Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS48 KWNS 270901
SWOD48
SPC AC 270900

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0400 AM CDT FRI MAY 27 2016

VALID 301200Z - 041200Z

...DISCUSSION...
AMPLIFIED FLOW REGIME WILL REMAIN CONFINED PRIMARILY TO THE NORTHERN
TIER OF STATES AND SOUTHERN CANADA THROUGH NEXT WEEK.  THE 27/00Z
ECMWF/GFS DIFFER IN THE EASTWARD PROGRESSION OF A SHORTWAVE TROUGH
THROUGH THIS FLOW REGIME FROM DAY 4/MON THROUGH DAY 5/FRI...WITH THE
ECMWF FASTER THAN THE GFS.

DAY 4/MON...ALTHOUGH THE AFOREMENTIONED TIMING DIFFERENCES OF THE
SHORTWAVE BEGIN ON DAY 4...ECMWF/GFS AGREE WITH THE POTENTIAL FOR
ORGANIZED STORM DEVELOPMENT ACROSS WESTERN/CENTRAL SD INTO ADJACENT
PORTIONS OF SOUTHERN ND AND NORTHWEST NEB MONDAY AFTERNOON.
MOISTURE RETURN INTO THIS REGION WILL AID IN MODERATE INSTABILITY
WITH BULK SHEAR SUPPORTING STRONG TO SEVERE STORMS.  ISOLATED STRONG
TO SEVERE STORMS WILL BE POSSIBLE WITH SOUTHWARD EXTENT ALONG THE
DRYLINE...BUT THE LACK OF STRONGER FORCING ALOFT SHOULD LIMIT THE
COVERAGE SOUTHWARD FROM SD AND NORTHWEST NEB.

BEYOND DAY 4...MODELS DIFFER TOO MUCH WITH THE EASTWARD PROGRESSION
OF THE SHORTWAVE TROUGH THROUGH THE NORTHERN PLAINS TO GREAT LAKES
REGION.  ALTHOUGH STRONG TO SEVERE STORMS WILL BE POSSIBLE WITH THIS
TROUGH AS IT MOVES EAST DURING DAY 5/TUE TO DAY 8/FRI...UNCERTAINTY
IN THE PROGRESSION PRECLUDES THE INTRODUCTION OF SEVERE-WEATHER RISK
AREAS BEYOND DAY 4.

..PETERS.. 05/27/2016


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