Feb 28, 2007 2000 UTC Day 1 Convective Outlook
Updated: Wed Feb 28 20:04:09 UTC 2007
Probabilistic to Categorical Outlook Conversion Table (Effective Feb 14, 2006).
Public Severe Weather Outlook

The SPC is forecasting ...severe thunderstorms expected over parts of the lower mississippi valley tonight....   Please read the latest public statement about this event.

Categorical Graphic
20070228 2000 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20070228 2000 UTC Day 1 Tornado Probabilities Graphic
Probabilistic Damaging Wind Graphic
20070228 2000 UTC Day 1 Damaging Wind Probabilities Graphic
Probabilistic Large Hail Graphic
20070228 2000 UTC Day 1 Large Hail Probabilities Graphic
   SPC AC 282000
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0200 PM CST WED FEB 28 2007
   
   VALID 282000Z - 011200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS PORTIONS SRN/CENTRAL MO...NRN
   AR...NERN/EXTREME E-CENTRAL OK...EXTREME SERN KS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ELSEWHERE FROM CENTRAL KS TO
   WRN TN AND SERN OK TO SWRN IL...
   
   ...SYNOPSIS...
   STRONG SHORTWAVE TROUGH  -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY
   OVER LOWER CO RIVER VALLEY -- IS FCST TO MOVE EWD ACROSS SRN ROCKIES
   THIS EVENING...THEN TURN NEWD OVER KS AND AMPLIFY.  MIDLEVEL LOW
   SHOULD EVOLVE FROM THIS SYSTEM NEAR END OF PERIOD ACROSS NERN KS. 
   500 MB SPEED MAX TO ITS S SHOULD STRENGTHEN TO 100-110 KT RANGE OVER
   SRN OK AND NW TX...BENEATH 150-170 KT 250 MB JET.
   
   AT SFC...CYCLONE NOW DEEPENING OVER OK PANHANDLE/NWRN OK REGION IS
   EXPECTED TO EJECT NEWD ACROSS KS INTO NRN MO
   OVERNIGHT...STRENGTHENING SUBSTANTIALLY.  DRYLINE -- NOW ANALYZED
   FROM SERN KS SWWD ACROSS SWRN OK -- MAY MIX EWD SOMEWHAT OVER SRN OK
   WHILE MOISTURE BUILDS ACROSS NERN OK AND SERN KS...RESULTING IN NET
   CYCLONIC PIVOT TO ITS ORIENTATION THROUGH EVENING.  SFC COLD FRONT
   -- NOW EVIDENT OVER WRN OK PANHANDLE AND SERN CO -- WILL SWEEP SEWD
   ACROSS MOST OF OK AND W-CENTRAL/NW TX BY END OF PERIOD.  WARM FRONT
   -- NOW OVER W-CENTRAL THROUGH SERN MO -- WILL LIFT NEWD ACROSS NERN
   MO AND SRN IL OVERNIGHT.
   
   ...KS/OK DRYLINE...BEFORE DARK...
   CONDITIONAL POTENTIAL REMAINS FOR SFC-BASED CONVECTIVE INITIATION
   DURING NEXT SEVERAL HOURS...ALONG OR E OF DRYLINE FROM S-CENTRAL
   THROUGH N-CENTRAL/NERN OK AND S-CENTRAL/SERN KS.  MAIN LIMITING
   FACTOR MAY BE LACK OF DEEPER AND MORE ROBUST MOIST LAYER...DESPITE
   SFC DEW POINTS STEADILY INCREASING ATTM INTO UPPER 50S AND LOW 60S
   F...SE OF I-44.  GPS PW DATA INDICATES INCREASINGLY ROBUST MOISTURE
   ACROSS S-CENTRAL/SERN OK...WHICH MAY LIFT NWD AS LOW LEVEL
   PRESSURES/HEIGHTS FALL ACROSS SRN PLAINS...CONTRIBUTING TO SOME
   BACKING OF FLOW.  RUC FCST CONVECTIVE DEVELOPMENT PRIOR TO 00Z
   APPEARS TO BE ALONG SSW-NNE EDGE OF DRYLINE NEAR 900-925 MB LAYER.
   
   ANY TSTMS THAT DEVELOP IN THIS ENVIRONMENT BEFORE DARK MAY BECOME
   SUPERCELLS...PRODUCING LARGE HAIL AND DAMAGING GUSTS.  TORNADO
   POTENTIAL SHOULD INCREASE AFTER DARK E OF DRYLINE AS BOUNDARY LAYER
   THETAE STRENGTHENS...LCL LOWERS...AND 0-1 KM SHEAR INCREASES BENEATH
   STRENGTHENING LLJ.
   
