Tuesday, September 16, 2008

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 161732
SWODY2
SPC AC 161730

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1230 PM CDT TUE SEP 16 2008

VALID 171200Z - 181200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
UPPER AIR PATTERN FCST TO REMAIN CHARACTERIZED BY RIDGING FROM
INTERIOR NWRN CONUS TO S-CENTRAL PLAINS AND TROUGHING FROM QUE TO
NERN GULF...THOUGH EACH WILL LOSE AMPLITUDE GRADUALLY THROUGH
PERIOD. SRN PORTION OF DIFFUSE/POSITIVELY-TILTED TROUGH --
INITIALLY ANALYZED FROM LOWER GREAT LAKES TO NRN AL TO CENTRAL TX --
WILL MOVE SLOWLY ESEWD ACROSS GA/SC AND ERN GULF COAST
REGION....WITH TRAILING PORTION QUASISTATIONARY ACROSS CENTRAL/W TX.
SHORTWAVE TROUGH -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY
OFFSHORE CENTRAL/NRN CA -- IS FCST TO DEAMPLIFY AS IT EJECTS NNEWD
OVER NRN CA AND ORE DAY-2...AHEAD OF PROGRESSIVE NERN PACIFIC UPPER
LOW.

AT SFC...CURRENTLY QUASISTATIONARY FRONTAL ZONE -- ANALYZED FROM
OFFSHORE NERN NC SWWD ACROSS SC AND SRN GA TO W-CENTRAL GULF -- IS
FCST TO DRIFT SWD AS WEAK UPPER TROUGHING MOVES OVER SERN CONUS.
NRN STREAM COLD FRONT -- ANALYZED ATTM FROM FAR NWRN ONT SWWD ACROSS
ND -- SHOULD MOVE SEWD OVER UPPER GREAT LAKES AND ST. LAWRENCE
VALLEY THIS PERIOD...REACHING VICINITY NRN NY...NWRN PA...OH AND
INDIANA BY 18/12Z. ATTM MOISTURE APPEARS TOO WEAK TO SUPPORT GEN
THUNDER RISK AREA ALONG THIS FRONT...HOWEVER VERY ISOLATED/BRIEF
CONVECTION DEEP ENOUGH FOR LIGHTNING CANNOT BE RULED OUT.

...SERN CONUS...
SCATTERED TSTMS ARE EXPECTED AGAIN DAY-2 INVOF FRONTAL ZONE.
PRECURSORY REGIME OF WEAK LOW-MIDLEVEL LAPSE RATES WILL BE
DESTABILIZED WEAKLY BY LARGE SCALE ASCENT IMMEDIATELY PRECEDING
UPPER TROUGH. POCKETS OF WEAK DIABATIC HEATING AMIDST BKN CLOUD
COVER...ALONG WITH SUFFICIENT FRONTAL FORCING...WEAK SBCINH AND RICH
LOW LEVEL MOISTURE...WILL SUPPORT CONVECTIVE POTENTIAL.
ADDITIONALLY...WIDELY SCATTERED TSTMS SHOULD FORM IN WARM SECTOR
ALONG SEA BREEZE AND OUTFLOW BOUNDARIES. ALTHOUGH LOW-MIDLEVEL
WINDS AND BULK SHEAR EACH WILL REMAIN RATHER WEAK...BELT OF 50-65 KT
UPPER LEVEL WINDS FROM CENTRAL/NRN FL TO EXTREME SRN GA MAY AID
STORM VENTILATION ALOFT AND SUPPORT SOMEWHAT ORGANIZED MULTICELLULAR
CONVECTION...WITH POTENTIAL FOR ISOLATED DAMAGING GUSTS.

...WRN CONUS...
PRIMARILY DIURNAL CONVECTIVE POTENTIAL WILL BE MAXIMIZED OVER HIGHER
TERRAIN. DIABATIC SFC HEATING AND AT LEAST MRGL LOW LEVEL MOISTURE
WILL COMBINE WITH STEEP LOW-MIDLEVEL LAPSE RATES TO YIELD MLCAPES
GENERALLY BELOW 500 J/KG MOST AREAS...BUT STILL SUFFICIENT TO
SUPPORT HIGH BASED CB. SUBTLE DESTABILIZATION FROM EJECTING
MID-UPPER SHORTWAVE TROUGH ALSO MAY CONTRIBUTE TO CONVECTIVELY
FAVORABLE ENVIRONMENT OVER INTERIOR PORTIONS PACIFIC NW. SOME STG
GUSTS ARE POSSIBLE FROM TSTMS MOVING OVER RELATIVELY WELL-MIXED/DEEP
BOUNDARY LAYERS OF LOWER ELEVATIONS...HOWEVER SVR POTENTIAL APPEARS
TOO BRIEF/ISOLATED ATTM TO JUSTIFY ANY PARTICULAR AREA OF AOA
5-PERCENT SVR PROBABILITIES.

..EDWARDS.. 09/16/2008

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