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< Day 3 Outlook    
Day 4-8 Severe Weather Outlook Issued on May 21, 2013
Updated: Tue May 21 08:49:03 UTC 2013
D4-8 D4 D5 D6 D7 D8
 Population  Cities/Towns  CWAs  Interstates  Counties  FEMA Regions

Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
D4Fri, May 24, 2013 - Sat, May 25, 2013 D7Mon, May 27, 2013 - Tue, May 28, 2013
D5Sat, May 25, 2013 - Sun, May 26, 2013 D8Tue, May 28, 2013 - Wed, May 29, 2013
D6Sun, May 26, 2013 - Mon, May 27, 2013 (All days are valid from 12 UTC - 12 UTC the following day)
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 210848
   SPC AC 210848
   
   DAY 4-8 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0348 AM CDT TUE MAY 21 2013
   
   VALID 241200Z - 291200Z
   
   ...DISCUSSION...
   MEDIUM-RANGE MODELS IN DECENT AGREEMENT THROUGH ROUGHLY DAY 6 /SUN.
   12-26/...IN TERMS OF THE LARGE-SCALE PATTERN.
   
   DAY 4 /FRI. 12-24/...BOTH THE GFS AND ECMWF SHOW THE ERN U.S. TROUGH
   CONTINUING TO PROGRESS...WITH THE SURFACE COLD FRONT MOVING OFFSHORE
   EARLY IN THE PERIOD -- SUGGESTING ONLY LOW-END SEVERE THREAT AT BEST
   PRIOR TO THE FRONT VACATING THE COAST.
   
   MEANWHILE...A STRONG RIDGE OVER THE CENTRAL U.S. IS PROGGED TO
   PERSIST...HINDERING EWD PROGRESSION OF THE WRN U.S. TROUGH.  MODELS
   AGREE OVERALL -- BUT DIFFER WITH DETAILS -- THAT THE RIDGE WILL
   DEAMPLIFY/FLATTEN WITH TIME...AS SHORT-WAVE TROUGHS EJECT EWD FROM
   THE MAIN WRN SYSTEM INTO THE MEAN RIDGING.  WHILE THE DECREASE IN
   RIDGING -- AND THUS LARGE-SCALE SUBSIDENCE -- WITH TIME COMBINED
   WITH THE PASSAGE OF REPEATED VORTICITY MAXIMA WOULD RESULT IN SOME
   SEVERE POTENTIAL LOCALLY...TIMING/LOCATION WOULD BE QUITE DIFFICULT
   TO NARROW DOWN ATTM.  EVEN SO...WITH NO WIDESPREAD/SIGNIFICANT
   THREATS EVIDENT ATTM -- BUT MORE LIKELY SMALLER-SCALE/LOCAL
   POTENTIAL...NO OUTLOOK AREAS WILL BE ISSUED THIS FORECAST.
   
   ..GOSS.. 05/21/2013

   CLICK TO GET WUUS48 PTSD48 PRODUCT


To retrieve previous Day 4-8 convective outlooks, enter the date YYYYMMDD (e.g., 20050310 for March 10, 2005.)
Data available since March 8, 2005.
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Page last modified: May 21, 2013
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