SPC AC 281739
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1239 PM CDT MON AUG 28 2006
VALID 291200Z - 301200Z
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS DELMARVA/MID-ATLANTIC
REGION...
...SYNOPSIS...
SEASONALLY HIGH-AMPLITUDE AND PROGRESSIVE SYNOPTIC PATTERN WILL
PERSIST OVER MUCH OF CONUS THROUGH PERIOD. HEIGHTS WILL FALL ACROSS
PACIFIC NW IN ADVANCE OF TROUGH NOW EVIDENT IN MOISTURE CHANNEL
IMAGERY OVER SERN GULF OF AK AND ADJACENT NERN PACIFIC. MID-UPPER
LEVEL LOW NOW LOCATED INVOF YKN IS PROGGED TO MOVE ESEWD ACROSS
IL/INDIANA THROUGH PERIOD. CONFIDENCE IN THIS TRACK IS GAINED FROM
REASONABLY STRONG CONSENSUS AND LITTLE VARIATION AMONGST 28/12Z
DETERMINISTIC SHORT-RANGE MODELS...REGARDING LOCATION AND POSITIVE
TILT OF ASSOCIATED TROUGH. SOME DIFFERENCES ARE EVIDENT IN
STRENGTH...NAMELY WHETHER TROUGH WILL CONTINUE HOLDING CLOSED LOW OR
EVOLVE TO OPEN-WAVE STRUCTURE. ASSOCIATED SFC LOW -- NOW ANALYZED
OVER MO/IA BORDER -- IS FCST TO MOVE GENERALLY EWD ALONG FRONTAL
ZONE TO COASTAL DELMARVA/MID-ATLANTIC BY 30/00Z. TRAILING COLD
FRONT WILL MOVE SEWD OVER OH VALLEY...SRN/CENTRAL APPALACHIANS...AND
ALL BUT COASTAL PLAIN OF TX BY SAME TIME.
AS OF THIS WRITING...TS ERNESTO IS MOVING NWWD ACROSS SERN CUBA.
LATEST NHC TRACK FCST FOR ITS CENTER...AS WELL AS TRENDS IN THESE
FCSTS...SUGGEST MOST FAVORABLE AREA FOR TORNADOES WILL REMAIN
OFFSHORE OVER ATLANTIC. AS SUCH...NO PROBABILITIES ARE INCORPORATED
ATTM...THOUGH ANY LEFTWARD DEVIATION FROM THIS TRACK MIGHT RESULT IN
PERIPHERAL SUPERCELL POTENTIAL ALONG FL E COAST.
...MID-ATLANTIC/DELMARVA REGION...
WIDELY SCATTERED TSTMS ARE EXPECTED TO DEVELOP IN ZONE OF MAXIMIZED
LOW LEVEL ASCENT AND HEATING...SE THROUGH E OF SFC LOW...LATE
MORNING THROUGH AFTERNOON. THERE IS SOME CONCERN THAT CLOUD COVER
MAY LIMIT DIURNAL HEATING...HOWEVER WEAK CINH AND CONVERGENCE INVOF
LOW SHOULD SUPPORT ENOUGH SUPERCELL POTENTIAL TO WARRANT CATEGORICAL
SLGT RISK. MOST FAVORABLE ZONE FOR SVR SHOULD BE FROM LOW EWD INVOF
FRONT...WHERE SUPERCELLS ARE MOST PROBABLE. PRIND THIS AREA WILL
COMPRISE A NARROW CORRIDOR -- JUXTAPOSING NRN PERIPHERY OF MOST
FAVORABLE BOUNDARY LAYER HEATING/MOISTURE...SRN PERIPHERY OF
STRONGER MIDLEVEL FLOW...AND RELATIVELY BACKED LOW LEVEL WINDS IN
ORDER TO MAXIMIZE DEEP-LAYER VERTICAL SHEAR. ACCORDINGLY...MODEL
FCST SOUNDINGS INDICATE 35-35 KT EFFECTIVE SHEAR...AND 0-1 KM SRH
100-200 J/KG FOR EWD STORM MOTIONS. IN ENVIRONMENT OF RELATIVELY
LOW LCL AND FAVORABLE KINEMATIC PROFILES NEAR WARM FRONT...A TORNADO
OR TWO IS POSSIBLE. DAMAGING GUST THREAT MAINLY WOULD BE FROM
AFTERNOON CONVECTION WHOSE SUBCLOUD LAYERS ARE OPTIMALLY MIXED BY
HEATING. LOW-MIDLEVEL ABSOLUTE WARMTH AND LAPSE RATES NEAR
MOIST-ADIABATIC ALOFT WILL LIMIT BOTH RATE OF CONVECTIVE DEVELOPMENT
AND POTENTIAL FOR LARGE HAIL.
...MID-UPPER MS VALLEY REGION...
ALTHOUGH BOUNDARY LAYER WILL BE POSTFRONTAL AND CHARACTERIZED BY
AMBIENT CAA OVER THIS REGION...WIDELY SCATTERED TSTMS ARE POSSIBLE
DURING AFTERNOON..BENEATH COLD CORE REGION OF MID/UPPER LOW.
DIABATIC HEATING WILL OFFSET SFC CAA ENOUGH TO REMOVE CINH IN SOME
AREAS...IN COMBINATION WITH RESIDUAL/EVAPOTRANSPIRATED MOISTURE.
LAPSE RATES SHOULD BECOME STEEP ENOUGH TO SUPPORT MLCAPES LOCALLY
EXCEEDING 1000 J/KG. STRONGEST CELLS MAY PRODUCE HAIL AND GUSTS
NEAR SVR LEVELS.
...SRN AND PERHAPS CENTRAL AZ...
STRONG SFC HEATING IS ANTICIPATED ACROSS MUCH OF THIS REGION
CONCURRENT WITH INCREASE IN LOW LEVEL MOISTURE...SUPPORTING
CONVECTIVE POTENTIAL DURING MID-LATE AFTERNOON OVER HIGHER
ELEVATIONS AND LATE AFTERNOON INTO EVENING OVER LOWER DESERTS.
DEEP/LOW-MIDLEVEL ELY FLOW COMPONENT -- PARTICULARLY OVER SRN AZ --
WOULD AID MOVEMENT OF CONVECTION OFF MOUNTAINS AND OVER HOT/DEEPLY
MIXED DESERT BOUNDARY LAYERS...IN SUPPORT OF AT LEAST MRGL POTENTIAL
FOR STG-SVR GUSTS.
..EDWARDS.. 08/28/2006
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0800Z
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