Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS03 KWNS 260704
SWODY3
SPC AC 260703

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0203 AM CDT TUE MAY 26 2015

VALID 281200Z - 291200Z

...THERE IS A MRGL RISK OF SVR TSTMS ACROSS NRN NEW ENGLAND...

...THERE IS A MRGL RISK OF SVR TSTMS ACROSS THE PLAINS AND MS
VALLEY...

...SUMMARY...
SCATTERED THUNDERSTORMS WILL DEVELOP ACROSS MUCH OF THE CONUS DURING
THE DAY3 PERIOD.  THE GREATEST RISK FOR STRONG STORMS WILL BE ACROSS
THE PLAINS AND MISSISSIPPI VALLEY AND OVER NORTHERN NEW ENGLAND.

...NRN NEW ENGLAND...

QB-NY SHORT-WAVE TROUGH WILL EJECT EWD EARLY IN THE PERIOD FORCING
SFC FRONT THROUGH NWRN MAINE BY 18Z.  BOUNDARY LAYER HEATING AHEAD
OF COLD FRONT SHOULD PROVE ADEQUATE...ALONG WITH FRONTAL CONVERGENCE
FOR SCT THUNDERSTORMS ALONG THE WIND SHIFT.  FORECAST SOUNDINGS
ACROSS THE WARM SECTOR OVER MAINE SUGGEST SUFFICIENT INSTABILITY FOR
ROBUST UPDRAFTS...ESPECIALLY GIVEN THE ASSIST FROM SHORT-WAVE TROUGH
AND SFC-6KM FLOW ON THE ORDER OF 35KT.  HAVE INTRODUCED MRGL RISK
FOR DAMAGING WINDS WITH CONVECTION THAT EVOLVES ALONG SURGING COLD
FRONT.  THIS ACTIVITY SHOULD PUSH OFFSHORE BY 29/00Z.

...PLAINS...

COMPLICATED CONVECTIVE SCENARIO WILL EVOLVE DURING THE DAY3 PERIOD
ACROSS THE INTERIOR U.S...FROM THE NRN PLAINS TO TX.  WEAK SPLIT
FLOW REGIME WILL LIKELY INDUCE CONSIDERABLE AMOUNT OF CONVECTION
ACROSS THE PLAINS/MS VALLEY REGION DUE PARTLY TO WEAK INHIBITION AND
AMPLE BOUNDARY LAYER HEATING.  LATEST MODEL GUIDANCE SUGGESTS WEAK
FORCING WILL BE OBSERVED ACROSS THE NRN PLAINS/UPPER MS VALLEY AHEAD
OF SHORT WAVE AND LIKEWISE ACROSS WEST TX WITH A FEATURE THAT WILL
PROGRESS FROM NRN MEXICO INTO THE BIG BEND REGION BY EARLY EVENING.
FORECAST MID-LEVEL FLOW ACROSS THE PLAINS IS QUITE WEAK WITH 500MB
SPEEDS ON THE ORDER OF 20KT IN MANY PLACES.  POCKETS OF STRONGER
FLOW LIKELY REFLECT CONVECTION IN THE MODELS AND AMPLE INSTABILITY
SHOULD SUPPORT SEVERE TSTMS.  HOWEVER...FORECAST STEERING CURRENTS
ARE JUST TOO WEAK TO JUSTIFY MORE THAN 5 PERCENT SEVERE FOR A DAY3
OUTLOOK.  LARGE HAIL WOULD BE THE PRIMARY THREAT WITH CONVECTION
ACROSS THIS REGION.

..DARROW.. 05/26/2015




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