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Day 4-8 Severe Weather Outlook Issued on Apr 8, 2012
Updated: Sun Apr 8 09:00:03 UTC 2012
Day 4-8 Severe Weather Outlook Graphics Issued on Apr 8, 2012
D4Wed, Apr 11, 2012 - Thu, Apr 12, 2012 D7Sat, Apr 14, 2012 - Sun, Apr 15, 2012
D5Thu, Apr 12, 2012 - Fri, Apr 13, 2012 D8Sun, Apr 15, 2012 - Mon, Apr 16, 2012
D6Fri, Apr 13, 2012 - Sat, Apr 14, 2012 (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 080859
   SPC AC 080859
   
   DAY 4-8 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0359 AM CDT SUN APR 08 2012
   
   VALID 111200Z - 161200Z
   
   ...DISCUSSION...
   ALTHOUGH MEDIUM RANGE MODELS /00Z ECMWF AND GFS/ DIFFER IN THE TRACK
   OF A TROUGH INTO THE CENTRAL U.S. ON D5/THU AND TO SOME DEGREE ON
   D7/SAT...THESE MODELS DO AGREE IN A PATTERN CHANGE ACROSS THE CONUS
   FROM MID WEEK TO NEXT WEEKEND.  A BLOCKING PATTERN WITH A NWLY FLOW
   REGIME OVER THE CENTRAL TO SERN U.S. WILL PERSIST INTO D4/WED WITH A
   THREAT FOR SEVERE STORMS ACROSS THE SRN AND CENTRAL HIGH PLAINS. 
   THE PATTERN CHANGE BEGINS ON D5 AS SWLY FLOW DEVELOPS INTO THE
   PLAINS DOWNSTREAM OF A LONGWAVE TROUGH EVOLVING OVER THE WRN STATES
   THROUGH THE REST OF THE EXTENDED PERIOD.
   
   FOR D5/THU...THE GFS AND ECMWF CONTINUE TO DIFFER WITH THE TRACK OF
   THE SHORTWAVE TROUGH FROM LATE D4/WED THROUGH D5.  ALTHOUGH THE GFS
   IS MAINTAINING A NRN TRACK BIAS WITH WEAKER FORCING ACROSS
   KS/OK...THE WARM SECTORS IN EACH MODEL ARE SIMILAR.  NORMALLY THESE
   TYPES OF MODEL VARIANCES IN THE MID-UPPER LEVELS WOULD RESULT IN NOT
   INCLUDING A REGIONAL SEVERE WEATHER THREAT AREA.  HOWEVER...GFS
   FORECAST SOUNDINGS SUGGEST THE POTENTIAL FOR SUPERCELLS ALONG THE
   DRY LINE...BUT WITH LOWER COVERAGE.  THIS FACTOR COMBINED WITH THE
   FORECAST FOR STRONGER WIND FIELDS PER THE ECMWF SUGGESTS THE
   REGIONAL SEVERE WEATHER THREAT AREA WILL BE MAINTAINED INTO D5 WITH
   THE POTENTIAL FOR LARGE HAIL AND TORNADOES.  
   
   THE MODEL DIFFERENCES WITH THE TRACK OF THE D5/THU TROUGH AFFECT THE
   SEVERE WEATHER FORECAST FOR D6/FRI...WITH THE GFS FAVORING A MORE
   NRN TRACK ACROSS KS/NEB INTO IA...WHILE THE ECMWF INDICATED A
   GREATER THREAT FARTHER TO THE SSE.  
   
   FOR D7/SAT...THE GFS/ECMWF ARE IN BETTER AGREEMENT AGAIN WITH
   RESPECT TO THE DISTRIBUTION OF LOW LEVEL MOISTURE AND WARM SECTOR
   SETUP ACROSS TX INTO KS.  GREATEST JUXTAPOSITION OF INSTABILITY AND
   STRONG DEEP LAYER SHEAR SUPPORTS ANOTHER REGIONAL SEVERE WEATHER
   THREAT AREA SIMILAR TO D5 ACROSS OK/KS.
   
   ..PETERS.. 04/08/2012

   CLICK TO GET WUUS48 PTSD48 PRODUCT

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