Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS01 KWNS 211936
SWODY1
SPC AC 211934

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0234 PM CDT SUN SEP 21 2014

VALID 212000Z - 221200Z

...NO SVR TSTM AREAS FORECAST...

...SUMMARY...
SCATTERED SHOWERS AND A FEW THUNDERSTORMS WITH GUSTS APPROACHING
SEVERE LEVELS ARE EXPECTED FROM THE EASTERN GREAT LAKES ACROSS THE
CENTRAL APPALACHIANS TO THE MID SOUTH. SCATTERED THUNDERSTORMS WITH
ISOLATED STRONG THUNDERSTORM WIND GUSTS ARE ALSO EXPECTED ACROSS
PARTS OF THE SOUTHWEST AND GREAT BASIN THIS AFTERNOON AND EVENING.

...NRN AL...TN...KY...WV...
A COLD FRONT CONTINUES TO SPREAD SEWD ACROSS LOWER MS/OH/TN RIVER
VALLEYS AND INTO THE LOWER GREAT LAKES REGION. HEATING AHEAD OF THIS
FRONT AND STRENGTHENING WIND FIELDS MAY STILL ALLOW FOR ISOLATED
SEVERE WIND GUSTS THIS AFTERNOON BEFORE SUNSET. FOR MORE INFORMATION
SEE MESOSCALE DISCUSSION 1754.

...NV INTO UT...
HEATING IS LEADING TO AN INCREASE IN STORM COVERAGE ACROSS NV INTO
SWRN UT UNDER THE UPPER TROUGH WITH COOL TEMPERATURES ALOFT.
RELATIVELY COOL SURFACE TEMPERATURES EXIST ACROSS NRN AREAS THUS
HAVE SHUNTED THE 5% WIND PROBS FARTHER SWWD. VEERING AND INCREASING
WINDS WITH HEIGHT SHOULD FAVOR A FEW STRONG CELLS CAPABLE OF SMALL
HAIL AND PERHAPS STRONG WIND GUSTS. FOR MORE INFORMATION SEE
MESOSCALE DISCUSSION 1755.

..JEWELL.. 09/21/2014

.PREV DISCUSSION... /ISSUED 1125 AM CDT SUN SEP 21 2014/

...NORTHEAST...
A STRONG SHORTWAVE TROUGH OVER THE GREAT LAKES WILL PIVOT
EAST-NORTHEAST WITH THE GREATEST 500MB HEIGHT FALLS EXPECTED ACROSS
THE ST. LAWRENCE VALLEY AND ADJACENT AREAS OF NY/VT THROUGH TONIGHT.
A BELT OF 60-75KT CYCLONIC MID-LEVEL FLOW WILL TRANSLATE THROUGH THE
EASTERN FLANK OF THE TROUGH...FROM OH...ACROSS THE CENTRAL
APPALACHIANS...AND THEN OVER NORTHERN NEW ENGLAND...THROUGH EARLY
MONDAY. A WEAKER AND WARMER DISTURBANCE EAST OF THE OUTER BANKS IS
FORECAST TO ACCELERATE NORTHWARD AND SKIRT SOUTHEAST NEW ENGLAND
COASTAL WATERS BEFORE BECOMING ABSORBED BY STRONGER WESTERLIES OVER
THE CANADIAN MARITIME PROVINCES LATE TONIGHT.

