Mar 28, 2009 1300 UTC Day 1 Convective Outlook
Updated: Sat Mar 28 12:35:15 UTC 2009
Probabilistic to Categorical Outlook Conversion Table (Effective Feb 14, 2006).
Categorical Graphic
20090328 1300 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20090328 1300 UTC Day 1 Tornado Probabilities Graphic
Torndao Legend Image
Probabilistic Damaging Wind Graphic
20090328 1300 UTC Day 1 Damaging Wind Probabilities Graphic
Wind Legend Image
Probabilistic Large Hail Graphic
20090328 1300 UTC Day 1 Large Hail Probabilities Graphic
Hail Legend Image
   SPC AC 281230
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0730 AM CDT SAT MAR 28 2009
   
   VALID 281300Z - 291200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS A LARGE PORTION OF THE
   OH/TN VLYS INTO THE SERN STATES...
   
   ...SYNOPSIS...
   INTENSE UPPER LEVEL LOW WHICH HAS BEEN SLOW TO MOVE OVER OK UP TO
   NOW WILL BEGIN TO EVOLVE INTO AN OPEN-WAVE AND EJECT RAPIDLY NEWD
   THROUGH TONIGHT INTO THE OH VALLEY.  AS THIS OCCURS...SURFACE COLD
   FRONT WILL SURGE E-SEWD AND EXTEND ALONG THE CENTRAL APPALACHIANS
   INTO THE NERN GULF OF MEXICO BY THE END OF THE PERIOD.  LARGE AREA
   OF ENHANCED MID AND UPPER LEVEL SSWLY WINDS ASSOCIATED WITH THIS
   SYSTEM WILL MAINTAIN ENHANCED DEEP LAYER SHEAR ACROSS NEARLY ALL OF
   THE SERN 1/4 OF THE CONUS.
   
   EXTENSIVE DEEP MOIST CONVECTION HAS BEEN PERSISTENT ALONG THE
   CENTRAL AND NERN GULF COAST REGION OVER THE PAST 24 HRS...WHICH HAS
   INHIBITED GULF MOISTURE RETURN AWAY FROM THE IMMEDIATE COAST THROUGH
   THE EARLY MORNING HOURS.  HOWEVER...SSWLY LLJ IN EXCESS OF 60 KT
   EVIDENT ON MORNING VWP/S OVER THE NERN GULF COAST REGION WILL
   TRANSLATE ENEWD ACROSS MORE OF THE SOUTHEASTERN STATES TODAY.  THIS
   SHOULD ALLOW EFFECTIVE WARM FRONT TO LIFT NWD/BECOME BETTER DEFINED
   FROM PORTIONS OF THE CENTRAL CAROLINAS INTO SRN/CENTRAL GA. 
   LOCATION OF THIS FRONT/INSTABILITY GRADIENT WILL BE PARAMOUNT IN
   PINNING DOWN CORRIDOR OF MOST INTENSE SEVERE THREAT TODAY.  IN
   ADDITION...INTENSE DEEP ASCENT AND STRONG HEIGHT FALLS ALOFT WILL
   ROTATE AROUND MAIN UPPER SYSTEM AND SUPPORT CONTINUED THREAT OF
   STRONG TO SEVERE THUNDERSTORMS AHEAD OF MAIN SURFACE COLD FRONT FROM
   THE MID SOUTH INTO THE TN/OH RIVER VALLEYS.  THIS THREAT MAY EVOLVE
   IN THE FORM OF SUBSEQUENT BANDS OF MOIST CONVECTION WITH EACH BAND
   RACING NNEWD THROUGH THE PERIOD.  IT REMAINS POSSIBLE THAT PORTIONS
   OF THE SRN APPALACHIANS MAY SEE A RELATIVE MINIMUM IN SEVERE
   THUNDERSTORMS AS COMPARED TO REGIONS TO THE NNW AND SSE.
   
   ...CENTRAL/NERN GULF COAST INTO THE SOUTHEAST/MID ATLANTIC...
   AREAS OF STRONG TO SEVERE THUNDERSTORMS HAVE BEEN PERSISTENT FROM
   THE MOUTH OF THE MS RIVER ACROSS SRN AL/FL PANHANDLE DURING THE
   EARLY MORNING AHEAD OF MAIN COLD FRONT.  STRONG SLY LOW LEVEL FLOW 
   AND AFOREMENTIONED SURFACE FRONT/INSTABILITY GRADIENT HAS LIFTED NWD
   PRECEEDING THIS ACTIVITY...ALLOWING INFLUX OF RICHER MOISTURE TO
   SPREAD INTO SWRN GA THROUGH 12Z.  THIS TREND SHOULD PERSIST TODAY
   AND ALLOW AREA OF MARGINAL TO MODERATE MLCAPE TO EVOLVE FROM THE FL
   PANHANDLE INTO SRN GA/ERN CAROLINAS THROUGH THE DAY.  EITHER
   THUNDERSTORMS WILL ORGANIZE/EVOLVE INTO A MORE COHERENT MCS AND LIFT
   ENEWD ACROSS THIS REGION TODAY...OR SERIAL SMALLER-SCALE
   SUPERCELLS/BOW ECHOES WILL CONTINUE TO EVOLVE OFF THE GULF AND/OR
   NEAR THE FRONT AND IMPACT THE REGION AS THEY RACE NEWD.  EITHER CASE
   SUGGESTS THIS ZONE COULD BE QUITE ACTIVE WITH A MYRIAD OF SEVERE
   THREATS...AT LEAST THROUGH THE EARLY EVENING.  NNEWD EXTENT OF
   SEVERE THREAT SHOULD BE TEMPERED AFTER DARK...HOWEVER AT LEAST
   ISOLATED SEVERE COULD ACCOMPANY STORMS INTO PORTIONS OF THE MID
   ATLANTIC DURING LATTER HALF OF PERIOD.
   
   ...MID SOUTH INTO THE TN/OH VLYS...
   A SEPARATE AREA OF SVR POTENTIAL WILL LIKELY DEVELOP ACROSS PORTIONS
   OF THE TN/OH VLYS DURING THE AFTN/EVE...WITH ONGOING STRONG TO
   MARGINALLY SEVERE STORMS FROM NERN AR INTO SRN MO.  STRONGEST DCVA
   WILL TRANSLATE NEWD AWAY FROM THE RICH GULF MOISTURE SOURCE FARTHER
   SE.  BUT...LINGERING 50S SFC DEW POINTS ARCING BACK ALONG THE
   CDFNT/SFC LOW INTO THE LWR OH VLY BENEATH STEEP MID-TROPOSPHERIC
   LAPSE RATES WILL CONTRIBUTE TO MLCAPES OF A FEW HUNDRED J PER KG. 
   MODELS CONTINUE TO SUPPORT SCATTERED TSTM DEVELOPMENT AHEAD OF THE
   COLD FRONT THROUGH THE DAY AMIDST STRONG VERTICAL SHEAR....INCLUDING
   A FEW LOW-TOPPED SUPERCELLS.  LARGE HAIL AND ISOLD DMGG WIND GUSTS
   WILL BE POSSIBLE.  TORNADOES CANNOT BE RULED OUT...ALTHOUGH FORECAST
   SOUNDINGS INDICATE MUCH OF THIS ACTIVITY COULD REMAIN ELEVATED.  SVR
   THREATS WILL DIMINISH WITH NE EXTENT AND AFTER SUNSET.
   
   ..EVANS/GARNER.. 03/28/2009
   
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