SWODY1
SPC AC 221223
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0723 AM CDT FRI MAY 22 2009
VALID 221300Z - 231200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
A BENIGN PATTERN IN TERMS OF ORGANIZED SEVERE STORM POTENTIAL WILL
PERSIST OVER THE CONUS FOR THE NEXT SEVERAL DAYS. ALOFT...THE
PRIMARY BELT OF WESTERLIES IS CONFINED TO THE CANADIAN BORDER...WITH
RELATIVELY WEAK MID-UPPER FLOW OVER THE MAJORITY OF THE CONUS.
MEANWHILE...THERE ARE TWO PRIMARY MOISTURE PLUMES AND ASSOCIATED
REGIONS OF DEEP CONVECTION -- ONE ACROSS FL AND THE NE GULF COAST
WITH THE SUBTROPICAL CYCLONE S OF THE FL PANHANDLE...AND ANOTHER
OVER THE FOUR CORNERS REGION TO THE N/NE OF A MID LEVEL LOW NEAR THE
AZ/MEXICO BORDER. MID LEVEL LAPSE RATES WILL REMAIN RATHER POOR
/ROUGHLY MOIST ADIABATIC/ WITHIN THE MOISTURE PLUME ACROSS THE FOUR
CORNERS REGION...WHICH WILL LIMIT THE MAGNITUDE OF INSTABILITY AND
THE POTENTIAL FOR DOWNBURST-PRODUCING STORMS. ACROSS THE NE GULF
COAST...THE BELT OF SOMEWHAT STRONGER ELY LOW-LEVEL FLOW AND
MARGINAL VERTICAL SHEAR WILL BE LOCATED ACROSS THE FL PANHANDLE TO
THE NE OF THE GULF LOW. HOWEVER...LAPSE RATES WILL BE POOR AND THE
RICHER BOUNDARY LAYER MOISTURE AND GREATER INSTABILITY WILL BE
REMOVED TO THE S OF THIS SOMEWHAT STRONGER FLOW.
...N CENTRAL HIGH PLAINS THIS AFTERNOON...
A NARROW ZONE OF OVERLAP BETWEEN THE SRN FRINGE OF THE MID-UPPER
WESTERLIES AND THE STEEPER LAPSE RATES ORIGINATING OVER NV/ID MAY
DEVELOP THIS AFTERNOON IN THE BLACK HILLS REGION FROM WRN SD INTO NE
WY. HERE...THE COMBINATION OF AFTERNOON TEMPERATURES IN THE LOW 70S
WITH MID 40S BOUNDARY LAYER DEWPOINTS WILL SUPPORT MLCAPE VALUES
NEAR 500 J/KG...IN AN ENVIRONMENT WITH STRAIGHT HODOGRAPHS AND 0-6
KM BULK SHEAR OF 30-40 KT. THE COMBINATION OF VERTICAL SHEAR AND
BUOYANCY MAY BE SUFFICIENT FOR STORMS WITH SUPERCELL STRUCTURES IN
THE AREA OF UPSLOPE EASTERLY/NORTHEASTERLY FLOW ALONG THE COLD
FRONT. THE STRONGEST STORMS COULD PRODUCE MARGINALLY SEVERE
HAIL/GUSTY OUTFLOW WINDS...BUT WEAK INSTABILITY WILL LIMIT THE
OVERALL SEVERE THREAT.
..THOMPSON/SMITH.. 05/22/2009
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