SWODY1
SPC AC 311236
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0736 AM CDT SUN AUG 31 2008
VALID 311300Z - 011200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE
INTERMOUNTAIN REGION...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE CENTRAL GULF
COAST...
...ERN ID/FAR WRN WY/NRN-CENTRAL UT/FAR E-CENTRAL NV...
CLOUDS/PRECIPITATION WILL LIKELY LINGER ACROSS MUCH OF THIS AREA
EARLY TODAY AHEAD OF DEEPENING SHORTWAVE TROUGH NOW MOVING ACROSS
THE PAC NW AND ASSOCIATED SURFACE COLD FRONT. SOME OF THIS EARLY
DAY ACTIVITY WILL LIKELY SHIFT EWD DURING THE AFTERNOON AS LEAD
IMPULSE EVIDENT ON WV IMAGERY NOW MOVING ACROSS NRN UT CONTINUES
NEWD. HOWEVER...FEED OF MID LEVEL MOISTURE AND RELATIVELY HIGH PW/S
EXTENDING OUT OF THE SOUTHWESTERN STATES SHOULD SUSTAIN SOME
CLOUDINESS AHEAD OF SURFACE COLD FRONT THROUGH THE
AFTERNOON....ESPECIALLY AS LOW AMPLITUDE WAVES SPREAD NNEWD TROUGH
THE DAY. REGARDLESS...SUFFICIENT HEATING SHOULD OCCUR ALONG WRN
PERIPHERY OF MID LEVEL MOISTURE FEED FOR MARGINAL INSTABILITY AND
SUPPORT INCREASED POTENTIAL FOR THUNDERSTORM DEVELOPMENT. ACTIVITY
SHOULD DEVELOP IN THE FORM OF SMALL LINES AND/OR A FEW MORE DISCRETE
CELLS AS DEEP LAYER SHEAR WILL BE QUITE STRONG. ALTHOUGH FAST
MOVING SURFACE FRONT MAY SUPPORT A MORE DOMINANT LINEAR EVOLUTION
WITH PRIMARY THREATS OF ISOLATED DAMAGING WINDS AND LARGE
HAIL...WITH SEVERE THREAT EXPECTED TO DWINDLE AFTER DARK.
...SRN/WRN FL INTO THE CENTRAL GULF COAST...
HURRICANE GUSTAV IS STILL ON TRACK TO MAKE LANDFALL NEAR THE END OF
THE FORECAST PERIOD OVER S-CENTRAL LA /REFERENCE LATEST GUIDANCE
FROM TPC/. LARGE AREA OF ENHANCED LOW LEVEL SHEAR WILL BEGIN
OVERSPREADING THE CENTRAL GULF COAST TODAY...AND STEADILY INCREASE
THE RISK OF A FEW TORNADOES AS OUTER RAINBANDS BEGIN IMPACTING THE
CENTRAL GULF COAST REGION THROUGH THE LATTER HALF OF THE PERIOD.
EARLY TODAY...FAVORABLE LOW LEVEL HODOGRAPHS MAY SUSTAIN ROTATION
WITH BAND OF STRONGER STORMS PERSISTING OVER SWRN FL. HOWEVER AS
GUSTAV SHIFTS INTO THE CENTRAL GULF...THIS RISK SHOULD SLOWLY
DIMINISH THROUGH THE DAY.
...ND...
AS A STRONG NE-SW COLD FRONT MOVES SLOWLY EWD ACROSS THE NRN
PLAINS...ASSOCIATED FRONTAL LOW IS FORECAST TO SHIFT ACROSS THE WRN
DAKOTAS. DESPITE THIS...A VERY STOUT CAP IS EXPECTED TO HINDER
CONVECTIVE DEVELOPMENT AND ASSOCIATED SEVERE POTENTIAL ALONG THIS
BOUNDARY S OF THE INTERNATIONAL BORDER. BEST CHANCE FOR STORMS
APPEARS TO EXIST ALONG AND NORTH OF THE FRONT...AS LOW LEVEL WAA
ASSOCIATED WITH A SLY LOW-LEVEL JET COULD RESULT IN AMPLE MOISTENING
ABOVE THE CAP TO ALLOW ELEVATED STORM DEVELOPMENT TO CREEP SWD INTO
NRN ND. ATTM...WILL MAINTAIN A LOW PROBABILITY HAIL THREAT...AS
INCREASING FLOW ALOFT WOULD PROVIDE SOME POTENTIAL FOR
ORGANIZED/ROTATING UPDRAFTS.
...CENTRAL/NRN HIGH PLAINS...
STRENGTHENING LEE TROUGH IS EXPECTED TO DEVELOP TODAY OVER THE
CENTRAL/NRN HIGH PLAINS AHEAD OF DEEPENING STRONG MID/UPPER LEVEL
TROUGH MOVING OUT OF THE PAC NW. STRONG HEATING/MIXING SHOULD
SUPPORT MARGINAL INSTABILITY WITHIN MODEST DEEP LAYER SHEAR THIS
AFTERNOON. IN ADDITION...DEEP ASCENT AHEAD OF SHORTWAVE TROUGH NOW
MOVING ACROSS NRN UT SHOULD BOOST POTENTIAL FOR THUNDERSTORMS OVER
PARTS OF ERN WY/WRN NE PANHANDLE INTO THE WRN DAKOTAS. STRONGER
STORMS MAY PRODUCE HAIL/WIND NEAR SEVERE LEVELS.
..EVANS/CROSBIE.. 08/31/2008
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