SPC AC 200043
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0743 PM CDT SAT AUG 19 2006
VALID 200100Z - 201200Z
...NO SVR TSTM AREAS FORECAST...
OZARK PLATEAU SUBTROPICAL HIGH CENTER IS IN THE PROCESS OF
WEAKENING. THIS IS IN RESPONSE TO THE SOUTHWARD ADVANCEMENT OF A
COOL/DRY INTRUSION THROUGH MUCH OF THE NORTH CENTRAL
U.S...ASSOCIATED WITH THE PROGRESSION OF SHORT WAVE TROUGHS EMBEDDED
WITHIN STRONGER WESTERLIES NEAR/NORTH OF THE CANADIAN/U.S. BORDER.
THE SURFACE COLD FRONT HAS ADVANCED INTO THE SOUTH CENTRAL
PLAINS/OZARK PLATEAU AND LOWER OHIO VALLEY...TO THE WEST SOUTHWEST
OF A DEEPENING SURFACE LOW OVER THE LOWER GREAT LAKES REGION. AS AN
UPSTREAM SOUTHERN BRANCH SHORT WAVE TROUGH DIGS ACROSS THE GREAT
LAKES REGION TONIGHT...THE SURFACE LOW IS FORECAST TO CONTINUE
DEEPENING AS IT MIGRATES TOWARD NEW ENGLAND. THIS WILL SUPPORT
FURTHER SOUTHWARD PROGRESSION OF THE COLD FRONT THROUGH THE OHIO
VALLEY TONIGHT. SOUTHWARD ADVANCEMENT OF FRONT SHOULD SLOW ACROSS
THE SOUTHERN PLAINS.
THE BULK OF THE ONGOING CONVECTIVE DEVELOPMENT IS OCCURRING IN A
MOISTURE PLUME...EMANATING FROM THE LOWER LATITUDE EASTERN
PACIFIC...AND ADVECTING AROUND THE WESTERN/NORTHERN PERIPHERY OF THE
SUBTROPICAL RIDGE. THE FRONTAL ZONE IS PROVIDING THE MAIN LOW-LEVEL
FOCUS FOR THIS ACTIVITY ACROSS THE SOUTHERN PLAINS AND PORTIONS OF
THE UPPER OHIO VALLEY...WITH OUTFLOW BOUNDARIES A FOCUS FROM THE
OZARK PLATEAU INTO THE LOWER OHIO VALLEY...AND HIGHER TERRAIN THE
GENERAL FOCUS ACROSS THE INTERMOUNTAIN WEST/ROCKIES. ADDITIONAL
STORMS HAVE DEVELOPED IN THE WARM FRONTAL ZONE ACROSS THE ST.
LAWRENCE VALLEY INTO NORTHERN NEW ENGLAND. DAYTIME HEATING SEEMS TO
BE PROVIDING A SIGNIFICANT FORCING FOR THESE STORMS...AND ONGOING
ACTIVITY IS EXPECTED TO DIMINISH CONSIDERABLY WITH THE ONSET OF
SURFACE COOLING THIS EVENING. THIS PROBABLY WILL BE SLOWEST TO
OCCUR ACROSS PARTS OF THE SOUTHERN ROCKIES AND SOUTH CENTRAL PLAINS.
...UPPER OHIO VALLEY INTO NORTHERN MID ATLANTIC COAST REGION...
SHEAR PROFILES IN WARM SECTOR OF DEVELOPING SURFACE CYCLONE ARE
MODERATE TO STRONG AND SUPPORTIVE OF SUPERCELLS. HOWEVER...CLOUD
COVER RESTRICTED SURFACE HEATING TODAY...AND WITH WEAK MID-LEVEL
LAPSE RATES...DESTABILIZATION HAS BEEN MINIMIZED DESPITE MOIST
LOW-LEVEL ENVIRONMENT. HOWEVER...FAVORABLE LARGE-SCALE FORCING
COULD STILL SUPPORT AN ISOLATED STRONG/SEVERE STORM THIS
EVENING...IN EVOLVING CLUSTER OF STORMS AHEAD OF COLD FRONT...AND TO
THE SOUTH OF RAIN COOLED AIR MASS TO THE LEE OF THE LOWER GREAT
LAKES...ACROSS PARTS CENTRAL/EASTERN PENNSYLVANIA INTO THE LOWER
HUDSON VALLEY.
...SOUTH CENTRAL PLAINS...
MODELS ARE SUGGESTIVE THAT A WEAK IMPULSE MIGRATING AROUND THE
SUBTROPICAL RIDGE COULD SUPPORT A CONSOLIDATION OF CONVECTIVE
DEVELOPMENT INTO A CLUSTER OF STORMS THAT PERSISTS WELL INTO THE
NIGHT ACROSS PARTS OF SOUTHERN KANSAS/NORTHERN OKLAHOMA. WEAK LOW
AND MID-LEVEL FLOW WILL MINIMIZE SEVERE POTENTIAL...BUT
THERMODYNAMIC PROFILES MAY REMAIN FAVORABLE FOR ISOLATED STRONG
GUSTY WINDS...PARTICULARLY NEAR HEAVIER PRECIPITATION CORES.
..KERR.. 08/20/2006
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0600Z
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