Tuesday, September 30, 2008

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 301258
SWODY1
SPC AC 301255

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0755 AM CDT TUE SEP 30 2008

VALID 301300Z - 011200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
AMPLIFIED...SLOWLY PROGRESSIVE WRN RIDGE/ERN TROUGH PATTERN WILL
PREVAIL OVER THE LWR 48 THIS PERIOD. JET STREAK NOW DROPPING SSE
INTO MN EXPECTED TO EVOLVE INTO A SHORTWAVE IMPULSE THAT SHOULD
REACH SRN IL BY 12Z WEDNESDAY AS LEAD IMPULSE NOW OVER OH WEAKENS
AND LIFTS NE ACROSS PA/NY. AT THE SFC...COLD FRONT IN ERN OH SHOULD
WEAKEN AS IT CROSSES THE NRN/CNTRL APPALACHIANS LATER TODAY...WITH
THE SRN PART LIKELY BECOMING NEARLY STATIONARY OR REDEVELOPING W
OVER CNTRL/ERN NC EARLY WEDNESDAY. FARTHER S...SRN STREAM JET AND A
WEAK SFC REFLECTION OF SAME WILL PERSIST OVER THE FL PENINSULA.

...MID ATLANTIC/APPALACHIANS/CAROLINAS...
HEIGHT FALLS WILL OCCUR THROUGH MUCH OF THE PERIOD FROM THE MID
ATLANTIC CST NWD INTO NY AND SE ONTARIO AS LEAD UPR IMPULSE OF
AMPLIFYING TROUGH PIVOTS NE ACROSS REGION. SCTD SHOWERS AND...WITH
SFC HEATING...TSTMS SHOULD ACCOMPANY/FOLLOW ASSOCIATED COLD FRONT AS
IT CONTINUES E TO THE ERN SLOPES OF THE NRN AND CNTRL APPALACHIANS
LATER TODAY. A FEW STORMS MAY ALSO FORM ALONG LEE TROUGH IN THE
CAROLINAS.

PREFRONTAL CLOUD BAND...AND HIGHER CLOUDS ASSOCIATED WITH SRN STREAM
JET...WILL TEMPER SFC HEATING ACROSS THE REGION.
NEVERTHELESS...COMBINATION OF COOL ADVECTION AT MID LEVELS AND NWD
MOVEMENT OF MOISTURE NOW OVER THE CNTRL AND ERN CAROLINAS SHOULD
YIELD SBCAPE ON THE ORDER OF 500-1000 J KG FROM ERN SC NNE TO THE
UPR CHESAPEAKE BAY.

DEEP SHEAR OVER THE E CNTRL U.S. WILL BE RATHER MODEST AS STRONGER
FLOW ALOFT REMAINS CONFINED TO DIGGING JET OVER THE UPR MS VLY. BUT
30+ KT MID LVL WSWLY FLOW COUPLED WITH MODEST INSTABILITY/FORCING
FOR ASCENT SHOULD SUPPORT ORGANIZATION OF STORMS INTO CLUSTERS/SHORT
LINES. THESE MULTICELL AND PERHAPS SHORT-LIVED SUPERCELL STRUCTURES
COULD PRODUCE MARGINALLY SVR HAIL AND/OR STRONG WINDS IN A FEW
SPOTS. A MORE PERSISTENT BAND OF STORMS COULD EVOLVE THIS EVE FROM
CNTRL/ERN MD NEWD INTO ERN PA/DE AND NJ AS DEEP FLOW BEGINS TO BACK
AND MORE SUBSTANTIAL LOW LVL MOISTURE SPREADS N INTO REGION.

...S FL...
CLOUDS ASSOCIATED WITH SRN STREAM JET AND OVERNIGHT MCS EXPECTED TO
LIMIT DIURNAL DESTABILIZATION OVER S FL TODAY. BUT CONTINUED NE
MOTION OF SRN STREAM TROUGH NOW OVER THE CNTRL GULF OF MEXICO WILL
MAINTAIN LARGE SCALE UVV AND MOISTURE INFLOW ACROSS REGION.
TSTMS SHOULD REDEVELOP INVOF WEAK FRONT OVER S FL...WHERE 30 KT
WSWLY DEEP SHEAR WILL BE SUFFICIENT FOR A FEW SUSTAINED/ORGANIZED
CLUSTERS. ISOLD LOCALLY DMGG WIND GUSTS OR PERHAPS A BRIEF
TORNADO/WATERSPOUT OR TWO CANNOT BE RULED OUT GIVEN RICH MOISTURE
AVAILABILITY. HOWEVER...OVERALL SVR THREAT APPEARS LOW.

..CORFIDI/HURLBUT.. 09/30/2008

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