Mar 28, 2007 1630 UTC Day 1 Convective Outlook
Updated: Wed Mar 28 16:56:11 UTC 2007
Probabilistic to Categorical Outlook Conversion Table (Effective Feb 14, 2006).
Public Severe Weather Outlook

The SPC is forecasting ...widespread severe thunderstorms expected over the western half of the southern and central plains this afternoon and tonight....   Please read the latest public statement about this event.

Categorical Graphic
20070328 1630 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20070328 1630 UTC Day 1 Tornado Probabilities Graphic
Probabilistic Damaging Wind Graphic
20070328 1630 UTC Day 1 Damaging Wind Probabilities Graphic
Probabilistic Large Hail Graphic
20070328 1630 UTC Day 1 Large Hail Probabilities Graphic
   SPC AC 281633
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   ISSUED BY AFWA OFFUTT AIR FORCE BASE BELLEVUE NE
   1133 AM CDT WED MAR 28 2007
   
   VALID 281630Z - 291200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS FROM SW NEB TO NW TX...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM SRN SD TO SW TX...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM SRN VA TO NC/NRN SC...
   
   ...WIDESPREAD SEVERE THUNDERSTORMS INCLUDING DAMAGING WINDS...VERY
   LARGE HAIL AND POSSIBLY STRONG TORNADOES WILL DEVELOP OVER THE
   WESTERN HALF OF THE CENTRAL AND SOUTHERN PLAINS LATER TODAY AND
   TONIGHT...
     
   ...CENTRAL/SRN PLAINS...
   STRONG UPPER LOW WILL SHIFT INTO THE CENTRAL ROCKIES AND THEN BECOME
   STATIONARY OVERNIGHT.  AS THIS OCCURS...SURFACE DRY LINE WILL BECOME
   WELL ESTABLISHED OVER THE HIGH PLAINS AND LIKELY EXTEND FROM A LOW
   OVER FAR NERN CO SWD JUST EAST OF THE KS/CO BORDER INTO THE CENTRAL
   TX PANHANDLE AND FAR SWRN TX BY EARLY THIS EVENING.  WIDESPREAD
   THUNDERSTORM DEVELOPMENT JUST EAST OF THE DRY LINE IS EXPECTED AFTER
   20Z AS THE CAP WEAKENS...WITH SUPERCELLS AND SEVERE WEATHER LIKELY. 
   MLCAPE WILL RANGE FROM 1000-2000 J/KG ACROSS THE AREA...WHILE LOW
   LEVEL AND DEEP LAYER SHEAR WILL BE STRONG ALONG THE DRY LINE DESPITE
   STRONGEST MID LEVEL JET EXTENDING NNEWD BEHIND THE DRY LINE OVER ERN
   CO.  NORTHEAST OF THE LOW INTO NEBRASKA AND NORTHERN KANSAS...LOW
   CLOUDS ARE LIMITING SURFACE HEATING SO THAT STRONG CAPPING MAY
   PREVENT THUNDERSTORMS FROM FORMING THERE UNTIL LATER THIS EVENING.
     
   HOW LONG ACTIVITY REMAINS IN THE FORM OF DISCRETE SUPERCELLS REMAINS
   HARD TO SAY...AS ACTIVITY WILL LIKELY EVOLVE INTO LINEAR STRUCTURES
   AS IT MOVES ENEWD THROUGH THE EVENING. HOWEVER...VERY STEEP LAPSE
   RATES AND STRONG SHEAR WILL ENHANCE THE POTENTIAL FOR
   SIGNIFICANT/DAMAGING HAIL AND STRONG TORNADOES INTO THE EARLY-MID
   EVENING WITH ANY DISCRETE STORMS.  WIND DAMAGE THREAT SHOULD ALSO
   INCREASE AS LINEAR ORGANIZATION BECOMES MORE PREDOMINANT THIS
   EVENING...BUT THIS WILL BE TEMPERED BY SLOW FORWARD MOTION OF THE
   CONVECTION DUE TO LINE PARALLEL FLOW.  LACK OF EWD PROGRESSION WITH
   OVERALL SYSTEM AND NARROW INSTABILITY AXIS SUGGESTS STORMS SHOULD
   WEAKEN AS THEY MOVE ACROSS CENTRAL SD/NE/KS/OK LATER THIS EVENING.
     
   NAM AND GFS ARE ALSO INDICATING SECONDARY LOBE OF ENERGY ROTATING
   AROUND LARGE UPPER LOW AND INTO THE NERN NM/SERN CO LATE TONIGHT. 
   THIS SHOULD SUPPORT DEVELOPMENT OF ANOTHER MCS...POSSIBLY
   SEVERE...OVER WRN TX INTO WRN OK/SWRN KS OVERNIGHT.
   
   ...WY/SD/NE...
   RUC FORECAST SOUNDINGS INDICATE AROUND 500-1000 J/KG OF SBCAPE ALONG
   WITH 150-250 J/KG EFFECTIVE HELICITY AND 60-80 KNOTS OF DEEP LAYER
   SHEAR EARLY THIS AFTERNOON.  CURRENT INDICATIONS ARE THAT SURFACE
   TEMPERATURES ARE SEVERAL DEGREES WARMER THAN IN THE RUC WHICH WILL
   ADD TO THE INSTABILITY.  STRONG VERTICAL MOTION WITH THE APPROACH OF
   THE TROUGH SHOULD CAUSE SURFACE BASED THUNDERSTORM INITIATION AROUND
   18-19Z POSSIBLY LEADING TO LOW TOPPED SUPERCELLS WITH LARGE HAIL AND
   A FEW TORNADOES POSSIBLE.
     
   ...CENTRAL APPALACHIANS INTO NC...
   COLD FRONT NOW EXTENDING FROM SERN VA INTO CENTRAL KY WILL SAG SSWWD
   AS A BACK-DOOR FRONT INTO NC AND EXTEND ROUGHLY E-W FROM ERN NC INTO
   SWRN VA BY LATE THIS AFTERNOON.  THIS WILL OCCUR UNDER EJECTING
   SHORTWAVE TROUGH AND ASSOCIATED 35-45 KT MID LEVEL JET NOW OVER
   KY/TN WHICH WILL MOVE EWD ACROSS THIS REGION TODAY.  NAM-KF
   SOUNDINGS NEAR AND JUST NORTH OF THE FRONT INDICATE EFFECTIVE BULK
   SHEAR WILL SUPPORT SUPERCELLS AND ORGANIZED CLUSTERS AS AIR MASS
   BECOMES MARGINALLY TO MODERATELY UNSTABLE.  LARGE HAIL AND DAMAGING
   DOWNBURST WINDS ARE THE MAIN SEVERE THREATS...BUT A TORNADO OR TWO
   IS POSSIBLE.
   
   ..AFWA.. 03/28/2007
   
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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z