SWODY1
SPC AC 141250
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0750 AM CDT FRI SEP 14 2007
VALID 141300Z - 151200Z
..NO SVR TSTM AREAS FORECAST...
..SYNOPSIS...
FAST MOVING AND RELATIVELY DEEP TROUGH WILL SWEEP EWD FROM THE UPPER
MIDWEST INTO NY/PA DURING THE PERIOD. THIS WILL DRIVE A COLD
FRONT...CURRENTLY STRETCHING FROM THE ERN GREAT LAKES SWWD INTO THE
SRN PLAINS...SWD AND EWD TO THE ATLANTIC AND GULF COASTAL REGIONS BY
SATURDAY MORNING.
HUMBERTO/S REMNANT SURFACE LOW PRESSURE WAS LOCATED IN ERN MS NEAR
CBM AT 12Z AND SHOULD MOVE THROUGH NRN AL/GA TODAY AND INTO WRN NC
BY EVENING.
..OH/WRN NY/PA/ERN LOWER MI...
A BAND OF ELEVATED THUNDERSTORMS WAS CO-LOCATED WITH THE FRONT
ACROSS LOWER MI THIS MORNING...WITHIN ZONE OF STRONG HEIGHT
FALLS/UVV. ALTHOUGH SOME MID/HIGH CLOUDS FROM HUMBERTO/S REMNANTS
WILL MOVE ACROSS THE AREA THIS MORNING...INCREASING WLY FLOW ALOFT
SHOULD HELP PUSH CLOUDS EWD...ALLOWING DIURNAL HEATING. ALTHOUGH
SURFACE DEWPOINTS ARE ONLY EXPECTED TO CLIMB INTO THE UPPER 50S...
TEMPERATURES IN THE MID 70S WOULD YIELD MLCAPES AROUND 500 J/KG.
DESPITE THE MARGINAL INSTABILITY...THE STRONGLY PACKED ISOTHERMS AND
20-30 KT WNWLY WINDS AT 850 MB...SHOULD SUPPORT THE DEVELOPMENT OF A
FAST MOVING THUNDERSTORM LINE DEVELOPING ALONG THE FRONT BETWEEN
18Z-21Z ACROSS NRN OH. THIS LINE SHOULD MOVE EWD INTO WRN PA/NY BY
EARLY EVENING...WITH ISOLATED STRONG WIND GUSTS POSSIBLE. ANY WIND
THREAT SHOULD DIMINISH AS THE STORMS MOVE EWD INTO CENTRAL
NY/PA...WHERE HEATING IS EXPECTED TO BE SOMEWHAT RESTRICTED DUE TO
CLOUDS SPREADING IN FROM THE SOUTHWEST.
..NERN NM/SERN CO/WRN KS ...
UPSLOPE FLOW...ON THE BACK SIDE OF THE LARGE SURFACE HIGH OVER THE
MO RIVER VALLEY REGION...WILL ENHANCE THE ASCENT ALONG THE EAST
SLOPES OF THE ROCKIES. THIS MAY BE SUFFICIENT FOR ISOLATED STORMS TO
DEVELOP LATE THIS AFTERNOON ALONG THE HIGHER TERRAIN. THE SHEAR MAY
BE SUPPORTIVE OF SOME MID LEVEL ROTATION/SEVERE THREAT... THOUGH
STORM COVERAGE IS EXPECTED TO BE TOO ISOLATED FOR A SLIGHT RISK.
OVERNIGHT...STRENGTHENING LOW LEVEL JET SHOULD AID IN THE
DEVELOPMENT OF ELEVATED STORMS...ROOTED AROUND 750 MB...TO DEVELOP
OVER WRN KS. ALTHOUGH HAIL IS POSSIBLE WITH THESE STORMS... MARGINAL
INSTABILITY AND WEAK SHEAR ABOVE 750 MB SHOULD INHIBIT A MORE
WIDESPREAD SEVERE THREAT.
..NRN AL ENEWD INTO WRN NC...
SURFACE LOW PRESSURE WAS NEAR CBM...WITH A WEAK BOUNDARY/WARM FRONT
EXTENDING EWD ACROSS NRN AL AND THEN NEWD TO NEAR THE TN/NC BORDER.
UPPER MIDWEST TROUGH SHOULD STRENGTHEN THE FLOW ALOFT ACROSS THE SRN
STATES...WITH SURFACE LOW PRESSURE EXPECTED TO ACCELERATE ALONG THE
WARM FRONT...AND INTO WRN NC BY EVENING. BHM 12Z SOUNDING SHOWS THAT
THE SHEAR PROFILES HAVE REMAINED STRONG NEAR THE LOW PRESSURE
SYSTEM...POSSIBLY DUE TO FEEDBACK FROM CONVECTION LOCATED NEAR THE
CENTER. THE SEVERE THREAT HAS REMAINED LOW SINCE THUNDERSTORMS HAVE
BEEN EMBEDDED WITHIN A CLUSTER OF RAIN...WITH LITTLE EVIDENCE OF
STRONGER UPDRAFTS. IF WARMING CAN OCCUR JUST AHEAD OF THE LOW AND
ALONG THE WARM FRONT...AN ISOLATED TORNADO/WIND EVENT WOULD BE
POSSIBLE. HOWEVER...ATTM IT APPEARS THE ENEWD TRACK OF THE LOW WOULD
KEEP THE STRONGER SHEAR NORTH OF ANY APPRECIABLE WARMING...SO THE
THREAT FOR A TORNADO OR WIND DAMAGE APPEARS SLIM.
.IMY/GUYER.. 09/14/2007
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