Day 4-8 Severe Weather Outlook Issued on May 27, 2014
Updated: Tue May 27 08:57:03 UTC 2014
Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
D4
Fri, May 30, 2014 - Sat, May 31, 2014
D7
Mon, Jun 02, 2014 - Tue, Jun 03, 2014
D5
Sat, May 31, 2014 - Sun, Jun 01, 2014
D8
Tue, Jun 03, 2014 - Wed, Jun 04, 2014
D6
Sun, Jun 01, 2014 - Mon, Jun 02, 2014
(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 270855
SPC AC 270855
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0355 AM CDT TUE MAY 27 2014
VALID 301200Z - 041200Z
...DISCUSSION...
THE ECMWF AND GFS SOLUTIONS BEGIN THE DAY 4 TO 8 PERIOD WITH AN
UPPER-LEVEL RIDGE OVER THE MID TO UPPER MS VALLEY AND MOVE THIS
FEATURE SLOWLY EWD ON FRIDAY/DAY 4. STRONG TO SEVERE THUNDERSTORMS
WILL BE POSSIBLE ALONG A COLD FRONT IN THE NRN PLAINS ON THE BACK
SIDE OF THE UPPER-LEVEL RIDGE. HEIGHTS FALL ACROSS THE NRN AND CNTRL
PLAINS ON SATURDAY/DAY 5 AS SOUTHWEST MID-LEVEL FLOW BECOMES MORE
FIRMLY ESTABLISHED ACROSS THE REGION. ISOLATED STRONG TO SEVERE
THUNDERSTORMS WILL BE POSSIBLE FROM MT EWD ACROSS THE DAKOTAS WHERE
THE MODELS FORECAST LOW-LEVEL MOISTURE AND DEEP-LAYER SHEAR
SUFFICIENT FOR SEVERE STORMS. FURTHER TO THE EAST ACROSS THE UPPER
MS VALLEY ON SATURDAY...THE GFS AND ECMWF DIFFER WITH THE ECMWF
DEVELOPING NUMEROUS STORMS ALONG A TONGUE OF LOW-LEVEL MOISTURE
ACROSS MUCH OF MN. IF THIS SOLUTION WHERE TO VERIFY...THEN A
SUBSTANTIAL SEVERE THREAT COULD DEVELOP ACROSS THE UPPER MS VALLEY
SATURDAY AFTERNOON WITH SUPERCELLS AND POSSIBLY TORNADOES.
HOWEVER...THE GFS IS LESS AGGRESSIVE ON SATURDAY SUGGESTING THIS
POTENTIAL IS UNCERTAIN. ON SUNDAY/DAY 6...THE MODELS MOVE AN
UPPER-LEVEL TROUGH INTO THE INTERMOUNTAIN WEST WITH SOUTHWEST
MID-LEVEL FLOW REMAINING OVER THE CNTRL AND NRN PLAINS. SEVERE
THUNDERSTORMS COULD AGAIN DEVELOP IN THE NRN PLAINS SUNDAY
AFTERNOON. ON MONDAY/DAY 7...CONSIDERABLE DIFFERENCES EXIST IN THE
ECMWF AND GFS SOLUTIONS. THIS MAKES PREDICTABILITY LOW FOR THE
SEVERE THREAT POTENTIAL ON MONDAY. ATTM...WILL NOT ADD A SEVERE
THREAT AREA IN THE UPPER MS VALLEY FOR SATURDAY/DAY 5 DUE TO
DIFFERENCES IN THE MODEL SOLUTIONS.
..BROYLES.. 05/27/2014
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