Categorical Graphic
Probabilistic Tornado Graphic
Probabilistic Damaging Wind Graphic
Probabilistic Large Hail Graphic

   SPC AC 280552
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1252 AM CDT SAT JUN 28 2008
   
   VALID 281200Z - 291200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS SRN HIGH PLAINS TO INLAND
   PORTIONS MID-ATLANTIC STATES...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS UPPER MS VALLEY
   REGION...
   
   ...SYNOPSIS...
   DOMINANT UPPER AIR FEATURE FOR THIS PERIOD WILL BE STG RIDGING THAT
   WILL CONTINUE OVER GREAT BASIN REGION AND NWD OVER WRN CANADA. 
   DOWNSTREAM MID/UPPER LOW -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY
   OVER ND -- IS FCST TO PIVOT EWD ACROSS MN EARLY IN PERIOD THEN ENEWD
   OVER UPPER GREAT LAKES BY 29/12Z.  CONSIDERABLE SPREAD STILL IS
   EVIDENT AMONGST SREF MEMBERS AND LATEST/28/00Z OPERATIONAL PACKAGES
   WITH TRACK OF PRIMARY CYCLONE CENTER...PARTICULARLY AFTER ABOUT
   29/00Z.  IN ANY EVENT...HOWEVER...ASSOCIATED SFC COLD FRONT IS FCST
   TO CONTINUE MOVING SWD ACROSS CENTRAL/SRN PLAINS AND EWD/SEWD OVER
   GREAT LAKES AND OH VALLEY REGIONS...REACHING TO NEAR WRN
   OH...OZARKS...CENTRAL OR SRN OK...AND TX PANHANDLE BY 29/00Z. 
   EFFECTIVE BAROCLINIC BOUNDARY MAY BE SHUNTED FARTHER S AND SE ON
   MESOSCALE BY OUTFLOWS FROM PRIOR MCS ACTIVITY.  BROAD/DIFFUSE WARM
   FRONTAL ZONE IS FCST TO LIFT NWD FROM SRN ONT AND NWRN NY INTO SRN
   QUE.
   
   ELSEWHERE...MOISTURE CHANNEL IMAGERY AND PROFILER DATA INDICATE
   UPPER CYCLONE CENTERED OVER SERN NM...WHOSE CENTER SHOULD DRIFT
   ERRATICALLY ACROSS THAT REGION THROUGH PERIOD.  ASSOCIATED LARGE
   SCALE DESTABILIZATION ALOFT WILL SUPPORT GEN THUNDER POTENTIAL OVER
   REGION.  BROAD/WEAK CYCLONIC GYRE NOW INDICATED W OF NRN BAJA IS
   EXPECTED TO LIFT NWD AND EVOLVE INTO OPEN-WAVE TROUGH...WITH
   ASSOCIATED SHORTWAVE LIFTING NWD ACROSS COASTAL CA AND ADJACENT
   WATERS.
   
   ...ERN GREAT LAKES TO SRN HIGH PLAINS...
   MCS ACTIVITY MAY BE ONGOING AT START OF PERIOD OVER PORTIONS OZARK
   REGION WWD ACROSS SRN KS/NRN OK.  ALTHOUGH BOUNDARY LAYER
   INSTABILITY TRENDS WILL BE DOWNWARD DURING THIS TIME...MOST INTENSE
   CONVECTION STILL MAY BE CAPABLE OF PRODUCING DAMAGING WIND AND MRGL
   SVR HAIL...GREATEST THREAT  FOR SVR GUSTS BEING INVOF BOW/LEWP
   CONFIGURATIONS.  REF LATEST WWS AND MESOSCALE DISCUSSIONS FOR
   DETAILS ON THIS EVOLVING POTENTIAL DURING PRE-DAWN HOURS.
   
   LATER TODAY...SEVERAL BANDS OR CLUSTERS OF SCATTERED TSTMS ARE
   EXPECTED TO DEVELOP -- MAINLY DURING AFTERNOON AND EARLY EVENING
   INVOF SFC BAROCLINIC ZONE.  THIS MAY OCCUR VIRTUALLY ANYWHERE WITHIN
   LONG OUTLOOK CORRIDOR...AND WILL DEPEND STRONGLY ON BOUNDARY
   INFLUENCES FROM MCS ACTIVITY OCCURRING BETWEEN NOW AND THEN.  IN
   GENERAL...LAPSE RATES AND BUOYANCY SHOULD INCREASE WITH WWD EXTENT
   ACROSS OUTLOOK AREA IN PROXIMITY TO ELEVATED MIXED LAYER AIR...AND
   MID-UPPER LEVEL WINDS WILL INCREASE WITH NEWD EXTENT...IN CLOSER
   PROXIMITY TO GREAT LAKES SYSTEM.
   
