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Day 4-8 Severe Weather Outlook Issued on Apr 20, 2011
Updated: Wed Apr 20 15:02:57 UTC 2011
Day 4-8 Severe Weather Outlook Graphics Issued on Apr 20, 2011
D4Sat, Apr 23, 2011 - Sun, Apr 24, 2011 D7Tue, Apr 26, 2011 - Wed, Apr 27, 2011
D5Sun, Apr 24, 2011 - Mon, Apr 25, 2011 D8Wed, Apr 27, 2011 - Thu, Apr 28, 2011
D6Mon, Apr 25, 2011 - Tue, Apr 26, 2011 (All days are valid from 12 UTC - 12 UTC)
Note: A severe weather area depicted in the Day 4-8 period indicates a 30% or higher probability for severe thunderstorms within 25 miles of any point.
PREDICTABILITY TOO LOW is used to indicate severe storms may be possible based on some model scenarios. However, the location or occurrence of severe storms are in doubt due to: 1) large differences in the deterministic model solutions, 2) large spread in the ensemble guidance, and/or 3) minimal run-to-run continuity.
POTENTIAL TOO LOW means the threat for a regional area of organized severe storms appears highly unlikely during the entire period (e.g. less than a 30% probability for a regional severe storm area across the CONUS through the entire Day 4-8 period).

 Forecast Discussion

   ZCZC SPCSWOD48 ALL
   ACUS48 KWNS 200845
   SPC AC 200845
   
   DAY 4-8 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0345 AM CDT WED APR 20 2011
   
   VALID 231200Z - 281200Z
   
   ...DISCUSSION...
   AMPLIFICATION OF THE LARGE SCALE PATTERN IS PROBABLE BY THIS
   WEEKEND/EARLY NEXT WEEK VIA A WESTERN STATES TROUGH AS PER 00Z
   ECMWF/GEFS/UKMET GUIDANCE. WHILE PERIODIC BOUTS OF SEVERE WEATHER
   WILL UNDOUBTEDLY OCCUR DURING THE PERIOD...CONFIDENCE IN THE
   DELINEATION OF SPECIFIC 30 PERCENT CALIBER SEVERE RISK AREAS IS
   LIMITED OWING TO UNCERTAINTY REGARDING SHORTWAVE-TYPE FEATURES AS
   RELATED TO THE MOIST SECTOR.
   
   ON DAYS 4-5 SATURDAY/SUNDAY...THE SOUTHERN PLAINS WILL BE A FOCUS
   FOR AT LEAST SOME SURFACE BASED SEVERE THREAT NEAR/EAST OF A DRYLINE
   ACROSS WEST TX AND PERHAPS INTO OK. OTHER SEVERE TSTMS MAY BE
   POSSIBLE ALONG AND NORTH /IN AN ELEVATED SENSE/ OF THE FRONTAL
   BOUNDARY EXTENDING NORTHEASTWARD FROM THE SOUTHERN PLAINS INTO THE
   MIDDLE MS RIVER VALLEY. IN ADDITION TO A DEGREE OF MEDIUM RANGE
   NUMERICAL GUIDANCE VARIABILITY...A PARTICULARLY
   WIDESPREAD/APPRECIABLE SEVERE RISK IS NOT CURRENTLY ANTICIPATED.
   
   WITH LIKELY AMPLIFICATION OF THE LARGE SCALE PATTERN VIA THE
   EVOLUTION OF A PROMINENT WESTERN/CENTRAL CONUS UPPER TROUGH BY DAYS
   5-6 SUNDAY/MONDAY...PRELIMINARY THINKING IS THAT A MORE
   WIDESPREAD/MULTI-ROUND SEVERE THREAT MAY EVOLVE THROUGH DAYS 6-8
   MONDAY/TUESDAY/WEDNESDAY FROM THE SOUTHERN PLAINS EAST-NORTHEASTWARD
   INTO THE MIDWEST/MS RIVER VALLEY. BUT...SPECIFIC PREDICTABILITY IS
   STILL QUITE LIMITED IN THIS TIME FRAME.
   
   ..GUYER.. 04/20/2011

   CLICK TO GET WUUS48 PTSD48 PRODUCT

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