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Day 4-8 Severe Weather Outlook Issued on May 1, 2015
Updated: Fri May 1 08:55:02 UTC 2015
Day 4-8 Severe Weather Outlook Graphics Issued on May 1, 2015
Day 4 Severe Weather Outlook Graphics Issued on May 1, 2015
Day 4 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Day 5 Severe Weather Outlook Graphics Issued on May 1, 2015
Day 5 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Day 6 Severe Weather Outlook Graphics Issued on May 1, 2015
Day 6 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Day 7 Severe Weather Outlook Graphics Issued on May 1, 2015
Day 7 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Day 8 Severe Weather Outlook Graphics Issued on May 1, 2015
Day 8 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
D4Mon, May 04, 2015 - Tue, May 05, 2015 D7Thu, May 07, 2015 - Fri, May 08, 2015
D5Tue, May 05, 2015 - Wed, May 06, 2015 D8Fri, May 08, 2015 - Sat, May 09, 2015
D6Wed, May 06, 2015 - Thu, May 07, 2015 (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 15%, 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 unlikely (i.e., less than 15%) for the forecast day.
 Forecast Discussion

   ZCZC SPCSWOD48 ALL
   ACUS48 KWNS 010853
   SPC AC 010853

   DAY 4-8 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0353 AM CDT FRI MAY 01 2015

   VALID 041200Z - 091200Z

   ...DISCUSSION...
   DISPARITY BETWEEN THE LATEST DETERMINISTIC GFS AND ECMWF...AND THEIR
   RESPECTIVE ENSEMBLE OUTPUT...INCREASES SUBSTANTIALLY BY THE EARLY TO
   MIDDLE PORTION OF NEXT WEEK CONCERNING DEVELOPMENTS WITHIN THE SPLIT
   WESTERLIES ACROSS WESTERN INTO CENTRAL NORTH AMERICA.  THIS LARGELY
   CENTERS ON A SIGNIFICANT CLOSED LOW/TROUGH WITHIN THE STRONGEST
   BRANCH...WHICH APPEARS LIKELY TO APPROACH THE BRITISH
   COLUMBIA/PACIFIC NORTHWEST COAST BY 12Z MONDAY.  BOTH SETS OF
   GUIDANCE ARE SIMILAR WITH THE GRADUAL INLAND PROGRESSION ACROSS THE
   COAST BY EARLY TUESDAY...BEFORE DIVERGING CONSIDERABLY THEREAFTER. 
   THE GFS/NCEP MREF SUGGEST THAT THE BULK OF THIS PERTURBATION
   SUBSEQUENTLY DIGS INTO A WEAKER SOUTHERN STREAM...ACROSS PARTS OF
   THE GREAT BASIN/COLORADO PLATEAU THROUGH THE REMAINDER OF THE
   PERIOD...WHILE THE ECMWF/ECENS SUGGEST THAT THE PRIMARY PORTION
   CONTINUES EASTWARD WITHIN THE NORTHERN STREAM...GENERALLY NEAR/NORTH
   OF THE WESTERN AND CENTRAL CANADIAN/U.S. BORDER.

   THE MODELS ARE FAIRLY SIMILAR CONCERNING A LEAD SOUTHERN STREAM
   IMPULSE...WHICH IS FORECAST TO PIVOT EAST NORTHEAST OF THE SOUTHERN
   ROCKIES THIS COMING TUESDAY.  THIS SHOULD BE ACCOMPANIED BY
   STRENGTHENING DEEP LAYER SOUTH TO SOUTHWESTERLY FLOW ACROSS PARTS OF
   THE SOUTHERN PLAINS...WHICH COULD SUPPORT SOME INCREASE IN SEVERE
   STORM POTENTIAL.  HOWEVER...CONSIDERABLE QUESTION EXISTS CONCERNING
   POSSIBLE STABILIZATION OF MID-LEVEL LAPSE RATES BY WIDESPREAD
   CONVECTION BY THIS TIME ACROSS THIS REGION...AND THE IMPACTS ON
   POTENTIAL INSTABILITY.

   SEVERE WEATHER PROBABILITIES REMAIN BELOW 15 PERCENT THROUGH THE
   EXTENDED PERIOD...DUE TO RELATIVELY LOW POTENTIAL FOR THE SEASON
   INTO THE EARLY PORTION OF NEXT WEEK...AND INCREASING  PATTERN
   PREDICTABILITY ISSUES THROUGH THE REMAINDER OF THE PERIOD.

   ..KERR.. 05/01/2015

   CLICK TO GET WUUS48 PTSD48 PRODUCT
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Page last modified: May 01, 2015
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