Severe Storm Outlook Narrative (AC)
Issued by NWS

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567
ACUS01 KWNS 261241
SWODY1
SPC AC 261240

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0740 AM CDT MON SEP 26 2016

VALID 261300Z - 271200Z

...THERE IS A MRGL RISK OF SVR TSTMS PORTIONS UPPER OH VALLEY AND
NEARBY APPALACHIANS...

...SUMMARY...
A FEW STRONG TO SEVERE THUNDERSTORMS MAY OCCUR THIS AFTERNOON ACROSS
PARTS OF THE UPPER OHIO RIVER VALLEY AND IN THE NEARBY APPALACHIANS.

...SYNOPSIS...
UPPER-AIR SCHEME THROUGH PERIOD WILL BE CHARACTERIZED BY REX PATTERN
OVER WRN CONUS/NWRN MEX...AND HEIGHT FALLS OVER MUCH OF ERN CONUS
AHEAD OF ENLARGING/INTENSIFYING GREAT LAKES CYCLONE.  ASSOCIATED
UPPER-LEVEL LOW -- NOW EVIDENT IN MOISTURE-CHANNEL IMAGERY OVER NWRN
ONT JUST N OF MN BORDER -- IS FCST TO WOBBLE ERRATICALLY ESEWD
TOWARD NRN LS THROUGH PERIOD...NEARLY STACKED WITH SFC CYCLONE.
MEANWHILE ASSOCIATED CYCLONIC-FLOW FIELD EXPANDS TO COVER AREAS FROM
NRN PLAINS TO WRN NEW ENGLAND AND SRN APPALACHIANS NWD.

AS THAT OCCURS...ASSOCIATED SFC COLD FRONT -- ANALYZED AT 11Z FROM
OCCLUSION TRIPLE POINT OVER WRN OH SWD ACROSS WRN TN...NWRN LA AND
MIDDLE/LOWER TX COASTAL PLAIN -- WILL MOVE EWD/SEWD THROUGH PERIOD.
BY 00Z FRONT SHOULD BE LOCATED OVER WRN NY...WRN/CENTRAL PA...SRN
WV...ERN TN...SRN MS...AND SRN LA.  BY 12Z FRONT SHOULD REACH NEW
ENGLAND...DELMARVA...NRN GA...FL PANHANDLE...N-CENTRAL GULF.  WARM
FRONT INITIALLY OVER ERN PORTIONS KY/TN AND WRN NC SHOULD MOVE
IRREGULARLY ENEWD...AS TRIPLE POINT MIGRATES ERRATICALLY ACROSS NRN
WV OR SWRN PA...THEN ROUGHLY OVER LOWER POTOMAC RIVER AREA THROUGH
PERIOD.

...UPPER OH VALLEY AND NEARBY APPALACHIANS...
SCATTERED TSTMS ARE EXPECTED TO DEVELOP THIS AFTN IN NE-SW BAND...
ROUGHLY PARALLEL TO AND ALONG OR SLIGHTLY AHEAD OF SFC COLD FRONT.
THIS MAY BE EITHER TEMPORAL TRANSLATION OF ONGOING ACTIVITY OVER
OH/SERN INDIANA/WRN KY...OR ADDITIONAL DEVELOPMENT WITHIN SAME
GENERAL PLUME OF LARGE-SCALE ASCENT AND FRONTAL FORCING.  THOUGH
AVBL INSTABILITY WILL BE LIMITED...A FEW CELLS WITHIN THIS BAND MAY
PRODUCE DAMAGING GUSTS NEAR SVR LIMITS.

NARROW/FOREGOING WARM SECTOR IS EXPECTED TO BE CHARACTERIZED BY SFC
DEW POINTS 60S F...AND SUFFICIENT SFC DIABATIC HEATING TO OFFSET
WEAK MID/UPPER-LEVEL LAPSE RATES AND YIELD SFC-BASED EFFECTIVE-
INFLOW PARCELS.  MLCAPE 300-800 J/KG IS ANTICIPATED...AMIDST
ESSENTIALLY UNIDIRECTIONAL LOW/MIDDLE-LEVEL WIND PROFILES SW OF WARM
FRONT.  INSTABILITY GRADUALLY WILL BECOME NEUTRAL TO NEGATIVE FOR
SFC PARCELS POLEWARD OF TRIPLE POINT.  DEEP SHEAR WILL BE INCREASING
WITH TIME...AS UPPER CYCLONE APCHS...THOUGH STRONGEST VALUES SHOULD
REMAIN BEHIND SFC COLD FRONT.  FCST SOUNDINGS SHOW EFFECTIVE-SHEAR
MAGNITUDES STRUGGLING TO REACH 30 KT...AND OVERALL ORGANIZATION OF
ACTIVITY SHOULD BE LIMITED AND GENERALLY MULTICELLULAR IN CHARACTER.

..EDWARDS/PICCA.. 09/26/2016

$$



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