LATEST INDICATIONS PROVIDE NO COMPELLING EVIDENCE TO INCREASE SEVERE
WEATHER PROBABILITIES AHEAD OF THE GREAT LAKES/OH VALLEY UPPER
TROUGH AND ITS ASSOCIATED STRONG SURFACE COLD FRONT. A LEADING BAND
OF SHOWERS MOVING EAST FROM NORTHEAST NY TO EASTERN WV PANHANDLE
APPEARS TO BE DECAYING AS IT BECOMES REMOVED FROM DEEP-LAYER FORCING
FOR ASCENT TO THE WEST. DESPITE GENERALLY CLEAR SKIES AND SURFACE
HEATING IMMEDIATELY AHEAD OF THIS LEADING CONVECTIVE BAND...LATEST
GUIDANCE AND RADAR TRENDS ACROSS WESTERN PA/NY SUPPORT THE IDEA OF
NEW DEVELOPMENT OCCURRING ALONG THE SURFACE COLD FRONT. THIS
ACTIVITY WILL SPREAD EAST INTO A RELATIVELY STABLE AIRMASS IN THE
WAKE OF THE LEADING BAND OF SHOWERS/CLOUDS. DESPITE STRENGTHENING
DYNAMICS AND THE PRESENCE OF 40KT VERTICAL SHEAR...NEW CONVECTION
WILL LIKELY STRUGGLE GIVEN LACK OF GREATER BUOYANCY. A FEW LINE
SEGMENTS/PERSISTENT STORMS MAY MOVE EAST AT UP TO 40KT AND PRODUCE
MINOR WIND DAMAGE SUCH AS DOWNED LIMBS/TREES BUT GREATER ORGANIZED
SEVERE WEATHER POTENTIAL APPEARS LIMITED.

...DELMARVA/CENTRAL APPALACHIANS SOUTHWEST TO TN VALLEY...
THE TRAILING PORTION OF THE MID/UPPER TROUGH WILL SPREAD SOUTH FROM
THE OH RIVER VALLEY WITH A SMALLER SECONDARY HEIGHT FALL CENTER
FORECAST ACROSS THE SOUTHERN APPALACHIANS/TN VALLEY BY MONDAY
MORNING. WIDELY SCATTERED THUNDERSTORMS SHOULD DEVELOP ALONG/AHEAD
OF THE COLD FRONT AS DIURNAL HEATING CONTRIBUTES TO MODEST
DESTABILIZATION. STRONGER INSTABILITY /SBCAPE AROUND 1500 J PER KG/
IS FORECAST WITH SOUTHWESTWARD EXTENT ALONG THE FRONT BUT THESE
AREAS ALSO BECOME INCREASINGLY REMOVED FROM STRONGER LARGE-SCALE
FORCING AND VERTICAL SHEAR NEEDED FOR MORE PERSISTENT/ORGANIZED
CONVECTION. WHILE STRONGER STORMS WITH SOME POTENTIAL TO PRODUCE
WIND DAMAGE MAY BE REALIZED JUST ABOUT ANYWHERE ALONG THE EXTENSIVE
FRONTAL ZONE...FROM THE CENTRAL APPALACHIANS AND MID-ATLANTIC
SOUTHWEST ACROSS THE TN VALLEY...THE SPORADIC/LIMITED NATURE OF THIS
THREAT DOES NOT APPEAR TO WARRANT HIGHER SEVERE THUNDERSTORM WIND
PROBABILITIES WITH THIS OUTLOOK.

...NV/UT...
THUNDERSTORMS ARE EXPECTED TO CONTINUE ACROSS MUCH OF UT TODAY
AMIDST RELATIVELY DEEP MOISTURE AND BROAD ZONE OF PERSISTENT LIFT ON
THE EASTERN FLANK OF SLOW-MOVING CLOSED LOW OVER NV. ADDITIONAL
DIURNAL STORM DEVELOPMENT MAY OCCUR WITHIN/NEAR THE CYCLONE CENTER
OVER NV WHERE LATEST VISIBLE SATELLITE IMAGERY DEPICTS STRONG
SURFACE HEATING NOW UNDERWAY BENEATH RELATIVELY COLDER TEMPERATURES
ALOFT. POCKETS OF STRONGER UNIDIRECTIONAL DEEP-LAYER SHEAR MAY LEND
SUPPORT FOR A COUPLE OF MORE PERSISTENT FAST-MOVING CELLS/LINES OVER
UT... WHILE A DEEPER MIXED BOUNDARY LAYER OVER NV RESULTS IN AREAS
OF HIGHER DCAPE. BOTH REGIMES COULD SUPPORT ISOLATED DAMAGING GUSTS
THROUGH EARLY EVENING.



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