Wednesday, September 14, 2011

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 140600
SWODY1
SPC AC 140558

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1258 AM CDT WED SEP 14 2011

VALID 141200Z - 151200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
POTENT/SMALL-SCALE UPPER TROUGH WILL CONTINUE DIGGING ESEWD ACROSS
THE ONTARIO AND THE ADJACENT UPPER GREAT LAKES REGION...AND
EVENTUALLY EWD INTO QUEBEC/SEWD INTO THE MIDWEST. AHEAD OF THE
TROUGH...A COLD FRONT WILL CONTINUE SHIFTING SEWD...STRETCHING FROM
NEW ENGLAND SWWD TO N TX DURING THE AFTERNOON. BY THE END OF THE
PERIOD...THE FRONT WILL HAVE SURGED SWD ACROSS TX AND INTO THE GULF
COAST STATES...AND EWD OFF THE NEW ENGLAND COAST...AS A LARGE/COOL
CANADIAN HIGH SETTLES SWD INTO THE CENTRAL CONUS.

MEANWHILE IN THE W...A WEAK/PERSISTENT UPPER LOW WILL SHIFT SLOWLY
EWD ACROSS AZ AND VICINITY THROUGH THE PERIOD.

...COASTAL NEW ENGLAND SWWD INTO THE CENTRAL APPALACHIANS...
AFTERNOON DESTABILIZATION IS FORECAST FROM ERN NEW ENGLAND SWWD INTO
THE CENTRAL APPALACHIANS AHEAD OF THE ADVANCING SURFACE
FRONT...WHICH WILL FUEL SCATTERED AFTERNOON STORM DEVELOPMENT.
HOWEVER...MOST OF THE STRONGER FLOW ALOFT WILL REMAIN TO THE COOL
SIDE OF THE FRONT -- RESULTING IN GENERALLY MODEST SHEAR WITHIN THE
ZONE OF STORM INITIATION. STILL...A FEW STRONGER STORMS/LINE
SEGMENTS MAY EVOLVE...WITH POTENTIAL FOR ISOLATED WIND DAMAGE AND/OR
MARGINAL HAIL. WILL INTRODUCE A NARROW CORRIDOR OF 5% SEVERE
PROBABILITY NWD INTO ERN NEW ENGLAND...AND MAINTAIN LOW SEVERE
PROBABILITY AS FAR W AS WV.

...MID MS VALLEY REGION...
VORT MAX MOVING ESEWD ACROSS KS/MO EARLY IN THE PERIOD IS PROGGED TO
INDUCE WEAK CYCLOGENESIS ALONG THE TRAILING COLD FRONT INVOF THE MID
MS VALLEY DURING THE AFTERNOON. MODEST DESTABILIZATION AND MORE
FOCUSED UVV IN THIS REGION SHOULD SUPPORT AN INCREASE IN CONVECTION
DURING THE AFTERNOON...AND ENHANCED SHEAR SHOULD BE SUFFICIENT FOR
MULTICELL ORGANIZATION OR EVEN A WEAK SUPERCELL OR TWO.
ATTM...QUESTIONS REGARDING DESTABILIZATION POTENTIAL DUE TO ONGOING
CLOUDS/PRECIPITATION SUGGEST MAINTAINING ONLY LOW PROBABILITY SEVERE
THREAT IN THIS REGION. HOWEVER...UPGRADE TO A SMALL SLIGHT RISK
COULD BE NEEDED IN LATER OUTLOOKS IF AMPLE HEATING/DESTABILIZATION
APPEARS MORE LIKELY IN THIS REGION.

...ERN NM/PORTIONS OF NWRN TX...
WEAK POST-FRONTAL UPSLOPE FLOW REGIME IS FORECAST TO EVOLVE ACROSS
NWRN TX AND ERN NM DURING THE AFTERNOON AS THE SURFACE BOUNDARY
PUSHES SWD...LIKELY SUPPORTING SCATTERED CONVECTIVE DEVELOPMENT
ACROSS THIS AREA. ATTM...IT APPEARS THAT DESTABILIZATION SHOULD
REMAIN LIMITED...HINDERING THE OVERALL SEVERE THREAT. STILL...WITH
VEERING/INCREASING FLOW WITH HEIGHT ACROSS THIS AREA...SHEAR WILL
SUPPORT POTENTIAL FOR A FEW STRONGER CELLS CAPABLE OF GUSTY WINDS
AND/OR MARGINAL HAIL DURING THE AFTERNOON/EVENING.

..GOSS/COHEN.. 09/14/2011

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