Mar 21, 2007 1300 UTC Day 1 Convective Outlook
Updated: Wed Mar 21 12:30:15 UTC 2007
Probabilistic to Categorical Outlook Conversion Table (Effective Feb 14, 2006).
Categorical Graphic
20070321 1300 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20070321 1300 UTC Day 1 Tornado Probabilities Graphic
Probabilistic Damaging Wind Graphic
20070321 1300 UTC Day 1 Damaging Wind Probabilities Graphic
Probabilistic Large Hail Graphic
20070321 1300 UTC Day 1 Large Hail Probabilities Graphic
   SPC AC 211227
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0727 AM CDT WED MAR 21 2007
   
   VALID 211300Z - 221200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF UPPER
   MIDWEST...CENTRAL AND SOUTHERN PLAINS...
   
   ...SYNOPSIS...
   COMPLEX SPLIT FLOW AS VIGOROUS S/WV MOVES RAPIDLY EWD FROM NRN
   PLAINS TO UPPER GREAT LAKES IN NRN BRANCH WHILE TROUGH WRN U.S. DIGS
   SWD TO DEVELOP A CUT-OFF LOW W OF NRN BAJA BY 12Z THU.  COLD FRONT
   CURRENTLY ACROSS DAKOTAS WILL CONTINUE E/SE TO BE ACROSS ERN MN/NWRN
   IA TO NWRN KS BY LATE THIS AFTERNOON.  WARM FRONT FROM SCENTRAL NEB
   SEWD TO SRN MO LIFTING NWD INTO SRN IA PRIOR TO COLD FRONT PASSAGE
   EARLY TONIGHT.
   
   40-50KT LOW LEVEL JET CONTINUES TO INCREASE GULF MOISTURE NWD THRU
   THE SRN/CENTRAL PLAINS AHEAD OF THE COLD FRONT.  ATOP THE MOIST
   RETURN AN ELEVATED MIX LAYER CHARACTERIZED BY MID LEVEL LAPSE RATES
   IN EXCESS OF 8C/KM IS SPREADING EWD ACROSS THE PLAINS .  THIS WILL
   MAINTAIN A LID ON SURFACE BASED INITIATION OF CONVECTION MUCH OF
   AFTERNOON.
   
   ....ERN NEB/NERN KS...IA AND NWRN MO...
   WITH DEWPOINTS RISING INTO THE LOW 60S ACROSS MUCH OF ERN KS AND
   POSSIBLY INTO SERN NEB/SWRN IA...AIR MASS BECOMES MODERATELY
   UNSTABLE THIS AFTERNOON WITH MLCAPES AOA 2000 J/KG. LATER THIS
   AFTERNOON WITH TEMPERATURES RISING INTO LOWER 70S POSSIBLY AS FAR N
   AS SERN NEB/SWRN IA...CIN WILL DECREASE SUFFICIENTLY TO SUPPORT
   POTENTIAL SURFACE INITIATION AHEAD OF THE COLD FRONT. WITH MODEL
   SOUNDINGS INDICATING 20KT OF SFC-1KM SHEAR AND UP TO 40KT DEEP LAYER
   SHEAR...SUPERCELLS ARE LIKELY WITH ANY STORM DEVELOPMENT.  WHILE
   PRIMARY THREAT EARLY IN THE CONVECTIVE EVENT WILL BE LARGE
   HAIL...HAVE INCREASED THE TORNADO THREAT FOR A COUPLE HOURS EITHER
   SIDE OF SUNSET WITH ANY DISCRETE STORM THAT DEVELOPS.
   
   BY THE EVENING THE FRONTAL CONVERGENCE SHOULD FORCE STORM
   DEVELOPMENT FROM SERN MN SWWD EVENTUALLY OVERNIGHT INTO NERN KS/NWRN
   MO.  MODE SHOULD BE PRIMARILY MULTI-CELL AND LINE SEGMENTS. ALONG
   WITH THE LARGE HAIL THREAT GIVEN THE MDT INSTABILITY AND STEEP LAPSE
   RATES...WIND DAMAGE WOULD BE LIKELY ASSOCIATED WITH ANY LINE
   SEGMENTS/BOWS.
   
   ...KS SWD INTO WRN TX...
   AS UPPER LOW DEVELOPS WELL TO THE SW  OFF NRN BAJA AND TROUGH
   CROSSES NRN PLAINS...THE CENTRAL/SRN HIGH PLAINS WILL BE UNDER
   30-40KT SWLY 500MB FLOW. DRY LINE EXPECTED TO MIX EWD INTO CENTRAL
   KS SSWWD THRU ERN TX PANHANDLE TO THE TRANS PECOS AREA.  WHILE
   MUCAPES E OF DRY LINE WILL INCREASE TO 2500 J/KG...CAP WILL ONLY
   ERODE WITH HEATING SUFFICIENTLY ALONG WESTERN EDGE OF MOISTURE FOR A
   CONDITIONAL THREAT OF SURFACE DEVELOPMENT BY LATE THIS AFTERNOON. 
   WITH AVAILABLE INSTABILITY AND 30KTS OF DEEP LAYER SHEAR...ANY STORM
   WILL BE POTENTIALLY SEVERE/SUPERCELLULAR.  LARGE HAIL WOULD BE
   PRIMARY THREAT. AN AREA OF A LITTLE GREATER POTENTIAL FOR SEVERE
   STORM DEVELOPMENT WILL BE THE INTERSECTION OF DRY LINE/COLD FRONT
   NCENTRAL KS/NEB BORDER VICINITY BY THIS EVENING.
   
   ..HALES/GUYER.. 03/21/2007
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z