ZCZC SPCSWODY1 ALL
ACUS01 KWNS 121228
SPC AC 121227

STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK 
DAY 1 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWE46 KWNS.

VALID 121300Z - 131200Z

NO SVR TSTM AREAS FCST.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 75 SSW GDP
40 WNW ROW 15 NNE LVS 30 SSW LHX 30 NW LAA 35 SSE AKO 25 N AKO
40 WNW BFF 25 SE CPR 55 SSW TWF 70 NE SVE 25 SSW LMT 30 W RDM
35 S YKM 15 NW EPH 25 NNE 4OM ...CONT... 65 NE HVR 25 WSW GGW
10 W DIK 30 SSW ABR 30 SSW YKN 20 NNE LNK 10 NE TOP 30 S CNU
35 SSE PGO 25 WSW POE 25 SSW LCH.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 15 SSE MIA
15 NNW SRQ ...CONT... 25 S TLH 10 SE VLD 20 SSE SSI.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 10 E PSM EEN
40 W ALB 30 SSE SYR 10 NE ROC.

STRONG GENERALLY ZONAL UPPER JET WILL CONTINUE TO PROPAGATE SLOWLY
EASTWARD ACROSS THE NORTHERN PACIFIC...TO THE SOUTH OF A BROAD
POLAR LOW CENTERED IN THE VICINITY OF SOUTHWESTERN ALASKA.  MODELS
SUGGEST SHORT WAVE TROUGH EMBEDDED WITHIN JET WILL MIGRATE EAST OF
THE ALEUTIANS INTO THE NORTHEAST PACIFIC DURING THIS FORECAST
PERIOD.  AS THIS OCCURS...DOWNSTREAM TROUGH WILL SHIFT OUT OF THE
PACIFIC NORTHWEST INTO THE NORTHERN ROCKIES...WHILE CLOSED LOW/MID-
LEVEL CYCLONE MOVES EAST OF THE GREAT LAKES...INTO NEW ENGLAND BY
13/12Z.

BECOMING CUT-OFF FROM MAIN BELT OF WESTERLIES TO THE NORTH...A
CLOSED LOW WILL CONTINUE TO SLOWLY DIG OFF THE CALIFORNIA COAST.  
DOWNSTREAM OF THIS FEATURE...LOW AMPLITUDE ANTICYCLONIC FLOW WILL
PREVAIL NORTH OF SUBTROPICAL RIDGE...FROM CALIFORNIA INTO THE
PLAINS THROUGH MUCH OF THE DAY.  HOWEVER...NOCTURNAL STRENGTHENING
OF LOW-LEVEL JET EAST OF SURFACE TROUGH IN THE LEE OF THE ROCKIES
WILL CONTRIBUTE TO SOME SHARPENING OF SHORT WAVE RIDGE THROUGH THE
HIGH PLAINS BY THE END OF THIS FORECAST PERIOD.

GIVEN RATHER BENIGN LARGE-SCALE PATTERN...STABILIZATION IN WAKE OF
STRONG SURFACE CYCLOGENESIS OVER THE UPPER MIDWEST...AND ASSOCIATED
FRONTAL PASSAGE THROUGH THE CENTRAL/EASTERN STATES...IS EXPECTED TO
MINIMIZE CONVECTIVE THREAT ACROSS MUCH OF THE NATION TODAY/TONIGHT.

...SOUTHERN HIGH PLAINS...
MODELS SUGGEST RETURN FLOW OF LOW-LEVEL MOISTURE FROM THE RIO
GRANDE VALLEY INTO THE SOUTHERN HIGH PLAINS...IN CONJUNCTION WITH
STRONG DAYTIME HEATING ACROSS THE HIGHER TERRAIN...WILL CONTRIBUTE
TO DESTABILIZATION FROM THE BIG BEND AREA OF TEXAS NORTHWARD
THROUGH PARTS OF WEST TEXAS/EASTERN NEW MEXICO.  MEAN MIXED LAYER
CAPE ON THE ORDER OF 1000 J/KG APPEARS POSSIBLE...BUT FORCING FOR
CONVECTIVE DEVELOPMENT APPEARS MOSTLY LIMITED TO OROGRAPHY.  THUS
...WHILE VEERING OF WIND FIELDS WITH HEIGHT MAY CONTRIBUTE TO
MODERATE VERTICAL SHEAR SUPPORTIVE OF AT LEAST BRIEF UPDRAFT
ROTATION...ENHANCING POTENTIAL FOR MARGINALLY SEVERE HAIL/GUSTS IN
STRONGEST CELLS...THESE STORMS ARE EXPECTED TO BE RELATIVELY
ISOLATED.

SOMEWHAT BETTER CONVECTIVE POTENTIAL WILL DEVELOP FARTHER TO THE
NORTH...ACROSS THE TEXAS PANHANDLE/WESTERN OKLAHOMA TONIGHT. MODELS
SUGGEST WEAK MID-LEVEL SHORT WAVE TROUGH WILL MIGRATE INTO THIS
REGION...CONTRIBUTING TO STRENGTHENING LOW-LEVEL JET AND ASSOCIATED
WARM ADVECTION REGIME ACROSS THE PLAINS BY LATE EVENING.  OVERNIGHT
...ALL MODELS SUGGEST DIVERGENT UPPER FLOW FIELD BECOMES FOCUSED
ACROSS THE SOUTH CENTRAL HIGH PLAINS...IN RIGHT ENTRANCE REGION OF
HIGH LEVEL JET...ON NORTHEASTERN PERIPHERY OF SHORT WAVE RIDGE. 
GIVEN INFLUX OF MOISTURE SUPPORTIVE OF WEAK TO MODERATE INSTABILITY
ABOVE SURFACE INVERSION...FORCING FOR UPWARD VERTICAL MOTION MAY
SUPPORT SMALL CLUSTER OF STORMS...WITH ISOLATED MARGINALLY SEVERE
HAIL POSSIBLE IN STRONGEST CELLS.

...NORTHERN ROCKIES/HIGH PLAINS...
STRONG DAYTIME HEATING ALONG/IN THE LEE OF THE NORTHERN ROCKIES...
ACROSS THE HIGH PLAINS OF MONTANA...WILL CONTRIBUTE TO STEEPENING
LAPSE RATES AS SHORT WAVE TROUGH APPROACHES LATE THIS AFTERNOON.
LOW/MID-LEVEL ENVIRONMENT WILL REMAIN QUITE DRY...HOWEVER...WHICH
SHOULD MINIMIZE AREAL COVERAGE/INTENSITY OF THUNDERSTORM ACTIVITY.

...FLORIDA...
MODELS SUGGEST SLIGHT AMPLIFICATION AND EASTWARD PROGRESSION OF
EASTERN U.S. TROUGH WILL WEAKEN MID-LEVEL CONVECTION INHIBITION
ACROSS THE FLORIDA PENINSULA TODAY.  THIS MAY BE ENOUGH FOR AT
LEAST SCATTERED THUNDERSTORM ACTIVITY NEAR/SHORTLY AFTER PEAK
HEATING...MAINLY WHERE LOW-LEVEL CONVERGENCE BECOMES FOCUSED ALONG
SEA BREEZE VICINITY OF THE ATLANTIC COAST.
 
..KERR.. 05/12/03

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