Sunday, March 15, 2009

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 150452
SWODY1
SPC AC 150449

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1149 PM CDT SAT MAR 14 2009

VALID 151200Z - 161200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...

THE PERSISTENT SPLIT FLOW PATTERN WILL CONTINUE INTO SUNDAY. SERIES
OF IMPULSES WILL EJECT NEWD THROUGH BASE OF BROAD POSITIVELY TILTED
UPPER TROUGH INTO THE SERN STATES. COLD FRONT EXTENDING FROM A WEAK
SURFACE LOW OVER AL INTO THE NWRN GULF EARLY SUNDAY WILL ADVANCE
SLOWLY SEWD WHILE A WARM FRONT LIFTS NWD THROUGH SRN AND CNTRL GA.

...SERN STATES...

MOIST BOUNDARY LAYER WITH MID-UPPER 60S DEWPOINTS WILL PERSIST OVER
THE WRN AND CNTRL FL PANHANDLE INTO SERN AL AND SWRN GA. WIDESPREAD
RAIN WITH POTENTIAL FOR EMBEDDED LIGHTNING STRIKES WILL REMAIN OVER
MUCH OF THE SERN STATES WITHIN BROAD ZONE OF ISENTROPIC ASCENT
DOWNSTREAM FROM EJECTING SHORTWAVE TROUGH. THIS ACTIVITY WILL SHIFT
ENEWD DURING THE DAY. SOME BOUNDARY LAYER WARMING WILL BE POSSIBLE
ALONG SRN EXTENT OF THE RAIN AREA FROM SERN AL...SWRN GA AND THE FL
PANHANDLE. DESPITE INFLUX OF RICHER LOW LEVEL MOISTURE AND POTENTIAL
FOR SOME SURFACE HEATING...INSTABILITY IS EXPECTED TO REMAIN VERY
MARGINAL IN WARM SECTOR DUE TO WEAK MID-LEVEL LAPSE RATES WITH
MLCAPE BELOW 500 J/KG LIKELY.

A SWLY 40-50 KT LOW LEVEL JET FORECAST TO EXTEND FROM THE WRN FL
PANHANDLE THROUGH CNTRL AND NE GA EARLY SUNDAY WILL GRADUALLY SHIFT
NE AWAY FROM THE WARM SECTOR BY MID-LATE AFTERNOON IN ASSOCIATION
WITH THE EJECTING IMPULSE. HOWEVER...THIS FEATURE WILL ENHANCE LOW
LEVEL SHEAR OVER THE WARM SECTOR DURING THE FIRST HALF OF THE DAY
WITH FORECAST 0-1 KM STORM RELATIVE HELICITY ON THE ORDER OF 200-300
M2/S2 FROM THE FL PANHANDLE INTO SERN AL AND SW GA. WILL INTRODUCE A
CONDITIONAL 2% PROBABILITY FOR AN ISOLATED TORNADO...BUT AT THIS
TIME IT STILL APPEARS THE MARGINAL THERMODYNAMIC ENVIRONMENT WILL
REMAIN A LIMITING FACTOR FOR A MORE ROBUST SEVERE THREAT.

..DIAL/SMITH.. 03/15/2009

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