SWODY1
SPC AC 131247
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0647 AM CST TUE DEC 13 2011
VALID 131300Z - 141200Z
...NO SVR TSTM AREAS FORECAST...
A LARGE UPPER LOW OFF THE COAST OF SOUTHERN CA WILL WEAKEN AND MOVE
SLOWLY EASTWARD INTO THE SOUTHWEST STATES TODAY...WHILE WEAK UPPER
RIDGING OCCURS OVER THE CENTRAL/EASTERN STATES. A STRONG MID/UPPER
LEVEL JET MAX CURRENTLY OFF THE NORTHERN MEXICAN COAST WILL ROTATE
INLAND ACROSS NORTHERN MEXICO...AND INTO THE SOUTHERN ROCKIES AND
CENTRAL PLAINS TONIGHT. LARGE SCALE FORCING FOR ASCENT WILL
INTENSIFY ALONG THE JET AXIS ACROSS THE DESERT SOUTHWEST AND INTO
THE CENTRAL PLAINS DURING THIS FORECAST PERIOD...LEADING TO A RISK
OF SHOWERS AND ISOLATED THUNDERSTORMS FROM AZ/NM INTO MO/IA.
...SOUTHWEST STATES...
THE STRONGEST FORCING ALOFT WILL SPREAD ACROSS PARTS OF SOUTHERN AZ
AND MUCH OF NM DURING THE DAY. THIS WILL LIKELY LEAD TO AN
EXPANDING AREA OF SHOWERS AND A FEW THUNDERSTORMS. DESPITE WEAK
INSTABILITY PROFILES...MODEL SOLUTIONS SUGGEST THAT THE LEFT EXIT
REGION OF THE UPPER JET WILL AFFECT PARTS OF SOUTHEAST AZ/SOUTHWEST
NM AROUND PEAK HEATING. A COMBINATION OF COLD TEMPS ALOFT AND
STRONG LIFT MIGHT YIELD AN ISOLATED STRONG THUNDERSTORM OR TWO
CAPABLE OF HAIL. ATTM...THE COVERAGE OF SEVERE STORMS DOES NOT
APPEAR TO WARRANT 5 PERCENT PROBABILITIES.
...CENTRAL PLAINS...
A POWERFUL LOW LEVEL JET WILL DEVELOP TONIGHT FROM TX INTO THE
CENTRAL PLAINS. STRONG LOW LEVEL WARM ADVECTION WILL OCCUR ALONG
THE SURFACE BAROCLINIC ZONE FROM THE TX PANHANDLE INTO MO/IA...WITH
SCATTERED CONVECTION EXPECTED. BY LATE TONIGHT /AFTER
06Z/...INCREASING LOW LEVEL MOISTURE WILL RESULT IN SLIGHTLY HIGHER
CAPE VALUES FROM SOUTHERN OK INTO SOUTHWEST MO...ALONG AND JUST EAST
OF THE SURFACE BOUNDARY. VERTICAL SHEAR PROFILES WOULD APPEAR TO
SUPPORT ORGANIZED OR EVEN SEVERE THUNDERSTORMS ALONG THIS AXIS.
HOWEVER...FORECAST SOUNDINGS SUGGEST THE WARM SECTOR WILL BE
SLIGHTLY CAPPED AND THAT THE BULK OF CONVECTION WILL BE ALONG OR
BEHIND THE FRONT. THIS SCENARIO WILL BE MONITORED THROUGH THE DAY
AND SEVERE PROBABILITIES MIGHT NEED TO BE ADDED IF WARM SECTOR
DEVELOPMENT APPEARS MORE LIKELY IN SUBSEQUENT MODEL GUIDANCE.
..HART/GARNER.. 12/13/2011
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