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    Day 2 Outlook >
Jul 24, 2014 0600 UTC Day 1 Convective Outlook
Updated: Thu Jul 24 05:54:23 UTC 2014 (Print Version | 20140724 1200Z Day 1 shapefile | 20140724 1200Z Day 1 KML)
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 Forecast Discussion
   SPC AC 240554

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1254 AM CDT THU JUL 24 2014

   VALID 241200Z - 251200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTN INTO TONIGHT ACROSS
   PARTS OF EASTERN MONTANA INTO WESTERN AND CENTRAL NORTH
   DAKOTA...PERHAPS PARTS OF ADJACENT NORTHERN SOUTH DAKOTA...

   ...SUMMARY...
   A FEW SEVERE THUNDERSTORMS CAPABLE OF PRODUCING LARGE HAIL AND
   STRONG WIND GUSTS ARE POSSIBLE ACROSS PARTS OF EASTERN MONTANA INTO
   WESTERN AND CENTRAL NORTH DAKOTA THIS AFTERNOON INTO TONIGHT. 
   STRONG STORMS...WITH POTENTIAL FOR LOCALIZED DAMAGING WIND
   GUSTS...MAY ALSO DEVELOP ACROSS PARTS OF THE CENTRAL AND SOUTHERN
   APPALACHIANS INTO THE SOUTHERN MID ATLANTIC COAST STATES TODAY.

   ...SYNOPSIS...
   THE SIGNIFICANT SHORT WAVE TROUGH AND EMBEDDED CLOSED LOW NOW OVER
   THE PACIFIC NORTHWEST APPEAR LIKELY TO CONTINUE SLOWLY INLAND DURING
   THIS FORECAST PERIOD...AS AN UPSTREAM IMPULSE PROGRESSES ACROSS THE
   NORTHEAST PACIFIC...TOWARD THE BRITISH COLUMBIA COAST.  WITH
   SUBTROPICAL RIDGING CURRENTLY PROMINENT ACROSS MUCH OF THE
   INTERMOUNTAIN WEST/ROCKIES AND PLAINS...THE LEAD SYSTEM IS FORECAST
   TO TURN NORTHEASTWARD AROUND ITS CREST...ACROSS THE CANADIAN AND
   NORTHERN U.S. ROCKIES...INTO ALBERTA AND SASKATCHEWAN.  MODELS
   SUGGEST THAT SUBSTANTIVE MID-LEVEL HEIGHT FALLS WILL GENERALLY BE
   CONFINED TO MONTANA AND PORTIONS OF THE DAKOTAS...WITH ONLY MINOR
   WEAKENING OF THE SUBTROPICAL HIGH...ALTHOUGH ITS CENTER MAY SHIFT
   SOUTHEAST OF THE CENTRAL ROCKIES INTO THE SOUTHERN HIGH PLAINS.

   OTHERWISE...LITTLE CHANGE TO THE LARGE-SCALE UPPER PATTERN IS
   EXPECTED...WITH AMPLIFIED TROUGHING PERSISTING EAST OF THE
   MISSISSIPPI VALLEY THROUGH THE ATLANTIC SEABOARD.  THE LEADING EDGE
   OF LOW-LEVEL COOLING/DRYING ASSOCIATED WITH THIS FEATURE IS EXPECTED
   TO ADVANCE SOUTHEAST OF THE OHIO VALLEY INTO THE SOUTH ATLANTIC AND
   GULF COAST STATES.  AT THE SAME TIME...A SOUTHERLY RETURN FLOW WILL
   CONTRIBUTE MOISTENING ACROSS THE CENTRAL INTO NORTHERN
   PLAINS...AHEAD OF THE NORTHWESTERN UPPER TROUGHING.  HOWEVER...THIS
   IS GENERALLY EXPECTED TO OCCUR BENEATH VERY WARM AND CAPPING
   ELEVATED MIXED LAYER AIR ADVECTING NORTHEAST AND EAST OF THE
   NORTHERN AND CENTRAL ROCKIES.

   HIGHEST PROBABILITIES FOR THUNDERSTORMS DURING THIS PERIOD APPEAR TO
   EXIST AHEAD OF THE FRONT...ACROSS THE SOUTHEASTERN U.S...AS WELL AS
   WITHIN A PLUME OF MONSOONAL MOISTURE FROM THE SOUTHERN PLATEAU
   THROUGH THE CENTRAL ROCKIES.  BUT AT LEAST SCATTERED THUNDERSTORM
   ACTIVITY IS EXPECTED WITHIN A LOWER/MID TROPOSPHERIC WARM ADVECTION
   REGIME DEVELOPING NORTHEAST OF THE MID MISSOURI VALLEY...AS WELL AS
   AHEAD OF A COLD FRONT ADVANCING INTO THE WESTERN DAKOTAS BY LATE
   TONIGHT.

