Sunday, November 25, 2007

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 251233
SWODY1
SPC AC 251230

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0630 AM CST SUN NOV 25 2007

VALID 251300Z - 261200Z

..THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE CENTRAL GULF
COAST...

..LOWER MS VALLEY AND CENTRAL GULF COAST STATES...
SLY LLJ WILL STRENGTHEN TODAY ACROSS THE LOWER MS VALLEY IN RESPONSE
TO APPROACHING UPPER TROUGH EJECTING SLOWLY NEWD ACROSS TX...WITH
ASSOCIATED SURFACE LOW NOW OFF THE SWRN LA COAST DEVELOPING NEWD
TOWARDS THE MID SOUTH THROUGH TONIGHT. THIS WILL ALLOW LOW LEVEL
MOISTURE TO RETURN NWD AHEAD OF APPROACHING COLD FRONT WITH SURFACE
DEWPOINTS IN THE 60S SPREADING INLAND ACROSS LA INTO CENTRAL MS AND
MUCH OF SWRN/WRN AL. HOWEVER...WEAK LAPSE RATES AND LIMITED SURFACE
HEATING WILL RESULT IN ONLY MARGINAL INSTABILITY ACROSS MUCH OF THE
SLIGHT RISK AREA. THE EXCEPTION WILL BE ACROSS SRN LA INTO FAR SRN
MS/SWRN AL/WRN FL PANHANDLE WHERE SURFACE DEWPOINTS IN THE UPPER 60S
SHOULD CONTRIBUTE TO AROUND 1000 J/KG MLCAPE.

TSTMS HAVE PERSISTED THROUGH MUCH OF THE NIGHT WITHIN PLUME OF DEEP
ASCENT FROM THE WRN GULF OF MEXICO INTO NERN TX. MUCH OF THIS
ACTIVITY NEAR AND INLAND FROM THE COAST WILL LIKELY REMAIN ELEVATED.
ALTHOUGH...THE POTENTIAL FOR SURFACE BASED TSTMS SHOULD INCREASE
THROUGH THE DAY AS THE WARM SECTOR EXPANDS N/NEWD AND MODEST SURFACE
HEATING OCCURS ACROSS MUCH OF SRN LA AND INTO PARTS OF SRN MS TO FAR
SWRN AL. DEEP LAYER ASCENT WILL INCREASE THE POTENTIAL FOR SEVERE
WEATHER INTO MONDAY MORNING SPREADING EWD ALONG AND AHEAD OF
EXPECTED PRE-FRONTAL CONVECTIVE BAND.

FORECAST SOUNDINGS WITHIN WARM SECTOR INDICATE THAT BOTH LOW-LEVEL
AND DEEP-LAYER SHEAR WILL INCREASE THROUGH THE PERIOD WITH KINEMATIC
ENVIRONMENT BECOMING INCREASINGLY SUPPORTIVE OF EMBEDDED BOW ECHOES
AND SUPERCELLS CAPABLE OF DAMAGING WINDS AND A FEW TORNADOES BY
LATER TODAY /ESPECIALLY AFTER DARK/. HOWEVER... FORECAST SOUNDINGS
INDICATE SURFACE-BASED INHIBITION WILL BECOME PROGRESSIVELY STRONGER
AWAY FROM THE COAST. GREATER TORNADO THREAT IS THEREFORE EXPECTED
TO BE GENERALLY ALONG AND JUST NORTH OF THE CENTRAL GULF COAST
REGION WHERE A MOIST...UNSTABLE BOUNDARY LAYER WILL COEXIST WITH
INCREASING LOW LEVEL SHEAR.

.EVANS/CROSBIE.. 11/25/2007

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