Apr 15, 2011 0600 UTC Day 1 Convective Outlook
Updated: Fri Apr 15 10:44:44 UTC 2011
Probabilistic to Categorical Outlook Conversion Table
Public Severe Weather Outlook

The SPC is forecasting ...severe thunderstorms expected over parts of the south today through tonight....   Please read the latest public statement about this event.

Categorical Graphic
20110415 1200 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20110415 1200 UTC Day 1 Tornado Probabilities Graphic
Torndao Legend Image
Probabilistic Damaging Wind Graphic
20110415 1200 UTC Day 1 Damaging Wind Probabilities Graphic
Wind Legend Image
Probabilistic Large Hail Graphic
20110415 1200 UTC Day 1 Large Hail Probabilities Graphic
Hail Legend Image
   SPC AC 150552
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1252 AM CDT FRI APR 15 2011
   
   VALID 151200Z - 161200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS OVER PORTIONS OF MS AND AL...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER A LARGE PORTION OF THE
   SERN STATES...TN AND OH VALLEYS...
   
   ...SYNOPSIS...
   
   UPPER TROUGH CURRENTLY OVER THE CNTRL PLAINS WILL ADVANCE THROUGH
   THE MIDDLE AND LOWER MS VALLEYS FRIDAY...REACHING THE TN AND OH
   VALLEYS FRIDAY NIGHT. ATTENDANT SURFACE LOW WILL OCCLUDE OVER NRN MO
   WHILE OCCLUDED/COLD FRONT ADVANCES EWD THROUGH THE MID-LOWER MS
   VALLEYS. THIS BOUNDARY WILL LIKELY EXTEND FROM THE OH VALLEY INTO
   THE SRN APPALACHIANS AND THE SERN STATES BY THE END OF THE PERIOD.
   WARM FRONT WILL LIFT NWD THROUGH THE CNTRL GULF COAST STATES AND TN
   VALLEY DURING THE DAY.
   
   ...SERN STATES...
   
   SLY TRAJECTORIES EAST OF THE OCCLUDED LOW WILL ADVECT RICHER GULF
   MOISTURE WITH MID 60S DEWPOINTS NWD THROUGH THE LOWER MS VALLEY AND
   PORTIONS OF SERN STATES WARM SECTOR. THIS WILL CONTRIBUTE TO
   MODERATE INSTABILITY AS BOUNDARY LAYER WARMS WITH MLCAPE FROM 1500
   TO 2000 J/KG POSSIBLE FROM PARTS OF MS INTO CNTRL/SRN AL. POTENTIAL
   COMPLICATING FACTOR IS LIKELIHOOD OF ONGOING STORMS FROM WRN TN
   VALLEY INTO THE LOWER MS VALLEY EARLY FRIDAY. CURRENT THINKING IS
   THAT STORMS MAY REINTENSIFY ALONG SRN END OF MCS AND NEW STORMS WILL
   ALSO LIKELY REDEVELOP ALONG RESIDUAL OUTFLOW BOUNDARIES ACROSS MS
   AND AL AS THE ATMOSPHERE DESTABILIZES.
   
   STRONGER LLJ WILL SHIFT NWD THROUGH THE TN AND OH VALLEYS EARLY
   FRIDAY IN ASSOCIATION WITH NEWD EJECTING LEAD VORT LOBE.
   HOWEVER...LLJ MAY STRENGTHEN FARTHER SOUTH ACROSS MS/AL WITHIN EXIT
   REGION OF UPPER JET THAT WILL ROTATE THROUGH BASE OF UPPER
   TROUGH...MAINTAINING LARGE HODOGRAPHS IN WARM SECTOR AND NEAR
   RETREATING WARM FRONT. POTENTIAL EXISTS FOR BOTH SUPERCELL AND
   BOWING STRUCTURES AS STORMS REINTENSIFY DURING THE DAY. THREAT WILL
   EXIST FOR TORNADOES...LARGE HAIL AND DAMAGING WIND WITH GREATEST
   THREAT OF STRONG TORNADOES EXPECTED IN MODERATE RISK AREA. ACTIVITY
   WILL SHIFT EWD THROUGH SRN PARTS OF THE GULF COASTAL STATES
   OVERNIGHT WITH A CONTINUED SEVERE THREAT.
   
   
   ...TN THROUGH MID MS AND OH VALLEYS...
   
   PARTIAL CLEARING IS EXPECTED FROM WRN TN...ERN MO INTO SRN AND CNTRL
   IL IN WAKE OF EARLY CONVECTION ASSOCIATED WITH LEAD VORT MAX.
   DIABATIC WARMING AND NWD ADVECTION OF UPPER 50S TO NEAR 60F
   DEWPOINTS BENEATH COLD AIR ALOFT AND STEEP MID LEVEL LAPSE RATES
   WILL CONTRIBUTE TO A RELATIVELY NARROW CORRIDOR OF MODERATE
   INSTABILITY. DEEPER FORCING FOR ASCENT WITHIN DIVERGENT EXIT REGION
   OF JET MAX ROTATING THROUGH UPPER TROUGH BASE WILL PROMOTE STORMS
   REDEVELOPING ALONG EWD ADVANCING COLD/OCCLUDED FRONT FROM WRN TN NWD
   THROUGH ERN MO AND IL DURING THE AFTERNOON. STRONG VERTICAL SHEAR
   PROFILES WILL SUPPORT SUPERCELLS WITH VERY LARGE HAIL AND ISOLATED
   TORNADOES POSSIBLE. ACTIVITY WILL SHIFT EWD THROUGH PORTIONS OF THE
   TN AND OH VALLEYS BEFORE WEAKENING DURING THE EVENING AS THE
   BOUNDARY LAYER STABILIZES.
   
   ..DIAL/COHEN.. 04/15/2011
   
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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z