SPC AC 100600
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT MON AUG 10 2009
VALID 111200Z - 121200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE MID MS/TN/OH
VALLEYS...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE
NORTHEAST...
...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE CENTRAL
AND SRN HIGH PLAINS...
...SYNOPSIS...
THE MID-LEVEL TROUGH PROGRESSING EWD ACROSS THE ERN HALF OF THE
CONUS SHOULD EXPAND/AMPLIFY WITH TIME...DOWNSTREAM OF A SECOND
TROUGH MAKING SOME EWD PROGRESS ACROSS THE PAC NW/WRN CANADA.
AT THE SURFACE...A COLD FRONT IS PROGGED TO MOVE INLAND/ACROSS THE
NWRN CONUS. A SECOND FRONT STRETCHING FROM NRN NEW ENGLAND WSWWD
ACROSS THE MIDWEST/OH VALLEY INTO OK/THE TX PANHANDLE/NM EARLY IS
PROGGED TO SHIFT SEWD ACROSS THE NORTHEAST...AND MORE SLOWLY SWD
ACROSS THE OH/TN VALLEYS AND SRN PLAINS THROUGH THE PERIOD.
...MID MS/TN/OH VALLEY REGION...
DAYTIME HEATING WILL LIKELY CONTRIBUTE TO MODERATE DESTABILIZATION
ACROSS THE MID MS/TN/OH VALLEYS...INVOF A SURFACE COLD FRONT
PROGRESSING VERY SLOWLY SWD ACROSS THIS REGION. STORMS SHOULD
BECOME WIDESPREAD BY MID AFTERNOON...AIDED BY DESTABILIZING AIRMASS
AND A PRONOUNCED MID-LEVEL SHORT-WAVE TROUGH SHIFTING ESEWD ACROSS
THE AREA.
DEEP-LAYER FLOW WILL NOT BE PARTICULARLY STRONG /H5 WNWLYS IN THE 25
TO 35 KT RANGE ALONG THE IMMEDIATE FRONTAL ZONE DURING THE AFTERNOON
AND DECREASING WITH SWD EXTENT/. HOWEVER...SHEAR/INSTABILITY
COMBINATION SHOULD SUPPORT SOME ORGANIZED/MULTICELL CLUSTERS CAPABLE
OF PRODUCING HAIL AND LOCALLY-DAMAGING WINDS. STORMS/SEVERE
POTENTIAL SHOULD BEGIN TO DIMINISH SLOWLY THROUGH THE EVENING IN
CONJUNCTION WITH DIURNAL STABILIZATION OF THE LOW-LEVEL AIRMASS.
...ERN PA/NJ/SERN NY/SRN NEW ENGLAND...
SCATTERED SHOWERS AND THUNDERSTORMS SHOULD BE ONGOING AT THE START
OF THE PERIOD ACROSS THE SLIGHT RISK AREA...AHEAD OF A MID-LEVEL
SHORT-WAVE TROUGH CROSSING THE LOWER GREAT LAKES/SRN ONTARIO/SWRN
QUEBEC. WHILE UNCERTAINTY WITH RESPECT TO THE DEGREE OF ONGOING
PRECIPITATION/CLOUD COVER LEADS TO QUESTIONS REGARDING
DESTABILIZATION POTENTIAL...ATTM EXPECT AT LEAST MARGINAL
INSTABILITY TO DEVELOP BY EARLY AFTERNOON -- WHICH WILL SUPPORT
ADDITIONAL STORM DEVELOPMENT AND/OR REINTENSIFICATION OF ONGOING
CONVECTION. MODERATE/WLY DEEP-LAYER WIND FIELD WILL SUPPORT
FAST-MOVING STORM CLUSTERS/LINES...WITH DAMAGING WINDS LIKELY TO BE
THE PRIMARY SEVERE THREAT. THE THREAT AREA IS EXPECTED TO SHIFT EWD
WITH TIME...LIKELY DIMINISHING/MOVING OFFSHORE THROUGH EARLY
EVENING.
...PARTS OF THE CENTRAL/SRN HIGH PLAINS...
POST-FRONTAL ESELY UPSLOPE FLOW INTO NERN NM/SERN CO COMBINED WITH
AFTERNOON HEATING/DESTABILIZATION WILL LIKELY YIELD STORM
DEVELOPMENT ACROSS THIS REGION. DEVELOPMENT MAY BE AIDED BY A
SUBTLE MID-LEVEL SHORT-WAVE TROUGH PROGGED BY BOTH THE NAM AND GFS
TO SHIFT SEWD INTO THE HIGH PLAINS WITHIN NWLYS ON THE NRN PERIPHERY
OF THE RIDGE CENTERED OVER AZ/NM.
WITH MID-LEVEL FLOW FORECAST NEAR 25 KT FROM THE NW/WNW ATOP
LOW-LEVEL SELYS...SHEAR WILL SUPPORT ORGANIZED/ROTATING STORMS.
THUS...HAIL/WIND POTENTIAL APPEARS TO WARRANT INCLUSION OF A SLIGHT
RISK/15% THREAT AREA ATTM. STORMS/ISOLATED SEVERE POTENTIAL SHOULD
SPREAD OFF THE HIGHER PLAINS INTO SWRN KS AND THE TX/OK PANHANDLES
THROUGH THE EVENING...AS A WEAK SELY LOW-LEVEL JET DEVELOPS.
..GOSS.. 08/10/2009
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
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