SWODY1
SPC AC 120509
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1209 AM CDT FRI OCT 12 2007
VALID 121200Z - 131200Z
..NO SVR TSTM AREAS FORECAST...
..SYNOPSIS...
LARGE AND PROGRESSIVE UPPER TROUGH WILL CROSS THE WEST COAST TODAY
AND CONTINUE TO MOVE OVER THE GREAT BASIN AND INTERMOUNTAIN REGIONS
THROUGH TONIGHT. DOWNSTREAM RIDGE ACROSS THE CNTRL STATES WILL
PERSIST GIVEN SLOW DEAMPLIFICATION/EWD TRANSLATION OF COMPLEX
DEEP-LAYER CYCLONE AFFECTING ERN GREAT LAKES AND NORTHEAST. CLOSER
TO THE SURFACE...HIGH PRESSURE AREA WILL EXTEND FROM THE MS VALLEY
TO THE SOUTHEAST. MOIST AXIS ON THE WRN/SWRN FLANK OF THIS HIGH WILL
CONTINUE TO GRADUALLY EXPAND NWD FROM TX TO THE CNTRL PLAINS ON
PERSISTENT SLY LOW LEVEL JET. LEE CYCLOGENESIS AND WARM
FRONTOGENESIS WILL BECOME INCREASINGLY LIKELY OVER CO/KS FROM LATE
AFTERNOON THROUGH TONIGHT AS STRONGER LARGE SCALE FORCING ASSOCIATED
WITH THE APPROACH OF WRN TROUGH MOVES OVER THESE AREAS.
..KS/MID MISSOURI RIVER VALLEY...
A FEW STORMS MAY BE ONGOING EARLY TODAY OVER KS AIDED BY FOCUSED
ISENTROPIC ASCENT ON THE NOSE OF THE LOW LEVEL JET. A FEW CLUSTERS
OF ELEVATED STORMS MAY PERSIST IN THIS ZONE...OR NEW DEVELOPMENT MAY
OCCUR...AS WARM FRONT BECOMES BETTER DEFINED ACROSS THE REGION LATER
TODAY. INFLUX OF INCREASINGLY UNSTABLE AIR ACROSS THE WARM FRONT MAY
ENHANCE UPDRAFT STRENGTH THROUGH THE LATE AFTERNOON AND INTO EVENING
WITH A COUPLE OF SEVERE HAIL EVENTS POSSIBLE. WITH GENERALLY WEAK
LARGE SCALE FORCING ACROSS THE WARM SECTOR THROUGH THE
AFTERNOON...POTENTIAL FOR SURFACE-BASED CONVECTION APPEARS LOW.
STORM COVERAGE IS EXPECTED TO INCREASE THROUGH FRIDAY NIGHT ACROSS
THE CNTRL PLAINS AS INTENSIFYING LOW LEVEL JET MAINTAINS MOISTURE
FLUX AND LARGE SCALE ASCENT STRENGTHENS. STEEPENING MID LEVEL LAPSE
RATES AND EFFECTIVE SHEAR OF 30-40KT SUGGEST HAIL MAY ACCOMPANY A
FEW OF THE STRONGER STORMS.
..SRN HIGH PLAINS...
WHILE EFFECTIVE SHEAR AND STRONG INSTABILITY ARE FORECAST TO BE
SUFFICIENT FOR ORGANIZED STORMS ACROSS THE SRN HIGH PLAINS FRIDAY
AFTERNOON LATEST GUIDANCE REMAINS CONSISTENT WITH EARLIER
INDICATIONS THAT ONLY ISOLATED DEVELOPMENT MAY OCCUR WITH DIURNAL
HEATING. THIS APPEARS LIKE A REASONABLE SCENARIO GIVEN LACK OF
GREATER SYNOPTIC FORCING AND WEAK LOW LEVEL CONVERGENCE. LOW
PROBABILITY HAIL FORECAST APPEARS ADEQUATE WITH ONLY ISOLATED
SUPERCELL POTENTIAL EXPECTED.
.CARBIN/GRAMS.. 10/12/2007
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