SPC AC 250702
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0202 AM CDT SUN OCT 25 2009
VALID 271200Z - 281200Z
...CNTRL GULF STATES TO LOWER OH VALLEY...
BOTH THE GFS AND ECMWF ARE IN REASONABLY GOOD AGREEMENT REGARDING
THE EVOLUTION OF A LONG WAVE TROUGH OVER THE WRN U.S. INTO THE MID
WEEK TIME FRAME. WITH HEIGHTS EXPECTED TO FALL DRAMATICALLY OVER
THE SWRN U.S. IT APPEARS THIS WILL ALLOW SHORTWAVE TROUGH OVER THE
LOWER MS VALLEY TO EJECT RAPIDLY NEWD IN A NEGATIVELY TILTED FASHION
ACROSS THE TN/OH VALLEY REGION. STRONG HEIGHT FALLS WILL COINCIDE
WITH A DEEPENING SFC LOW THAT SHOULD TRACK NNEWD ALONG THE MS DELTA
REGION FROM LA INTO SRN IND BY LATE AFTERNOON. FORECAST SHEAR
PROFILES ARE QUITE IMPRESSIVE AHEAD OF SURGING COLD FRONT WITH VERY
STRONG LOW LEVEL FLOW JUST OFF THE SFC...IN EXCESS OF 50-60KT WITHIN
A FEW THOUSAND FEET. NEEDLESS TO SAY...IF SUFFICIENT INSTABILITY
CAN DEVELOP WITHIN THE WARM SECTOR IT WOULD FAVOR THE POTENTIAL FOR
RELATIVELY LOW-TOPPED THUNDERSTORMS CAPABLE OF PRODUCING DAMAGING
WINDS. LATEST GUIDANCE SUGGEST A NARROW AXIS OF SFC DEW POINTS
APPROACHING 60F WILL SURGE AHEAD OF COLD FRONT PROVIDING JUST ENOUGH
INSTABILITY FOR AT LEAST A LINE OF ORGANIZED CONVECTION...POSSIBLY
LIGHTNING-FREE...AS LAPSE RATES WILL REMAIN SOMEWHAT MARGINAL.
GIVEN THE MARGINAL THERMODYNAMIC ENVIRONMENT WILL NOT OUTLOOK A
SLIGHT RISK AT THIS TIME...HOWEVER WILL INTRODUCE A 5% PROBABILITY
FOR A DAMAGING SQUALL LINE ALONG A STRONGLY FORCED...FAST MOVING
COLD FRONT.
..DARROW.. 10/25/2009
CLICK TO GET WUUS03 PTSDY3 PRODUCT
NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z
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