Severe Storm Outlook Narrative (AC)
Issued by NWS

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000
ACUS02 KWNS 290600
SWODY2
SPC AC 290559

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1259 AM CDT WED JUL 29 2015

VALID 301200Z - 311200Z

...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PORTIONS OF THE
SOUTHEAST/MID-ATLANTIC/NORTHEAST STATES...

...SUMMARY...
ISOLATED SEVERE THUNDERSTORMS WILL BE POSSIBLE ACROSS THE NORTHEAST
STATES/NEW ENGLAND...AS WELL AS OTHER PARTS OF THE MID-ATLANTIC AND
SOUTHEAST STATES...THURSDAY AFTERNOON AND EARLY EVENING.

...SYNOPSIS...
A SEMI-AMPLIFIED/PROGRESSIVE LARGE-SCALE PATTERN WILL EXIST OVER THE
CONUS ON THURSDAY. AS 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 THROUGH EARLY FRIDAY.

...NORTHEAST STATES/NEW ENGLAND...
ON THE SOUTHERN PERIPHERY OF THE LARGE-SCALE TROUGH OVER NORTHERN
ONTARIO/HUDSON BAY...WEAK TO MODERATE HEIGHT FALLS ARE EXPECTED AS A
LEAD SHORTWAVE TROUGH/MID-LEVEL SPEED MAX CROSSES THE REGION
THURSDAY AFTERNOON/NIGHT. EARLY-DAY CLOUD COVER/WIDELY SCATTERED
PRECIPITATION WILL LIKELY PRECEDE THE EASTWARD-ADVANCING COLD
FRONT...BUT POCKETS OF STRONGER HEATING AND RELATED WEAK TO MODERATE
BUOYANCY SHOULD ALLOW FOR AT LEAST SOME SEVERE THUNDERSTORMS TO
DEVELOP THURSDAY AFTERNOON IN AREAS SPANNING EASTERN PA/NJ INTO
EASTERN NY AND NEW ENGLAND. WHERE SUFFICIENT DESTABILIZATION
OCCURS...ADEQUATE VERTICAL SHEAR DURING THE DAY /30-35 KT WITH
STRONGER SHEAR ARRIVING AT NIGHT/ WILL SUPPORT SEMI-ORGANIZED STORM
MODES INCLUDING MULTICELLS AND LINE SEGMENTS CAPABLE OF PRIMARILY A
DAMAGING-WIND RISK. PORTIONS OF EASTERN NY AND NEW ENGLAND WILL BE
REEVALUATED IN SUBSEQUENT OUTLOOKS FOR THE POSSIBILITY A CATEGORICAL
SLIGHT RISK UPGRADE.

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

...UPPER MIDWEST/LAKE SUPERIOR VICINITY...
AS A SHORTWAVE TROUGH MODESTLY AMPLIFIES/SPREADS SOUTHEASTWARD OVER
THE REGION...A FEW THUNDERSTORMS COULD DEVELOP WITHIN A MARGINALLY
MOIST/WEAKLY CAPPED BOUNDARY LAYER ACROSS THE REGION. WHILE SEVERE
POTENTIAL SHOULD BE NEGLIGIBLE...CONVECTIVELY ENHANCED GUSTY WINDS
MAY BE POSSIBLE COINCIDENT WITH A WELL-MIXED BOUNDARY LAYER AND
RELATIVELY STRONG DEEP-LAYER NORTHWESTERLY WINDS.

...SOUTH-CENTRAL HIGH PLAINS TO LOWER CO RIVER VALLEY...
ON THE IMMEDIATE PERIPHERY OF THE UPPER RIDGE...A FEW STRONGER
STORMS /WIND AS MAIN POTENTIAL ASIDE FROM LOCALLY HEAVY RAIN/ MAY
OCCUR THURSDAY AFTERNOON/EARLY EVENING ACROSS THE SOUTH-CENTRAL HIGH
PLAINS INCLUDING PARTS OF NORTHEAST NM INTO SOUTHWEST KS AND TX/OK
PANHANDLES...AND POSSIBLY SOUTHERN AZ/LOWER CO RIVER VALLEY.
HOWEVER...SEVERE PROBABILITIES CURRENTLY APPEAR TOO MARGINAL GIVEN
GENERAL EXPECTATIONS OF WEAK MID-LEVEL LAPSE RATES AND/OR WEAK
VERTICAL SHEAR.

..GUYER.. 07/29/2015




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