Severe Storm Outlook Narrative (AC)
Issued by NWS

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000
ACUS01 KWNS 310551
SWODY1
SPC AC 310550

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1250 AM CDT THU JUL 31 2014

VALID 311200Z - 011200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF NEW
ENGLAND...

...SUMMARY...
STORMS MAY PRODUCE ISOLATED LARGE HAIL AND LOCALLY STRONG WIND GUSTS
ACROSS NEW ENGLAND TODAY. A FEW STRONG STORMS ARE ALSO POSSIBLE OVER
EASTERN TEXAS...THE SOUTHERN ROCKIES AND WESTERN OREGON.

...SYNOPSIS...

BLOCKING PATTERN WILL PERSIST THURSDAY WITH A LARGE UPPER LOW OVER
THE EASTERN HALF OF THE U.S. AND AN UPSTREAM RIDGE OVER MUCH OF THE
WESTERN STATES. A SHORTWAVE TROUGH EMBEDDED WITHIN THE UPPER LOW IS
NOW DROPPING INTO THE GREAT LAKES. THIS FEATURE WILL MOVE THROUGH
NEW ENGLAND LATER THURSDAY MORNING INTO THE AFTERNOON. AT THE SFC A
COLD FRONT WILL CONTINUE SEWD THROUGH TEXAS...LIKELY EXTENDING FROM
NERN TX SWWD INTO THE BIG BEND AREA BY AFTERNOON. QUASI-STATIONARY
FRONT SHOULD EXTEND FROM FL NWWD INTO THE LOWER MS VALLEY AND NERN
TX WHERE IT WILL INTERSECT THE COLD FRONT.

...NEW ENGLAND AREA...

A THERMAL TROUGH WITH -16 TO -18C AT 500 MB WILL SPREAD ACROSS NEW
ENGLAND THURSDAY. NEAR SFC DEWPOINTS IN THE 50S AND POCKETS OF
MODEST BOUNDARY LAYER WARMING SHOULD BOOST MLCAPE TO 500-700 J/KG BY
LATE MORNING. WEAK CAP AND DESTABILIZING BOUNDARY LAYER ALONG WITH
ASCENT ATTENDING THE SHORTWAVE TROUGH SHOULD CONTRIBUTE TO
DEVELOPMENT OF NUMEROUS THUNDERSTORMS DURING THE DAY. A 40-50 KT
MID-LEVEL JET ACCOMPANYING THE SHORTWAVE TROUGH WILL RESULT IN
SUFFICIENT /35-45 KT/ DEEP SHEAR FOR SUPERCELLS WITH LARGELY
UNIDIRECTIONAL PROFILES SUPPORTIVE OF A FEW STORM SPLITS. SOME
STORMS COULD ALSO EVOLVE INTO BOWING SEGMENTS. ISOLATED LARGE HAIL
AND STRONG WIND GUSTS WILL BE THE MAIN THREATS THROUGH AT LEAST
MID-AFTERNOON.

...EASTERN TEXAS AND THE ARKLATEX REGION...

SHORTWAVE TROUGH OVER OK WILL ADVANCE SEWD INTO THE LOWER MS VALLEY
WITH TRAILING COLD FRONT MOVING INTO ERN TX. WHILE MID-LEVEL LAPSE
RATES WILL REMAIN WEAK...DIABATIC WARMING OF THE VERY MOIST SFC
LAYER SHOULD CONTRIBUTE TO 1000-1500 J/KG MLCAPE IN PRE-FRONTAL WARM
SECTOR. STORMS SHOULD REDEVELOP ALONG THE FRONT BY AFTERNOON ACROSS
ERN TX. STRONGER VERTICAL SHEAR WILL REMAIN IN THE MORE STABLE
REGIME NORTH OF THE STATIONARY FRONT WITH WEAKER 25-30 KT SHEAR
FARTHER SOUTH INTO TX. STORMS SHOULD REMAIN MOSTLY MULTICELL IN
CHARACTER...BUT SOME MARGINAL SUPERCELL STRUCTURES WILL BE POSSIBLE.
ISOLATED STRONG TO DAMAGING WIND GUSTS WILL BE THE MAIN THREAT.

...WESTERN OREGON...

STORMS WILL LIKELY ONCE AGAIN DEVELOP OVER THE CASCADES OF WRN
OREGON DURING THE AFTERNOON. DEEPLY MIXED INVERTED-V BOUNDARY LAYERS
WILL SUPPORT A THREAT FOR ISOLATED DOWNBURST WINDS.

..DIAL/DEAN.. 07/31/2014




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