   ...MO/AR/ERN OK TO MS RIVER VALLEY...AFTER DARK...
   THREAT WILL INCREASE FURTHER AFTER ABOUT 1/06Z..ALONG AND S OF WARM
   FRONT.  EXPECT SUPERCELLS AND BOWING LINE SEGMENTS...WITH DAMAGING
   WIND AND TORNADOES BEING MAIN CONCERNS.  GIVEN FAST EXPECTED STORM
   MOTIONS...A FEW LONG TRACK TORNADIC SUPERCELLS ARE POSSIBLE LATE
   TONIGHT...PARTICULARLY INVOF OZARKS...AS INCREASINGLY FAVORABLE LOW
   LEVEL MOISTURE PLUME BECOMES MORE VERTICALLY JUXTAPOSED WITH INTENSE
   DEEP-LAYER SHEAR PROFILES.
   
   MOIST ADVECTION WILL BOOST SFC DEW POINTS INTO UPPER 50S AND LOW 60S
   BY END OF PERIOD...AMIDST STRONG LOW LEVEL WAA REGIME.  ASSOCIATED
   INCREASE IN BOUNDARY LAYER THETAE WILL OFFSET/HINDER SFC DIABATIC
   COOLING ENOUGH TO KEEP EFFECTIVE INFLOW PARCELS ROOTED AT OR VERY
   NEAR SFC.  7-8 DEG C/KM 700-500 MB LAPSE RATES ARE
   EXPECTED...ASSOCIATED WITH NEWD ADVECTION OF UPPER PORTION OF
   ELEVATED MIXED LAYER/EML.  THIS WILL CONTRIBUTE TO SBCAPES IN
   500-800 J/KG RANGE...WHICH IS MORE THAN SUFFICIENT TO SUPPORT SVR
   POTENTIAL GIVEN VERY STRONG FLOW ALOFT THAT WILL OVERSPREAD AREA. 
   LOW LEVEL HODOGRAPHS WILL ENLARGE BENEATH 50-60 KT LLJ AND OVER SERN
   QUADRANT OF SFC CYCLONE...YIELDING 0-1 KM SRH 250-400 J/KG AND 35-40
   KT OF 0-1 KM VECTOR SHEAR MAGNITUDE...WHILE 0-6 KM SHEARS AOA 50 KT
   WILL BE COMMON.
   
   CAPPING AT BASE OF EML -- NOW QUITE STRONG PER 18Z SGF RAOB --
   SHOULD WEAKEN WITH TIME TONIGHT AS DEEP-LAYER ASCENT AND LOW LEVEL
   THETAE EACH INCREASE.  AFTER 1/06Z...CINH IS EXPECTED TO WEAKEN WITH
   NWD EXTENT FROM ARKLATEX REGION ACROSS ERN OK AND AR...RESULTING IN
   POTENTIAL FOR SCATTERED-NUMEROUS TSTMS IN BANDS AND CLUSTERS BY 12Z.
   
   
   ...S FL...
   BRIEFLY TORNADIC/HAIL PRODUCING SUPERCELL -- THAT DEVELOPED INVOF
   COLD FRONT/SEA BREEZE INTERSECTION AND THEN MOVED BEHIND SEA BREEZE
   -- HAS MOVED OFFSHORE.  OTHER ACTIVITY IS EVIDENT INVOF ATLANTIC SEA
   BREEZE BOUNDARY NOW MOVING SWWD ACROSS HENDRY ERN COLLIER/SWRN
   BROWARD/MIAMI-DADE COUNTIES...AND ALONG SMALLER SW COAST SEA BREEZE
   SEGMENT SE APF.  OPTIMALLY BACKED SFC WINDS WILL REMAIN E OF
   ATLANTIC BOUNDARY...HOWEVER BUOYANCY IS EXPECTED TO DIMINISH THROUGH
   REMAINDER AFTERNOON AS COMBINED SEA BREEZE/OUTFLOW AIR AND SPREADS
   OVER MORE OF REGION.  MEANWHILE...STRONGER CELLS MAY PRODUCE
   HAIL/GUSTS NEAR SVR LEVELS.
   
   ..EDWARDS.. 02/28/2007
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z