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< Day 3 Outlook    
Day 4-8 Severe Weather Outlook Issued on May 18, 2013
Updated: Sat May 18 09:00:04 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
D4Tue, May 21, 2013 - Wed, May 22, 2013 D7Fri, May 24, 2013 - Sat, May 25, 2013
D5Wed, May 22, 2013 - Thu, May 23, 2013 D8Sat, May 25, 2013 - Sun, May 26, 2013
D6Thu, May 23, 2013 - Fri, May 24, 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 180859
   SPC AC 180859
   
   DAY 4-8 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0359 AM CDT SAT MAY 18 2013
   
   VALID 211200Z - 261200Z
   
   ...DISCUSSION...
   THE MEDIUM RANGE MODELS BEGIN THE DAY 4 TO 8 PERIOD WITH AN
   UPPER-LEVEL TROUGH OVER THE CNTRL HIGH PLAINS AND SRN ROCKIES WITH
   SOUTHWEST FLOW LOCATED FROM THE SCNTRL STATES NEWD INTO THE GREAT
   LAKES REGION. STRONG TO POSSIBLY SEVERE THUNDERSTORM DEVELOPMENT
   WILL BE POSSIBLE ON TUESDAY/DAY 4 ALONG A CORRIDOR OF MODERATE
   INSTABILITY FROM THE SRN PLAINS EXTENDING NEWD INTO THE MID MS
   VALLEY. ON WEDNESDAY/DAY 5...THE MODELS MOVE THE UPPER-LEVEL TROUGH
   EWD INTO THE OZARKS WITH A COLD FRONT LOCATED FROM THE OH VALLEY
   SWWD INTO THE ARKLATEX. STRONG THUNDERSTORM DEVELOPMENT WILL BE
   POSSIBLE WEDNESDAY AND WEDNESDAY NIGHT ALONG AND AHEAD OF THE FRONT.
   ON THURSDAY/DAY 6...THE MODELS MAINTAIN REASONABLE AGREEMENT WITH AN
   UPPER-LEVEL RIDGE BUILDING ACROSS THE GREAT PLAINS AND AN
   UPPER-LEVEL TROUGH LOCATED IN THE ERN STATES. THUNDERSTORMS WILL BE
   POSSIBLE ALONG THE ERN SEABOARD THURSDAY AFTERNOON AND EVENING WITH
   MORE ISOLATED DEVELOPMENT POSSIBLE IN THE SRN PLAINS. MODEL
   SOLUTIONS DIVERGE ON FRIDAY/DAY 7 SUGGESTING UNCERTAINTY IS
   SUBSTANTIAL AT THAT RANGE.
   
   AT THIS POINT...TUESDAY/DAY 4 AND WEDNESDAY/DAY 5 APPEAR TO HAVE THE
   GREATEST CHANCE FOR AN ENHANCED SEVERE THREAT AREA. ON THOSE
   DAYS...A POTENTIAL FOR SEVERE STORMS WILL EXIST ACROSS A BROAD
   CORRIDOR. MESOSCALE INTERACTIONS WILL PROBABLY BE IMPORTANT AS TO
   WHERE THE SEVERE THREAT ENDS UP BECOMING ENHANCED. FOR THAT
   REASON...WILL GO PREDICTABILITY TOO LOW FOR THIS OUTLOOK.
   
   ..BROYLES.. 05/18/2013

   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 18, 2013
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