DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 131214
SWODY1
SPC AC 131212

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0712 AM CDT SAT APR 13 2013

VALID 131300Z - 141200Z

...NO SVR TSTM AREAS FORECAST...

...SE LA COAST...
AN UPPER-LEVEL TROUGH WILL MOVE EWD ACROSS NRN MEXICO TODAY
APPROACHING THE TX GULF COAST TONIGHT. AHEAD OF THE UPPER-LEVEL
TROUGH...MOISTURE ADVECTION WILL TAKE PLACE ACROSS THE TX AND LA
GULF COASTS AS A LOW-LEVEL JET BECOMES FOCUSED OVER THE WRN GULF OF
MEXICO. MODEL FORECASTS DEVELOP AN AREA OF THUNDERSTORM ACTIVITY
ABOUT 200 STATUTE MILES SOUTH OF THE LA COAST AS THE LOW-LEVEL JET
BEGINS TO DEVELOP LATE THIS EVENING. THIS CONVECTION EXPANDS IN
COVERAGE AND MOVES TOWARD THE LA COAST AFTER MIDNIGHT. BY LATE IN
THE PERIOD...IT APPEARS A CLUSTER OF THUNDERSTORMS WILL MOVE INTO
COASTAL SECTIONS OF SRN LA.

FORECAST SOUNDINGS LATE TONIGHT NEAR THE LA COAST SOUTHWEST OF NEW
ORLEANS GRADUALLY MOISTEN LOW-LEVELS AS SFC DEWPOINTS INCREASE INTO
THE LOWER TO MID 60S F. IN ADDITION...FORECAST SOUNDINGS ALONG THE
LA COAST AFTER 06Z/SUN INCREASE 0-6 KM SHEAR INTO THE 50 TO 60 KT
RANGE AND 0-1 KM SHEAR TO AROUND 25 KT AS THE LOW-LEVEL JET
APPROACHES THE LA COAST. THESE FACTORS ALONG WITH LCL HEIGHTS BELOW
1000 METERS AGL MAY BE ENOUGH FOR A MARGINAL TORNADO THREAT WITH
CELLS THAT CAN OBTAIN ROTATION AND MOVE INLAND FROM THE GULF OF
MEXICO. STRONG WIND GUSTS WILL ALSO BE POSSIBLE WITH THE MORE
INTENSE DISCRETE CELLS. THE CENTER OF THE LOW-LEVEL JET IS FORECAST
TO STILL BE SOUTH OF THE LA COAST AT 12Z/SUN SUGGESTING THE
STRONGEST LOW-LEVEL SHEAR WILL STILL BE OFFSHORE. FOR THIS
REASON...WILL KEEP THE TORNADO AND WIND DAMAGE PROBABILITIES AT 2
PERCENT AND 5 PERCENT RESPECTIVELY.

..BROYLES/GARNER.. 04/13/2013

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