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    Day 2 Outlook >
Sep 21, 2014 2000 UTC Day 1 Convective Outlook
Updated: Sun Sep 21 19:34:23 UTC 2014 (Print Version | 20140921 2000Z Day 1 shapefile | 20140921 2000Z Day 1 KML)
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 Forecast Discussion
   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.

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z

        
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