   ...NORTHERN AND CENTRAL PLAINS...
   STRONGER MID-LEVEL HEIGHT FALLS ARE NOT EXPECTED TO REACH EASTERN
   MONTANA AND THE WESTERN DAKOTAS UNTIL AT LEAST LATE THIS
   AFTERNOON...PERHAPS THIS EVENING.  AND VERY WARM ELEVATED MIXED
   LAYER AIR PROBABLY WILL SUPPRESS VIGOROUS CONVECTIVE DEVELOPMENT
   WITHIN THE CORRIDOR OF HIGHER BOUNDARY LAYER MOISTURE CONTENT ALONG
   THE PRE-FRONTAL SURFACE TROUGH ACROSS THE REGION.  HOWEVER...THE
   VERY STEEP MID-LEVEL LAPSE RATES ASSOCIATED WITH THIS AIR MASS WILL
   CONTRIBUTE TO SIZABLE CAPE...AND A RATHER BROAD AREA WITH AT LEAST A
   CONDITIONAL RISK FOR SEVERE STORMS.  

   IT CURRENTLY APPEARS THAT...THROUGH MUCH OF THE AFTERNOON
   HOURS...ANY THUNDERSTORM ACTIVITY WILL BE WIDELY SCATTERED IN
   NATURE.  ACTIVITY PROBABLY WILL FORM ACROSS THE HIGHER TERRAIN
   NEAR/WEST OF THE NORTH CENTRAL HIGH PLAINS...IN RESPONSE TO DAYTIME
   HEATING AND OROGRAPHIC FORCING.  BUT ISOLATED/WIDELY SCATTERED STORM
   DEVELOPMENT MAY NOT BE OUT OF THE QUESTION WITHIN A ZONE OF ENHANCED
   LOWER/MID TROPOSPHERIC WARM ADVECTION...NEAR A SOUTHERLY 850 MB
   JET...ON THE EASTERN EDGE OF THE ELEVATED MIXED LAYER AIR ACROSS THE
   EASTERN DAKOTAS INTO MINNESOTA/IOWA.

   OTHERWISE...IT APPEARS POSSIBLE THAT FORCING ALONG/AHEAD OF AN
   EASTWARD ADVANCING COLD FRONT COULD SUPPORT STORM INITIATION ACROSS
   PARTS OF EASTERN MONTANA AS EARLY AS 21-23Z.  ALTHOUGH THE STRONGER
   MID/UPPER FLOW ASSOCIATED WITH THE APPROACHING UPPER TROUGH MAY LAG
   TO THE WEST OF THE FRONT...PRE-FRONTAL VERTICAL SHEAR ACROSS EASTERN
   MONTANA INTO NORTH DAKOTA STILL APPEARS SUFFICIENT FOR ORGANIZED
   CONVECTIVE DEVELOPMENT...INCLUDING SUPERCELLS...GIVEN EXPECTED MIXED
   LAYER CAPE OF 2000-3000+ J/KG. 
   THE EVOLUTION OF A MESOSCALE CONVECTIVE SYSTEM CAPABLE OF PRODUCING
   ONE OR TWO SWATHS OF POTENTIALLY DAMAGING WIND GUSTS SEEMS AT LEAST
   A POSSIBILITY AS UPPER FORCING SPREADS EASTWARD INTO THE NORTHERN
   PLAINS THIS EVENING.

   ...CNTRL/SRN APPALACHIANS INTO SRN MID ATLANTIC COAST REGION...
   WEAK LOWER/MID TROPOSPHERIC LAPSE RATES PROBABLY WILL LIMIT CAPE
   ALONG/AHEAD OF THE SOUTHWARD ADVANCING FRONTAL ZONE TODAY. 
   HOWEVER...IN THE PRESENCE OF SEASONABLY HIGH MOISTURE
   CONTENT...MODEST WESTERLY MID-LEVEL FLOW MAY ENHANCE CONVECTIVE
   DEVELOPMENT...SUPPORTING AT LEAST LOW PROBABILITIES FOR STORMS
   CAPABLE OF PRODUCING POTENTIALLY DAMAGING WIND GUSTS.

   ..KERR/DIAL.. 07/24/2014

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z

        
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