   POTENTIAL CONCENTRATIONS MAY INCLUDE...
   1. MID-ATLANTIC REGION...DOWNSTREAM FROM ONGOING OH VALLEY
   ACTIVITY...WHERE DIURNAL HEATING OF MOIST BOUNDARY LAYER WILL YIELD
   FAVORABLE DESTABILIZATION.  MAIN UNCERTAINTIES REVOLVE AROUND
   EFFECTS OF CLOUD COVER FROM OH VALLEY MCS...WEAKNESS OF LOW LEVEL
   FORCING WITH STG WLY WIND COMPONENT PROGGED ON BOTH SIDES OF
   FRONT...AND STRENGTH OF SUPPORTIVE ASCENT/SHEAR THAT MAY EXIST E-S
   OF ANY MCV PRODUCED BY THAT MCS.
   2. OK TO LOWER MS VALLEY...WHERE BAND OF SFC DEW POINTS 70S F WILL
   CONTRIBUTE TO MLCAPES 3000-5000J/KG AND CONVERGENCE IS EXPECTED
   ALONG FRONTAL/OUTFLOW BOUNDARIES.  WEAK LOW-MIDLEVEL WINDS WILL
   LIMIT VERTICAL SHEAR SIGNIFICANTLY...DESPITE STG DIRECTIONAL TURNING
   WITH HEIGHT ALONG FRONT...AND ALSO MAY MITIGATE
   LONGEVITY/ORGANIZATION OF SVR MULTICELLULAR CLUSTERS.
   
   AS MESOSCALE UNCERTAINTIES BECOME BETTER RESOLVED...ONE OR TWO
   CORRIDORS OF GREATER WIND/HAIL PROBABILITIES MAY BE NEEDED WITHIN
   CURRENTLY BROAD-BRUSHED 15 PERCENT SWATH.
   
   ...UPPER MS VALLEY REGION...
   SCATTERED TSTMS ARE EXPECTED TO DEVELOP AS EARLY AS MID-LATE MORNING
   OVER PORTIONS MN/IA AND MOVE/EXPAND ESEWD ACROSS PORTIONS WI/IL
   DURING AFTERNOON.  LOW-MIDLEVEL LAPSE RATES ARE FCST TO STEEPEN
   FAVORABLY THROUGHOUT LATE MORNING INTO AFTERNOON HOURS ACROSS THIS
   REGION.  WEAKENING SBCINH WILL PROMOTE INITIATION EVEN THOUGH
   CONVERGENCE SHOULD BE WEAK IN ABSENCE OF SIGNIFICANT BOUNDARIES
   BEHIND SFC FRONT.  MLCAPES 500-1000 J/KG ARE POSSIBLE...RELATED TO
   RESIDUAL MOISTURE...E.G. SFC DEW POINTS 50S TO LOW 60S F...AND SFC
   DIABATIC HEATING...BENEATH MIDLEVEL UVV/COOLING THAT PRECEDES
   PROGRESSIVE UPPER LOW.  DEEP-LAYER SHEAR WILL INCREASE WITH SW
   EXTENT ACROSS CONVECTIVE AREA AND WILL CONTRIBUTE TO POTENTIAL FOR
   SVR HAIL/GUSTS.  SVR POTENTIAL SHOULD DIMINISH SUBSTANTIALLY AFTER
   DARK WHEN SFC DIABATIC COOLING AND CAA REDUCE BOUNDARY LAYER
   INSTABILITY.
   
   ...PORTIONS NWRN CA...SWRN ORE...
   WIDELY SCATTERED TSTMS SHOULD DEVELOP THIS AFTERNOON...INITIALLY ON
   STRONGLY HEATED AREAS OF HIGHER TERRAIN.  DEEP-LAYER LAPSE RATES
   WILL BE AUGMENTED BY WEAK DESTABILIZATION/ASCENT ALOFT...AHEAD OF
   PACIFIC SHORTWAVE TROUGH...AS UPPER RIDGE SHIFTS NWD.  LOW LEVEL
   MOISTURE THAT IS CONTRIBUTING TO 50S F SFC DEW POINTS -- NOW
   OBSERVED IN LOWER ELEVATION IN THIS REGION -- WILL HELP TO BOOST
   MLCAPES TO NEAR 1000 J/KG BY MID-LATE AFTERNOON...WHICH IS UNUSUALLY
   LARGE FOR THIS AREA.  DEEPLY MIXED SUBCLOUD LAYERS MAY SUPPORT
   LOCALIZED POTENTIAL FOR HAIL AND STG-SVR GUSTS TO REACH SFC WITH
   MOST INTENSE CELLS.
   
   ..EDWARDS/GRAMS.. 06/28/2008
   
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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z