SPC AC 221247
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0647 AM CST MON NOV 22 2010
VALID 221300Z - 231200Z
...NO SVR TSTM AREAS FORECAST...
A LARGE LOW AMPLITUDE UPPER TROUGH WILL PROGRESS RAPIDLY EASTWARD
ACROSS THE CENTRAL UNITED STATES TODAY...WHILE THE ASSOCIATED 80-90
KNOT MID LEVEL JET NOSES INTO THE GREAT LAKES REGION. STRONG
SOUTHWESTERLY LOW LEVEL WINDS AHEAD OF THE TROUGH HAVE BEEN
TRANSPORTING PARTIALLY MODIFIED GULF AIR MASS NORTHWARD WITH
DEWPOINTS IN THE UPPER 50S AS FAR NORTH AS PORTIONS OF IL/IND. AS A
COLD FRONT SAGS SOUTHWARD INTO THE MID MS VALLEY AND GREAT LAKES
THIS EVENING AND TONIGHT...THE POTENTIAL FOR ISOLATED STRONG/SEVERE
STORMS WILL INCREASE.
OPERATIONAL AND STORM-SCALE MODEL GUIDANCE IS IN FAIR AGREEMENT THAT
SCATTERED THUNDERSTORMS WILL AFFECT PORTIONS OF IL/WI/IND/LOWER MI
THIS MORNING THROUGH THE AFTERNOON...IN REGION OF STRONG LOW LEVEL
WARM ADVECTION. 12Z OBSERVED AND FORECAST SOUNDINGS SUGGEST RATHER
STEEP MID LEVEL LAPSE RATES BUT WEAK CAPE AND MINIMAL SURFACE-BASED
INSTABILITY. SMALL HAIL WILL BE POSSIBLE WITH THE STRONGEST
CELLS...BUT ORGANIZED SEVERE STORMS ARE NOT ANTICIPATED.
BY LATE AFTERNOON...THE PRIMARY COLD FRONT WILL EXTEND FROM A
SURFACE LOW OVER SOUTHERN WI INTO CENTRAL MO AND NORTHERN OK.
SCATTERED THUNDERSTORMS WILL BEGIN TO DEVELOP ALONG THE FRONT AND
SPREAD SOUTHEASTWARD ACROSS IL/IND. THERMODYNAMIC PARAMETERS WILL
REMAIN QUITE WEAK. HOWEVER...STRONG LOW/MID LEVEL WIND FIELDS AND
LINEAR NATURE OF CONVECTION WILL POSE A RISK OF GUSTY AND
OCCASIONALLY SEVERE WIND GUSTS. UNCERTAINTY REMAINS REGARDING
WHETHER SUFFICIENT INSTABILITY WILL DEVELOP FOR ORGANIZED SEVERE
STORMS...SO WILL MAINTAIN ONLY 5% PROBS AT THIS TIME.
THUNDERSTORMS WILL DEVELOP SOUTHWARD ALONG THE FRONT DURING THE
EVENING INTO PARTS OF AR. LOW LEVEL MOISTURE AND INSTABILITY WILL
BE SLIGHTLY STRONGER IN THIS AREA...BUT VEERED LOW LEVEL WINDS AND
WEAKER LARGE SCALE FORCING WILL BE OFFSETTING FACTORS FOR A MORE
ROBUST SEVERE THREAT.
..HART/HURLBUT.. 11/22/2010
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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