DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 171239
SWODY1
SPC AC 171237

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0737 AM CDT MON SEP 17 2012

VALID 171300Z - 181200Z

...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON THROUGH TONIGHT
ACROSS PARTS OF THE GULF COAST REGION...

...GULF COAST REGION...
WATER VAPOR LOOPS SHOW TWO UPPER TROUGHS AFFECTING THE
CENTRAL/EASTERN UNITED STATES. THE FIRST SYSTEM IS OVER EAST
TX...AND WILL TRACK EASTWARD INTO THE GULF COAST REGION THROUGH THE
FORECAST PERIOD. MODEL GUIDANCE INDICATES THE ASSOCIATED SURFACE
LOW /CURRENTLY OFF THE MIDDLE TX COAST/ WILL MOVE ACROSS THE LA
DELTA AND INTO SOUTHERN MS/AL OVERNIGHT. STRENGTHENING LOW/MID
LEVEL WIND FIELDS IN THE WARM SECTOR OF THIS LOW WILL RESULT IN
INCREASINGLY FAVORABLE VERTICAL SHEAR FOR ORGANIZED/ROTATING
CONVECTION. DESPITE NEAR MOIST-ADIABATIC LAPSE RATES...SURFACE
DEWPOINTS IN THE 70S WILL YIELD MARGINAL INSTABILITY AND THE
POTENTIAL FOR SURFACE-BASED STORMS. AT THIS TIME...THE GREATEST
RISK OF SEVERE WEATHER WILL LIKELY OCCUR AFTER DARK. LOCALLY
DAMAGING WINDS AND A TORNADO OR TWO ARE POSSIBLE ACROSS THE SLIGHT
RISK AREA.

...UPPER MIDWEST...
THE SECOND UPPER TROUGH IS CURRENTLY OVER THE DAKOTAS...AND IS
FORECAST TO ROTATE SOUTHEASTWARD INTO THE UPPER MS VALLEY BY
TOMORROW MORNING. A RATHER STRONG COLD FRONT WILL SURGE SOUTHWARD
ACROSS PARTS OF IA/WI/MO/IL/IND THIS AFTERNOON AND EVENING.
RELATIVELY STRONG HEATING AHEAD OF THE FRONT...COUPLED WITH
DEWPOINTS IN THE 50S AND SUBSTANTIAL FRONTAL CONVERGENCE IS LIKELY
TO RESULT IN SCATTERED SHOWERS AND THUNDERSTORMS. THE STRONGEST OF
THESE STORMS COULD PRODUCE HAIL AND GUSTY WINDS. ORGANIZED SEVERE
STORMS ARE NOT EXPECTED AT THIS TIME.

..HART/LEITMAN.. 09/17/2012

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