DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 070600
SWODY2
SPC AC 070558

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1258 AM CDT TUE OCT 07 2008

VALID 081200Z - 091200Z

...NO SVR TSTM AREAS FORECAST...

...SERN STATES...

COLD ADVECTION AND MID LEVEL JET DROPPING SWD ALONG WRN PERIPHERY OF
UPPER TROUGH OVER THE CNTRL/SRN PLAINS WILL CONTRIBUTE TO SOME SWD
AMPLIFICATION AS THIS FEATURE MOVES TOWARD THE SERN STATES ON
WEDNESDAY. MODELS DIFFER ON EVOLUTION OF THE TROUGH WITH THE GFS AND
ECMWF BEING MORE PROGRESSIVE AND FARTHER NORTH THAN THE NAM AND NAM
KF WHICH CLOSE OFF THIS FEATURE EARLIER. THE UPPER TROUGH WILL BE
ACCOMPANIED BY A COLD FRONT. A WARM FRONT MAY LIFT SLOWLY NWD INTO
THE SRN PARTS OF THE GULF COASTAL STATES.

SURFACE HIGH PRESSURE OVER THE ERN U.S. WILL SHIFT EAST WITH SELY
FLOW BECOMING ESTABLISHED EAST OF COLD FRONT THAT WILL ACCOMPANY THE
UPPER TROUGH. BOUNDARY LAYER DEWPOINTS WILL RANGE FROM NEAR 70 OVER
THE CNTRL GULF COASTAL AREA TO LOW 60S OVER THE TN VALLEY. IT STILL
APPEARS THAT WIDESPREAD CLOUDS AND ONGOING CONVECTION WITHIN ZONE OF
ASCENT ATTENDING UPPER TROUGH WILL LIMIT DESTABILIZATION AND LAPSE
RATES OVER MUCH OF THE MOIST AXIS. MCLAPE WILL SHOULD REMAIN AOB 500
J/KG OVER MOST OF THE REGION. HOWEVER...MODERATE INSTABILITY WILL BE
POSSIBLE MAINLY OVER SRN PARTS OF THE GULF COASTAL STATES WHERE LOW
CLOUDS ARE MORE LIKELY TO MIX OUT AND WHERE RICHER MOISTURE WILL
RESIDE SOUTH OF WARM FRONT. ESELY LOW LEVEL TRAJECTORIES FROM
SURFACE RIDGE OVER THE ATLANTIC AND POTENTIAL FOR ONGOING
PRECIPITATION ON COOLER SIDE OF WARM FRONT SHOULD LIMIT NWD RETREAT
OF THIS BOUNDARY.

BEST CHANCE FOR A FEW STRONG TO SEVERE STORMS WILL PROBABLY REMAIN
SOUTH OF WARM FRONT OVER SRN PARTS OF THE GULF COASTAL STATES WHERE
GREATER DESTABILIZATION POTENTIAL WILL EXIST. LOW LEVEL WINDS WILL
WEAKEN DURING THE DAY AS THE LOW LEVEL JET SHIFTS NWD THROUGH THE
SRN AND CNTRL APPALACHIANS. HOWEVER...MODERATE WSWLY 500 MB FLOW
ALONG SRN PERIPHERY OF UPPER TROUGH WILL MAINTAIN SUFFICIENT BULK
SHEAR FOR A THREAT OF ROTATING UPDRAFTS. LARGER HODOGRAPHS WILL
EXIST NORTH OF WARM FRONT AND MAY BE SUFFICIENT FOR A THREAT OF
LOW-LEVEL MESOCYCLONES AS STORMS CROSS THIS BOUNDARY. HOWEVER...ANY
TORNADO THREAT CURRENTLY APPEARS TOO CONDITIONAL GIVEN PROBABILITY
THAT THE BOUNDARY LAYER MAY REMAIN TOO STABLE ON THE COOLER SIDE OF
THIS FRONT.

MODEL DIFFERENCES WITH UPPER LOW TIMING AND PLACEMENT AS WELL AS
UNCERTAINTIES REGARDING EVOLUTION OF EARLY CONVECTION PRECLUDES MORE
THAN 5% SEVERE PROBABILITIES AT THIS TIME. HOWEVER...THIS AREA WILL
CONTINUE TO BE MONITORED FOR A POSSIBLE SLIGHT RISK IN LATER
OUTLOOKS.

..DIAL.. 10/07/2008

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