SWODY1
SPC AC 301958
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0258 PM CDT SUN AUG 30 2009
VALID 302000Z - 311200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER THE SOUTHEAST...
...SOUTHEAST...
SHOWERS AND THUNDERSTORMS CONTINUE FROM SERN LA/SERN MS ENEWD TO THE
ERN CAROLINAS...WHERE 1000 TO 2000 J/KG MIXED-LAYER CAPE IS NOW
INDICATED IN THE PRE-FRONTAL WARM SECTOR.
WITH 30 KT SWLYS AT MID-LEVELS OBSERVED THIS AFTERNOON...CAPE/SHEAR
COMBINATION REMAINS SUFFICIENT TO SUPPORT LOCALLY-ORGANIZED
STORMS/MULTICELL CLUSTERS. WITH THE EWD-MOVING UPPER FEATURE NOW
OVER CENTRAL MS TO CONTINUE SUPPORTING LOCALLY-WIDESPREAD
STORMS...WILL MAINTAIN SLIGHT RISK/15% SEVERE PROBABILITY THROUGH
EARLY EVENING.
...SRN ID...
SHOWERS AND SCATTERED THUNDERSTORMS CONTINUE ACROSS PARTS OF S
CENTRAL ID...ON THE ERN SIDE OF THE SMALL UPPER LOW NOW NEAR THE E
CENTRAL OREGON/SWRN ID BORDER. MODEST DESTABILIZATION WHICH IS
ONGOING ACROSS THIS AREA WILL CONTINUE TO SUPPORT WIDESPREAD -- AND
LOCALLY-VIGOROUS -- STORMS...WITH A FEW STRONGER STORMS CAPABLE OF
PRODUCING MARGINAL HAIL/WIND THROUGH MID-EVENING.
...WY SWD ACROSS ERN CO INTO NERN NM...
THOUGH LOW CLOUDS HAVE BEEN SLOW TO ERODE ACROSS THE HIGH
PLAINS...HEATING/DESTABILIZATION ACROSS THE HIGHER TERRAIN FROM WY
SWD INTO NM HAS CONTRIBUTED TO SCATTERED SHOWER/THUNDERSTORM
DEVELOPMENT. WHILE A MORE STABLE/CAPPED ENVIRONMENT OVER THE HIGH
PLAINS SHOULD GENERALLY HINDER APPRECIABLE SEWD DEVELOPMENT OFF THE
HIGH TERRAIN...MARGINAL THREAT FOR HAIL/WIND WITH ISOLATED
STRONGER/SEWD-MOVING STORMS WILL CONTINUE INTO THE EVENING. FOR
ADDITIONAL SHORT-TERM INFORMATION...PLEASE REFER TO SWOMCD 1985.
..GOSS.. 08/30/2009
.PREV DISCUSSION... /ISSUED 1125 AM CDT SUN AUG 30 2009/
...SOUTHEAST...
ALTHOUGH MID LEVEL LAPSE RATES REMAIN QUITE WEAK ACROSS THE REGION
TODAY...STRONG LOW LEVEL HEATING WILL OCCUR UNDER CLEAR SKIES. THIS
SHOULD STEEPEN LOW LEVEL LAPSE RATES AND BOOST MLCAPE INTO THE
1500-2500 J/KG RANGE AHEAD OF SUBTLE SHORTWAVE TROUGH MOVING ACROSS
MS/AL THIS MORNING...ALONG AND SOUTH OF STALLED SURFACE FRONT
EXTENDING FROM SERN VA INTO SRN MS. EXPECT GENERAL INCREASE IN
THUNDERSTORMS THROUGH THE AFTERNOON WITHIN WARM SECTOR AHEAD OF THIS
IMPULSE AND INVOF SEA BREEZE CIRCULATIONS. SWLY MID/UPPER LEVEL
FLOW WILL STRENGTHEN SOME DURING THE DAY OVER THE SOUTHEAST AND
SUPPORT AROUND 30 KT OF SFC-6 KM SHEAR SUGGESTING ORGANIZATION INTO
LINES/CLUSTERS. THE STEEPENING LOW LEVEL LAPSE RATES SHOULD ALSO
FOSTER ISOLATED STRONG/SEVERE WINDS AND PERHAPS MARGINALLY SEVERE
HAIL WITH THE STRONGER CORES INTO THE EARLY EVENING.
...SNAKE RIVER VALLEY REGION OF SRN ID...
COMPACT MID/UPPER LEVEL LOW AND ASSOCIATED ENHANCED SHEAR WILL
OVERSPREAD THIS AREA TODAY. CONVECTION SHOULD DEVELOP ONCE AGAIN
UNDER MID LEVEL COLD POCKET WHERE SURFACE HEATING WILL SUPPORT
MARGINAL INSTABILITY THIS AFTERNOON...WHILE ADDITIONAL DEVELOPMENT
COULD OCCUR FARTHER EAST INTO SERN ID AHEAD OF THIS IMPULSE.
APPEARS INSTABILITY WILL REMAIN FAIRLY MARGINAL FOR MORE THAN AN
ISOLATED SEVERE THUNDERSTORM...ALTHOUGH HAIL/WIND NEAR SEVERE LEVELS
CAN BE EXPECTED WITH THE STRONGER STORMS INTO THE EARLY TO MID
EVENING.
...CENTRAL-ERN CO INTO NERN NM INTO WY...
ONCE AGAIN...FAIRLY MOIST UPSLOPE FLOW WILL PERSIST INTO THE HIGHER
TERRAIN OF N-CENTRAL NM AND THE CO FRONT RANGE TODAY. MORNING
STRATUS HAS LINGERED NORTH OF THE PALMER DIVIDE INTO SERN
WY...ALTHOUGH THIS SHOULD ERODE EARLY TODAY AND ALLOW AXIS OF
MARGINAL INSTABILITY TO DEVELOP ALONG THE FRONT RANGE INTO PARTS OF
CENTRAL/WRN WY. EXPECT DIURNAL INCREASE IN THUNDERSTORMS OVER
HIGHER TERRAIN WITH MODEST FLOW ALOFT SUSTAINING SLOW MOVING STORMS
OVER LOWER ELEVATIONS INTO THE EVENING. SHEAR WILL BE STRONGER
WITHIN NWLY FLOW REGIME ALOFT OVER THE CENTRAL HIGH PLAINS INTO NERN
NM...AS WAS THE CASE YESTERDAY. HOWEVER...IT APPEARS CAPPING WILL
PERSIST OVER THE HIGH PLAINS AND LIMIT STORM SUSTENANCE AWAY FROM
THE HIGHER TERRAIN. REGARDLESS...STRONGER STORMS WILL ONCE AGAIN BE
CAPABLE OF ISOLATED SEVERE HAIL/WIND.
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