Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS02 KWNS 241738
SWODY2
SPC AC 241737

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1237 PM CDT SUN JUL 24 2016

VALID 251200Z - 261200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS NORTHEAST PA...FAR
NORTHERN NJ THROUGH PORTIONS OF EASTERN NY TO WESTERN NEW
ENGLAND....

...THERE IS A MRGL RISK OF SVR TSTMS EXTENDING FROM THE NORTHEAST
STATES THROUGH THE OH VALLEY...

...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF THE CENTRAL AND
NORTHERN HIGH PLAINS...

...SUMMARY...
ISOLATED TO SCATTERED SEVERE STORMS ARE EXPECTED ACROSS PORTIONS OF
THE NORTHEAST UNITED STATES MONDAY AFTERNOON AND EVENING...WHILE
ISOLATED STRONG TO SEVERE STORMS WILL BE POSSIBLE FROM THE CENTRAL
HIGH PLAINS TO THE NORTHERN GREAT PLAINS MONDAY AFTERNOON TO MONDAY
NIGHT.

...SYNOPSIS...
A SHORTWAVE TROUGH MOVING THROUGH NORTHERN ONTARIO TODAY WILL
PROCEED EAST ACROSS SOUTHERN QUEBEC DURING DAY 2...WHILE A MIDLEVEL
IMPULSE TRANSLATING THROUGH THE BASE OF THE QUEBEC TROUGH WILL
RESULT IN 30-60-METER 12-HOUR 500-MB HEIGHT FALLS THROUGH MONDAY
AFTERNOON AND NIGHT ACROSS THE NORTHEAST STATES.  A COLD FRONT
ATTENDANT TO THE SOUTHEAST CANADA TROUGH IS EXPECTED TO ADVANCE EAST
THROUGH THE LOWER GREAT LAKES REGION TO NEW ENGLAND...WHILE THE
TRAILING PORTION MOVES SOUTH THROUGH THE OH VALLEY AND INTO AR AND
OK.

MEANWHILE...A MID-UPPER LEVEL ANTICYCLONE WILL REMAIN LOCATED OVER
THE FOUR CORNERS STATES.  NEUTRAL HEIGHT CHANGES ARE EXPECTED ACROSS
THE NORTH-CENTRAL HIGH PLAINS TO THE DAKOTAS INTO MONDAY AFTERNOON
FOLLOWED BY A WEAK MIDLEVEL IMPULSE WITHIN MODEST WESTERLY FLOW
ALOFT EXPECTED TO REACH THE DAKOTAS MONDAY NIGHT.

...NORTHEAST STATES...
MOISTENING OF THE PRE-FRONTAL AIR MASS PER SOUTHWESTERLY LOW-LEVEL
WINDS IS EXPECTED TO PERSIST FROM DAY 1 INTO DAY 2 ACROSS PA/NY...
WITH MOISTURE SPREADING INTO THE HUDSON VALLEY AND MUCH OF WESTERN
AND SOUTHERN NEW ENGLAND BY MONDAY AFTERNOON.  PRECIPITABLE WATER
VALUES EXCEEDING 1.5 INCHES ARE EXPECTED ACROSS THE FULL EXTENT OF
THE WARM SECTOR AND SURFACE DEW POINTS IN THE UPPER 60S TO NEAR 70 F
REACH THE SLIGHT RISK AREA MONDAY AFTERNOON.  THE EASTERN EXTENT OF
AN EML /700-500-MB LAPSE RATES OF 6.5-7 C PER KM/ IS EXPECTED TO
SPREAD EAST ATOP THE MOISTENING AND AS THE COLD FRONT MOVES THROUGH
CENTRAL TO EASTERN NY AND NORTHEAST PA BETWEEN 21-00Z. ALTHOUGH
MODELS CONTINUE TO SUGGEST SOME EARLY PERIOD CONVECTION/ CLOUDINESS
COULD LIMIT THE DEGREE OF SURFACE HEATING AND OVERALL
DESTABILIZATION...MUCAPE OF AT LEAST 1000 J/KG IS EXPECTED INTO THE
SLIGHT RISK AREA.  THIS COMBINED WITH THE FORECAST OF FORCING
ATTENDANT TO THE SHORTWAVE TROUGH AND STRENGTHENING DEEP-LAYER SHEAR
/UP TO 40 KT/ ACROSS NY/NORTHERN PA TO NEW ENGLAND MONDAY AFTERNOON
AND EVENING HAS RESULTED IN GREATER CONFIDENCE FOR HIGHER SEVERE
PROBABILITIES...ESPECIALLY ACROSS NORTHEAST PA TO WESTERN NEW
ENGLAND.  STRENGTHENING WESTERLY WINDS WITH HEIGHT SUGGEST ORGANIZED
STORMS WILL BE POSSIBLE...AND SOME SPLITTING STORMS.  DAMAGING WINDS
WILL BE THE PRIMARY THREAT.  THE MARGINAL RISK HAS ALSO BEEN
EXPANDED INTO MORE OF MAINE...GIVEN THE PRESENCE OF STRONGER FORCING
FOR ASCENT INTO THAT AREA.

...OH VALLEY...
STRONG INSTABILITY WILL SUPPORT THUNDERSTORM DEVELOPMENT INTO MONDAY
AFTERNOON AND EVENING AS THE COLD FRONT ADVANCES TO THE SOUTH.
ORGANIZED SEVERE STORMS SHOULD BE LIMITED IN COVERAGE DUE TO THE
LACK OF STRONGER BULK SHEAR.

...CNTRL/NRN HIGH PLAINS...
MODEST MOISTURE ADVECTION WILL OCCUR INTO THE NORTHERN HIGH PLAINS
WITH SURFACE DEW POINTS IN THE UPPER 50S TO AROUND 60 F NOT EXPECTED
TO REACH WESTERN NEB TO THE WESTERN DAKOTAS UNTIL AFTER 26/00Z.
S-SELY SFC WINDS WILL BECOME ESTABLISHED E OF A LEE TROUGH...AND
COULD SUPPORT THE DEVELOPMENT OF ISOLATED TSTMS WITHIN AN UPSLOPE
REGIME ACROSS THE BLACK HILLS AND PERHAPS OVER THE FRONT RANGE.
MODELS DIFFER IN THE COVERAGE AND OCCURRENCE OF MONDAY AFTERNOON
STORM DEVELOPMENT...WITH GREATER CONFIDENCE IN STORMS MONDAY NIGHT
AS A SOUTHERLY LOW-LEVEL JET STRENGTHENS INTO THIS REGION.
VERTICALLY VEERING WINDS WITH MODEST WESTERLY MIDLEVEL WINDS SHOULD
SUPPORT SUPERCELLS WITH ANY AFTERNOON STORMS THAT CAN DEVELOP
PRODUCING LARGE HAIL AND DAMAGING WINDS.  GIVEN UNCERTAINTY IN STORM
COVERAGE AND INTENSITIES...THIS OUTLOOK WILL MAINTAIN A MARGINAL
SEVERE RISK.

..PETERS.. 07/24/2016

$$


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