National Weather Service United States Department of Commerce

Flash Flood Threats in the Southeast and Rockies; Excessive Heat in the Southwest

Flash and small stream flooding threats linger across the southern Rockies Wednesday. Strong thunderstorms with heavy downpours may cause local flash flooding along portions of the Southeast states into Thursday. Excessive heat will continue to impact the southern California mountains and deserts into Arizona and Nevada into Thursday. Read More >

Day 4-8 Severe Weather Outlook issued at 0850 UTC on 24 April 2011

ZCZC SPCSWOD48 ALL
   ACUS48 KWNS 240850
   SPC AC 240850
   
   DAY 4-8 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0350 AM CDT SUN APR 24 2011
   
   VALID 271200Z - 021200Z
   
   ...DISCUSSION...
   WIDESPREAD CONVECTIVE/SEVERE WEATHER EVENT -- ONGOING FROM THE DAY 3
   /TUE. 4-26/ PERIOD -- IS LIKELY TO CONTINUE SPREADING EWD ACROSS THE
   OH/TN VALLEYS AND GULF COAST STATES DAY 4 /WED. 4-27/...AS
   MEDIUM-RANGE MODELS BOTH FORECAST EWD PROGRESSION OF THE LARGE
   CENTRAL U.S. TROUGH.  AS THE COLD FRONT SHIFTS EWD TOWARD THE
   APPALACHIANS THROUGH THE AFTERNOON AND EVENING...PRE-FRONTAL WARM
   SECTOR FEATURING MODERATE INSTABILITY AND STRONG DEEP-LAYER SHEAR
   WILL SUPPORT CONTINUATION/REDEVELOPMENT OF SEVERE STORMS INTO THE
   AFTERNOON AND EVENING.  POTENTIAL FOR SUBSTANTIAL SEVERE WEATHER --
   INCLUDING HAIL/WIND AND ISOLATED TORNADOES -- SUPPORTS CONTINUATION
   OF A LARGE SEVERE WEATHER THREAT AREA FOR DAY 4.  
   
   MODEL TIMING WITH RESPECT TO THE SURFACE FRONT AND ASSOCIATED UPPER
   TROUGH BEGINS TO DIFFER MORE SUBSTANTIALLY DAY 5 /THU. 4-28/...THUS
   CASTING SOME UNCERTAINTY WITH RESPECT TO LOCATION AND DEGREE OF
   THREAT E OF THE APPALACHIANS DAY 5.  THEREFORE...WHILE POTENTIALLY
   SEVERE CONVECTION WILL LIKELY SPREAD ACROSS THE ATLANTIC COAST
   STATES SOMEWHERE BETWEEN LATE IN THE DAY 4 PERIOD AND THE AFTERNOON
   AND EVENING OF DAY 5...WILL NOT HIGHLIGHT A SPECIFIC THREAT AREA
   THIS FORECAST.
   
   WITH THE FRONT EXPECTED TO HAVE SWEPT OFFSHORE BY THE START OF DAY 6
   /FRI. 4-29/...FOCUS SHIFTS WWD AS THE NEXT SYSTEM SHIFTS ACROSS/OUT
   OF THE ROCKIES.  MODELS ARE IN MORE SUBSTANTIAL DISAGREEMENT WITH
   THE EVOLUTION AND PROGRESSION OF THIS FEATURE...AND THUS WILL NOT
   HIGHLIGHT ANY LONGER-RANGE THREAT AREAS THIS FORECAST.
   
   ..GOSS.. 04/24/2011

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