Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS01 KWNS 261941
SWODY1
SPC AC 261940

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0240 PM CDT MON SEP 26 2016

VALID 262000Z - 271200Z

...THERE IS A MRGL RISK OF SVR TSTMS LATE THIS AFTERNOON ACROSS THE
CENTRAL APPALACHIANS REGION...

...SUMMARY...
THUNDERSTORMS ACROSS THE CENTRAL APPALACHIANS REGION LATE THIS
AFTERNOON MAY BE ACCOMPANIED BY LOCALLY STRONG SURFACE GUSTS.

...20Z OUTLOOK UPDATE...
LARGE-SCALE ASCENT AHEAD OF AMPLIFIED UPSTREAM MID/UPPER
TROUGHING...INSOLATION AND OROGRAPHY HAVE CONTRIBUTED TO SUFFICIENT
DESTABILIZATION FOR SCATTERED ONGOING THUNDERSTORMS IN THE VICINITY
OF THE APPALACHIANS THIS AFTERNOON.  DUE TO WEAK MID-LEVEL LAPSE
RATES...WHICH ARE ONLY SUPPORTING WEAK CAPE...ACTIVITY IS NOT
PARTICULARLY STRONG...AND POTENTIAL FOR SUBSTANTIVE FURTHER
INTENSIFICATION THIS AFTERNOON SEEMS LIMITED.

AS A BELT OF STRONGER SOUTHWESTERLY MID-LEVEL FLOW IN THE BASE OF
THE UPPER TROUGH NOW APPROACHES AREAS AS FAR SOUTH AS THE CENTRAL
APPALACHIANS...THE PRESENCE OF CONVECTION DOES POSE SOME POTENTIAL
FOR EVENTUAL DOWNWARD MIXING OF HIGHER MOMENTUM TO THE SURFACE.
HOWEVER...BASED ON MODEL OUTPUT AND OBSERVATIONAL DATA...THE
STRENGTH OF THIS FLOW NEAR ONGOING CONVECTION IS GENERALLY ONLY
AROUND 30-40 KT IN THE 700-500 MB LAYER...WITH FLOW MUCH WEAKER IN
LOWER LEVELS.  AS A RESULT...WHILE ISOLATED SURFACE GUSTS
APPROACHING SEVERE LIMITS MAY NOT BE OUT OF THE QUESTION IN STRONGER
CELLS...POTENTIAL FOR GUSTS EXCEEDING SEVERE LIMITS APPEARS FAIRLY
LOW.  EVEN SO...MOSTLY FOR THE SAKE OF CONTINUITY AT THIS POINT...5
PERCENT SEVERE PROBABILITIES WILL BE MAINTAINED ACROSS THE CENTRAL
APPALACHIANS REGION FOR THE REMAINDER OF THE AFTERNOON.

..KERR.. 09/26/2016

.PREV DISCUSSION... /ISSUED 1043 AM CDT MON SEP 26 2016/

A LARGE UPPER TROUGH IS MOVING EASTWARD ACROSS THE GREAT LAKES
REGION TODAY...WITH AN ASSOCIATED COLD FRONT SWEEPING ACROSS THE OH
VALLEY AND CENTRAL APPALACHIANS.  DEEP MOISTURE AHEAD OF THE FRONT
WILL RESULT IN SCATTERED SHOWERS AND THUNDERSTORMS FROM THE GULF
COAST INTO THE UPPER OH VALLEY AND CENTRAL APPALACHIANS TODAY AND
TONIGHT.  IN GENERAL...THERMODYNAMIC PARAMETERS ARE MARGINAL FOR ANY
ORGANIZED SEVERE THREAT DUE TO WEAK LAPSE RATES AND POCKETS OF
CLOUDS.  IT APPEARS THE AREA MOST LIKELY TO SEE A STRONG STORM OR
TWO IS OVER PARTS OF WV AND ADJACENT STATES...WHERE THE SOUTHERN
FRINGE OF STRONGER WESTERLIES OVERLAPS WITH SUFFICIENT CAPE VALUES
FOR A LOW RISK OF LOCALLY DAMAGING WIND GUSTS.  OTHERWISE...NO
ORGANIZED SEVERE STORMS ARE EXPECTED.

$$


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