Mar 12, 2012 1300 UTC Day 1 Convective Outlook
Updated: Mon Mar 12 12:57:25 UTC 2012
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20120312 1300 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20120312 1300 UTC Day 1 Tornado Probabilities Graphic
Probability of a tornado within 25 miles of a point.
Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point.
Probabilistic Damaging Wind Graphic
20120312 1300 UTC Day 1 Damaging Wind Probabilities Graphic
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point.
Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Probabilistic Large Hail Graphic
20120312 1300 UTC Day 1 Large Hail Probabilities Graphic
Probability of hail 1" or larger within 25 miles of a point.
Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
   SPC AC 121254
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0754 AM CDT MON MAR 12 2012
   
   VALID 121300Z - 131200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF LWR MI AND
   ADJACENT PARTS OF THE MIDWEST...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE LWR MS AND
   LWR TN VLYS...
   
   ...SYNOPSIS...
   IA UPR LOW EXPECTED TO CONTINUE NE TO LK SUPERIOR BY THIS
   EVE...BEFORE BECOMING ABSORBED WITHIN UPSTREAM TROUGH AMPLIFYING ESE
   FROM THE CANADIAN PRAIRIES.  A LOBE OF VORTICITY EXTENDING SW FROM
   THE IA LOW...WITH AN ASSOCIATED VORT MAX NOW IN SW OK PER WV
   IMAGERY...SHOULD CONTINUE ENE INTO OZARKS AND LWR OH VLY BY LATE IN
   THE DAY.
   
   AT THE SFC...A BROAD SWATH OF SWLY FLOW WILL PREVAIL OVER THE CNTRL
   AND ERN STATES DOWNSTREAM FROM AMPLIFYING LARGER SCALE TROUGH
   APPROACHING THE W CST.  AN AXIS OF LOW LVL CONFLUENCE WITHIN THE
   SWLY FLOW...ESSENTIALLY MARKING THE WRN FRINGE OF STRONG SFC HIGH
   OFF THE S ATLANTIC CST...WILL PROGRESS SLOWLY E ACROSS THE LWR MS
   AND LWR TN VLYS TODAY. 
   
   ...NRN IL/LWR MI INTO NRN IND/NRN OH THIS AFTN INTO TNGT...
   IT APPEARS THAT STRONGEST FORCING FOR ASCENT WITH IA UPR SYSTEM WILL
   TRACK NE ACROSS WI AND NRN MI LATER TODAY...BEYOND AXIS OF LOW LVL
   AIR MASS RECOVERY NOW OCCURRING NWD THROUGH THE MID MS AND LWR OH
   VLYS.  NEVERTHELESS...SATELLITE SUGGESTS THAT A SECONDARY WAVE OF
   ASCENT WILL OVERSPREAD MUCH OF IL...NRN IND...AND LWR MI LATER TODAY
   FOLLOWING MAX HEATING. 
   
   GIVEN BROAD SFC TROUGH ALREADY IN PLACE ACROSS THE N CNTRL
   STATES...EXPECT THAT THE MAIN SFC REFLECTION OF THE IA LOW WILL
   BE AN AXIS OF ENHANCED CONFLUENCE THAT SHOULD EVOLVE BY EARLY AFTN
   FROM CNTRL/NRN IL NEWD SRN/CNTRL LWR MI.  THIS CONFLUENCE AXIS
   SHOULD SERVE AS THE MAIN FOCUS FOR STORM DEVELOPMENT LATER THIS AFTN
   AND EVE AS DAYTIME HEATING...CONTINUED LOW LVL MOISTURE INFLOW...AND
   APPROACH OF SECONDARY UPR IMPULSE DESTABILIZE REGION.  
   
   SFC DEWPOINTS IN THE MID 50S F BENEATH 500 MB TEMPS AOA MINUS 16C
   SHOULD YIELD SBCAPE OF 500-1000 J/KG...AMPLE FOR SUSTAINED
   STORMS/SUPERCELLS GIVEN 50-60 KT WSWLY DEEP SHEAR.  A POTENTIAL WILL
   EXIST FOR BOTH TORNADOES AND BOWING SEGMENTS GIVEN 60+ KT 700 MB
   FLOW AND SIZABLE LOW LVL DIRECTIONAL SHEAR.  THE SVR THREAT SHOULD
   BE GREATEST FROM MID TO LATE AFTN THROUGH EARLY TNGT IN PARTS OF LWR
   MI AND ADJACENT NRN IL/IND...ALTHOUGH A MORE LIMITED THREAT MAY
   PERSIST THROUGH EARLY TUE EWD ACROSS THE LK ERIE REGION. 
   
   ...MID SOUTH/CNTRL GULF CST THIS AFTN...
   OVERNIGHT PROGRESSIVE MCS HAS SOMEWHAT STABILIZED THE CNTRL GULF CST
   REGION THIS MORNING.  THE ERN PART OF THE SYSTEM SHOULD CONTINUE
   FORWARD-PROPAGATING INTO LOW LVL ESELY FLOW OVER THE FL PANHANDLE
   AND SRN AL.  THE STORMS SHOULD WEAKEN AS THE SYSTEM PROPAGATES
   FARTHER E BEYOND LOW LVL MOIST AXIS OFF THE LA CST.
   ADDITIONAL STORMS MAY FORM WITH DAYTIME HEATING ALONG WRN SIDE OF
   MCS...I.E. OVER SRN LA.  THESE MAY POSE A LIMITED SVR RISK IN THE
   FORM OF LOCALLY DMG WIND OR A BRIEF TORNADO GIVEN RICH MOISTURE
   INFLOW...ALTHOUGH MODEST SHEAR/WEAK FORCING FOR ASCENT SHOULD LIMIT
   OVERALL THREAT.  
   
   FARTHER N...EXPECT MODERATE AFTN DESTABILIZATION /SBCAPE AOA 1500 J
   PER KG/ TO OCCUR OVER PARTS OF MS...WRN TN...AND SRN KY...IN ZONE OF
   LOW LVL MOISTURE RETURN ALONG AND E OF AFOREMENTIONED CONFLUENCE
   ZONE.  FORCING FOR ASCENT WILL BE WEAK...ALTHOUGH SOME ASCENT MAY
   OCCUR IN ASSOCIATION WITH CONTINUED EWD MOTION OF OK UPR IMPULSE. 
   THIS SETUP SHOULD SUPPORT ISOLD TO SCTD AFTN SHOWERS/STORMS.  GIVEN
   EXPECTED BUOYANCY AND 30-40 KT WSWLY DEEP SHEAR ON SRN FRINGE OF IA
   UPR LOW...A FEW STRONG TO SVR STORMS CAPABLE OF SVR HAIL AND/OR WIND
   COULD OCCUR.
   
   ..CORFIDI/SMITH.. 03/12/2012
   
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