SWODY2
SPC AC 130545
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1245 AM CDT SUN SEP 13 2009
VALID 141200Z - 151200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
LARGE-SCALE/LONGWAVE UPPER RIDGING IS FORECAST ACROSS MOST OF THE
U.S. THIS PERIOD...BETWEEN A LARGE TROUGH OVER THE NORTHEAST AND A
SECOND OVER THE NERN PACIFIC. WITHIN THE LARGE-SCALE RIDGE
HOWEVER...SEVERAL SMALLER-SCALE FEATURES ARE FORECAST -- INCLUDING
THREE SEPARATE MID-LEVEL LOWS. THE FIRST -- PROGGED TO DRIFT VERY
SLOWLY EWD ACROSS THE S CENTRAL U.S. -- WILL MAINTAIN A WEAK SURFACE
LOW INVOF SRN LA. THIS LOW...AND A WEAK WARM FRONT EXTENDING EWD
ACROSS THE GULF COAST REGION...WILL SERVE AS A FOCUS FOR WIDESPREAD
RAIN AND EMBEDDED THUNDERSTORMS. THE SECOND LOW IS PROGGED TO
CONTINUE SHIFTING NWD OUT OF MT AND ACROSS SRN ALBERTA. THE THIRD
LOW IS FORECAST TO MOVE ACROSS CA AND INTO NV THROUGH THE DAY AS A
WEAKENING SHORT-WAVE TROUGH. OVERNIGHT...THE FEATURE SHOULD EVOLVE
MORE INTO A CLOSED/CUT-OFF LOW...MOVING INTO UT THROUGH THE SECOND
HALF OF THE PERIOD. THIS TROUGH/LOW SHOULD ALSO CONTRIBUTE TO
FAIRLY WIDESPREAD SHOWERS AND STORMS OVER THE INTERMOUNTAIN WEST --
PRIMARILY DURING THE AFTERNOON AND EARLY EVENING.
A VERY LIMITED SEVERE THREAT WILL BE POSSIBLE ACROSS THE GULF COAST
REGION INVOF THE SURFACE LOW/WARM FRONT WHERE A VERY MOIST BOUNDARY
LAYER IS PROGGED. WITH THE POTENTIAL FOR SLIGHTLY ENHANCED SHEAR
NEAR AND TO THE COOL SIDE OF THE WARM FRONT...AN ISOLATED
STRONGER/ROTATING STORM CANNOT BE RULED OUT. FARTHER W ACROSS UT
AND VICINITY...FAVORABLE DEEP-LAYER SHEAR SHOULD EVOLVE THROUGH
AFTERNOON AHEAD OF THE APPROACHING UPPER FEATURE. HOWEVER...ATTM
INSTABILITY IS FORECAST TO BE QUITE LIMITED...PRECLUDING FOR NOW THE
INTRODUCTION OF SEVERE PROBABILITIES.
..GOSS.. 09/13/2009
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