SWODY3
SPC AC 130726
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0226 AM CDT WED AUG 13 2008
VALID 151200Z - 161200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
PROGRESSIVE...MIDLEVEL TROUGH INITIALLY FROM QUEBEC SWWD INTO THE OH
VALLEY WILL TRANSLATE EWD THROUGH THE LOWER GREAT LAKES INTO NEW
ENGLAND BY SATURDAY MORNING. OVER THE CNTRL CONUS...AN UPPER LOW
WILL SLOWLY DRIFT SSWWD INTO THE CNTRL ROCKIES. IN THE LOW
LEVELS...COLD FRONT ATTENDANT TO THE NERN U.S. TROUGH WILL PUSH EWD
THROUGH THE MID ATLANTIC STATES INTO NEW ENGLAND. FARTHER W...A
COLD FRONT WILL CONTINUE SWD THROUGH THE SRN HIGH PLAINS WITH THE
NERN EXTENSION OF THIS BOUNDARY REMAINING MORE QUASI-STATIONARY OVER
THE CNTRL LOW PLAINS INTO LOWER MO VALLEY.
...SRN PLAINS...
LATEST MODEL GUIDANCE INDICATES NOTABLE DIFFERENCES IN: 1) THE
MOTION OF SURFACE COLD FRONT...2) THE DISTRIBUTION OF
INSTABILITY...AND 3) THE LOCATION OF MOST INTENSE TSTM DEVELOPMENT.
MOREOVER...THESE DATA SUGGEST THAT SEVERAL WEAKER PERTURBATIONS WILL
ROTATE THROUGH THE BASE OF THE LOW AND EWD ACROSS THE SRN PLAINS
FURTHER COMPLICATING THE SCENARIO.
IT DOES APPEAR THAT TSTMS WILL BECOME FOCUSED DURING THE AFTERNOON
ALONG AND IN THE WAKE OF THE SURFACE FRONT OVER ERN NM WHERE
LOW-LEVEL UPSLOPE FLOW WILL ENHANCE ASCENT. HERE...FORECAST
HODOGRAPHS INDICATE CONSIDERABLE VEERING OF WINDS WITH HEIGHT WITH
SUFFICIENT VERTICAL SHEAR FOR ORGANIZED/ROTATING UPDRAFTS.
ADDITIONAL STRONG STORMS WILL BE POSSIBLE THROUGH THE DIURNAL
HEATING CYCLE EWD/NEWD ALONG FRONTAL ZONE AND ANY RESIDUAL OUTFLOW
BOUNDARIES. WHILE LAPSE RATES WILL TEND TO WEAKEN WITH EWD
EXTENT...RICHER BOUNDARY LAYER MOISTURE WILL LARGELY CONTRIBUTE TO
SUFFICIENT INSTABILITY FOR ORGANIZED TSTM DEVELOPMENT. GIVEN THE
UNCERTAINTIES MENTIONED ABOVE...ONLY LOW PROBABILITIES WILL BE
INCLUDED IN THIS FORECAST.
...MID ATLANTIC COAST INTO SRN NEW ENGLAND...
MODEST BOUNDARY LAYER MOISTURE COUPLED WITH HEIGHT FALLS/DYNAMIC
COOLING ASSOCIATED WITH APPROACHING UPPER TROUGH WILL CONTRIBUTE TO
POCKETS OF MODERATE INSTABILITY FRIDAY AFTERNOON AHEAD OF COLD FRONT
AND PRE-FRONTAL TROUGH. THOUGH MID AND HIGH-LEVEL WIND FIELDS WILL
STRENGTHEN WITH THE ARRIVAL OF THE SHORT WAVE TROUGH...LOW-LEVEL
SHEAR IS FORECAST TO REMAIN RATHER WEAK. WHILE A FEW OF THE MORE
INTENSE STORMS WILL BE CAPABLE OF HAIL AND STRONG WIND GUSTS...THE
OVERALL SEVERE THREAT CURRENTLY APPEARS TOO MARGINAL FOR INCLUSION
OF A CATEGORICAL SLIGHT RISK.
..MEAD.. 08/13/2008
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