Severe Storm Outlook Narrative (AC)
Issued by NWS

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000
ACUS03 KWNS 280720
SWODY3
SPC AC 280719

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0219 AM CDT TUE JUL 28 2015

VALID 301200Z - 311200Z

...THERE IS A MRGL RISK OF SVR TSTMS FROM THE SOUTHEAST
STATES/APPALACHIANS TO NORTHEAST STATES/NEW ENGLAND...

...SUMMARY...
SOME STRONG TO SEVERE THUNDERSTORMS WILL BE POSSIBLE ACROSS A BROAD
PART OF THE EASTERN UNITED STATES THURSDAY AFTERNOON AND EARLY
EVENING.

...SYNOPSIS...
A SEMI-AMPLIFIED/PROGRESSIVE LARGE-SCALE PATTERN WILL EXIST OVER THE
CONUS ON THURSDAY. WHILE AN UPPER RIDGE SHIFTS WESTWARD TOWARD THE
FOUR CORNERS AREA...UPPER-LEVEL TROUGH AMPLIFICATION WILL OCCUR OVER
EASTERN CANADA AND THE LOWER GREAT LAKES/NORTHEAST STATES...WITH A
COLD FRONT ADVANCING EAST-SOUTHEASTWARD ACROSS THE APPALACHIANS AND
MUCH OF THE NORTHEAST/MID-ATLANTIC STATES.

...NORTHEAST STATES/NEW ENGLAND...
ON THE SOUTHERN PERIPHERY OF THE LARGE-SCALE TROUGH OVER NORTHERN
ONTARIO/HUDSON BAY...AT LEAST WEAK HEIGHT FALLS ARE EXPECTED AS A
LEAD SHORTWAVE TROUGH/MID-LEVEL SPEED MAX CROSSES THE REGION
THURSDAY AFTERNOON/NIGHT. EARLY-DAY CLOUD COVER/PRECIPITATION WILL
LIKELY PRECEDE THE EASTWARD-ADVANCING COLD FRONT...BUT POCKETS OF
STRONGER HEATING AND RELATED WEAK TO MODERATE BUOYANCY SHOULD ALLOW
SOME STRONGER/POSSIBLY SEVERE THUNDERSTORMS TO DEVELOP THURSDAY
AFTERNOON IN AREAS SPANNING EASTERN PA/NJ INTO EASTERN NY AND
WESTERN/NORTHERN NEW ENGLAND. PROVIDED SUFFICIENT DESTABILIZATION
OCCURS...MORE THAN ADEQUATE VERTICAL SHEAR /30-40 KT/ WILL SUPPORT
SEMI-ORGANIZED STORM MODES INCLUDING MULTICELLS/LINE SEGMENTS
CAPABLE OF PRIMARILY A DAMAGING-WIND RISK.

...MID-ATLANTIC STATES/SOUTHERN APPALACHIANS TO SOUTHEAST STATES...
WHILE LARGE-SCALE FORCING FOR ASCENT/VERTICAL SHEAR WILL GENERALLY
BE WEAK...A FEW CONVECTIVELY RELATED DISTURBANCES/MODESTLY ENHANCED
NORTHERLY MID-LEVEL WINDS MAY OVERSPREAD THE SOUTHERN
APPALACHIANS/SOUTHEAST STATES ON THURSDAY. THESE FACTORS MAY FURTHER
CONTRIBUTE TO DOWNBURST/LOCALIZED WIND DAMAGE POTENTIAL AS LOW-LEVEL
LAPSE RATES STEEPEN THURSDAY AFTERNOON.

..GUYER.. 07/28/2015




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