVEL LAPSE RATES WITH MLCAPES OF 1000-1500 J/KG.
ADDITIONALLY...THESE DATA SHOW A BELT OF 30-35 KT NWLY MID-LEVEL
FLOW ACROSS REGION WHICH IS RESULTING IN SUFFICIENT DEEP LAYER SHEAR
FOR STORM ROTATION.
POSSIBLE MECHANISMS WHICH COULD HELP FOCUS TSTM DEVELOPMENT LATER
THIS AFTERNOON INTO EVENING ARE TERRAIN OVER SWRN TX...THE RESIDUAL
SURFACE BOUNDARIES AND INCREASING INFLUENCE OF SHORT WAVE TROUGH
TRANSLATING SWD TROUGH ERN NM/WRN TX. SHOULD STORMS DEVELOP AND
BECOME SUSTAINED...POTENTIAL WILL EXIST FOR A SUPERCELL OR TWO WITH
A THREAT OF LARGE HAIL AND DAMAGING WINDS.
..NRN PLAINS...
TSTMS ARE IN PROGRESS THIS AFTERNOON AHEAD OF SURFACE FRONT FROM THE
MN ARROWHEAD SWWD INTO ERN SD....WITHIN MODERATELY UNSTABLE AIR MASS
WITH MLCAPES OF 1000-1500 J/KG. VWP OBSERVATIONS AND WOOD LAKE MN
PROFILER SHOW THAT THE STRONGER MID AND HIGH-LEVEL WIND FIELDS
REMAIN CONFINED TO IMMEDIATE POST-FRONTAL AIR MASS OVER ND INTO NWRN
MN WITH SWLY WINDS OF 20-25 KT AT 500 MB OBSERVED ACROSS WARM
SECTOR. GIVEN THAT PRE-FRONTAL SURFACE WINDS ARE LIGHT AND
VEERED...VERTICAL SHEAR IS QUITE MARGINAL FOR STORM ORGANIZATION.
STILL...A FEW OF THE MORE INTENSE CELLS WILL BE CAPABLE OF
MARGINALLY SEVERE HAIL AND/OR LOCALLY DAMAGING WIND GUSTS THROUGH
THE EVENING HOURS.
FARTHER TO THE W...AIR MASS IS SLOWLY DESTABILIZING ALONG AND TO THE
N OF LOW-LEVEL FRONTAL ZONE FROM CNTRL SD INTO CNTRL WY DUE LARGELY
TO DIABATIC HEATING. THIS AREA WILL GENERALLY REMAIN BETWEEN
STRONGER SYNOPTIC SYSTEMS THROUGH TONIGHT...AND AS SUCH...LOW-LEVEL
WIND FIELDS REMAIN RELATIVELY WEAK. AREAS WHICH COULD POTENTIALLY
FOCUS CONVECTIVE DEVELOPMENT LATER THIS AFTERNOON INTO TONIGHT ARE:
1) FRONTAL BOUNDARY FROM BETWEEN PIR AND MBG WSWWD INTO SWRN SD...2)
THE BLACK HILLS...AND 3) PERHAPS THE BIG HORNS.
SHOULD STORMS DEVELOP...POTENTIAL WILL EXIST FOR ORGANIZED/ROTATING
UPDRAFTS CAPABLE OF LARGE HAIL AND STRONG WINDS GIVEN MLCAPES OF
500-1500 J/KG AND 40-50 KT OF EFFECTIVE BULK SHEAR.
.MEAD.. 06/15/2007
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