SWODY1
SPC AC 140521
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1221 AM CDT MON SEP 14 2009
VALID 141200Z - 151200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
MOBILE SHORT WAVE TROUGH CURRENTLY MOVING ONTO THE CA COAST WILL
PROGRESS EWD THROUGH THE SIERRA NEVADA BEFORE DECELERATING AND
EVOLVING INTO A CLOSED CIRCULATION OVER THE GREAT BASIN. AS THIS
OCCURS...QUASI-STATIONARY DEEP-LAYER CYCLONE OVER TX WILL BEGIN TO
SLOWLY DRIFT EWD/NEWD.
...CNTRL GULF STATES...
SYNOPTIC PATTERN SIMILAR TO THAT OF THIS PAST WEEKEND WILL PERSIST
THROUGH THE PERIOD...FEATURING THE SLOW EWD MOVEMENT OF A SURFACE
LOW FROM E TX INTO LA. ASSOCIATED WARM FRONT WILL CONCURRENTLY
PIVOT NWWD THROUGH NRN PARTS OF MS/AL AND WRN TN TO VICINITY OF THE
MS RIVER. WARM SECTOR AIR MASS WILL CONTINUE TO BE CHARACTERIZED BY
BOUNDARY LAYER DEWPOINTS IN THE LOW/MID 70S AND PW VALUES AOA 2
INCHES. MIDLEVEL LAPSE RATES WILL REMAIN WEAK...BUT POCKETS OF
STRONGER HEATING COUPLED WITH THE ABUNDANT MOISTURE WILL CONTRIBUTE
TO MODERATE AFTERNOON INSTABILITY WITH MLCAPE OF 1000-2000 J/KG.
VORTICITY MAXIMA ROTATING AROUND PARENT UPPER LOW WILL LIKELY FOSTER
NUMEROUS DIURNAL TSTMS WITHIN SYSTEM WARM SECTOR...SOME OF WHICH MAY
BRIEFLY APPROACH SEVERE LEVELS. VERTICAL SHEAR /BOTH IN THE LOW
LEVELS AND THROUGH A DEEP LAYER/ WILL REMAIN SOMEWHAT MARGINAL FOR
STORM ORGANIZATION/ROTATION. NONETHELESS...A LOW PROBABILITY THREAT
FOR A BRIEF TORNADO AND/OR STRONG WIND GUSTS WILL EXIST WITH ANY
LONGER-LIVED STORMS.
...GREAT BASIN...
AIR MASS IS NOT FORECAST TO BE PARTICULARLY MOIST /PW VALUES AROUND
.75 INCH/...BUT THE PRESENCE OF STEEP LOW TO MIDLEVEL LAPSE RATES
WILL LARGELY CONTRIBUTE TO WEAK CONVECTIVE INSTABILITY LATER TODAY.
TSTMS ARE EXPECTED TO INCREASE IN COVERAGE THIS AFTERNOON AS FORCING
FOR ASCENT ASSOCIATED WITH SHORT WAVE TROUGH ACTS ON DESTABILIZING
ENVIRONMENT. A FEW OF THE STRONGER STORMS WILL BE CAPABLE OF SOME
HAIL AND GUSTY WINDS...THOUGH THE WEAK CONVECTIVE INSTABILITY SHOULD
LIMIT A MORE ORGANIZED SEVERE THREAT.
..MEAD/JEWELL.. 09/14/2009
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