Severe Storm Outlook Narrative (AC)
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ACUS03 KWNS 270742
SWODY3
SPC AC 270741

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0241 AM CDT FRI MAY 27 2016

VALID 291200Z - 301200Z

...THERE IS A MRGL RISK OF SVR TSTMS ACROSS LOWER MI...NORTHEAST
INDIANA AND NORTHWEST OH...

...THERE IS A MRGL RISK OF SVR TSTMS ACROSS MAINLY WESTERN PORTIONS
OF THE SOUTHERN AND CENTRAL PLAINS...

...SUMMARY...
ISOLATED STRONG TO SEVERE STORMS WILL BE POSSIBLE SUNDAY AFTERNOON
AND EVENING ACROSS LOWER MICHIGAN...NORTHEAST INDIANA AND NORTHWEST
OHIO.  ISOLATED STRONG TO SEVERE STORMS WILL ALSO BE POSSIBLE ACROSS
WESTERN PORTIONS OF THE SOUTHERN AND CENTRAL PLAINS.

...SYNOPSIS...
GENERALLY WEAK WESTERLY MIDLEVEL FLOW IS EXPECTED ACROSS THE
SOUTHERN HALF TO THREE QUARTERS OF THE U.S. THIS FORECAST
PERIOD...WHILE LOW-AMPLITUDE FLOW REGIME IS RELEGATED TO THE
NORTHERN TIER STATES.  A MIDLEVEL TROUGH WILL DEAMPLIFY AS IT TRACKS
FROM THE UPPER MS VALLEY THROUGH THE GREAT LAKES REGION ON SUNDAY.
AT THE SURFACE...AN ATTENDANT AREA OF LOW PRESSURE WILL TRACK FROM
NORTHWEST ONTARIO /NORTH OF NORTHERN MN/ TOWARD THE EAST-NORTHEAST
REACHING THE SOUTHERN EXTENT OF JAMES BAY BY 12Z MONDAY.

...LOWER MI/NORTHEAST INDIANA/NORTHWEST OH...
MOISTURE RETURN AHEAD OF AN EASTWARD-MOVING COLD FRONT WILL ALLOW
SURFACE DEW POINTS IN THE MID 60S TO REACH LOWER MI.  THIS COMBINED
WITH MIDLEVEL LAPSE RATES AROUND 7 C/KM AND SURFACE HEATING SUGGEST
MUCAPE UP TO 1500 J/KG SUNDAY AFTERNOON.  FORCING FOR ASCENT ALONG
THE TRACK OF THE MIDLEVEL TROUGH SHOULD ALLOW FOR THUNDERSTORM
DEVELOPMENT ALONG AND AHEAD OF THE COLD FRONT.  DESPITE MODERATE
INSTABILITY...MODEST BULK SHEAR OF 25-30 KT ORIENTED PARALLEL TO THE
SURFACE WIND SHIFT SUGGESTS LINE SEGMENTS WITH LOCALLY STRONG WINDS
AND/OR SOME HAIL WILL BE POSSIBLE.  IF BULK SHEAR IS EXPECTED TO BE
STRONGER IN LATER OUTLOOKS...THEN SOME OF THIS AREA MAY NEED TO BE
UPGRADED TO GREATER SEVERE PROBABILITIES.

...WESTERN PORTIONS OF THE SOUTHERN AND CENTRAL PLAINS...
MODERATELY STRONG INSTABILITY IS EXPECTED ACROSS THE SOUTHERN AND
CENTRAL PLAINS ON SUNDAY WITH MUCAPE RANGING FROM 2000-3000 J/KG.
ALTHOUGH WESTERLY 500-MB FLOW IS EXPECTED TO BE AT 20-30
KT...STRENGTHENING SOUTHERLY LOW-LEVEL FLOW - ESPECIALLY THROUGH
SUNDAY EVENING/NIGHT - WILL SUPPORT EFFECTIVE BULK SHEAR OF 35-40
KT.  THIS CAPE/SHEAR PARAMETER SPACE WOULD BE FAVORABLE FOR
ORGANIZED SEVERE STORMS.  HOWEVER...GIVEN THE WEAK FORCING FOR
ASCENT AND THE LACK OF FOCUSED SURFACE CONVERGENCE...THIS OUTLOOK
WILL INTRODUCE A RATHER BROAD MARGINAL SEVERE-WEATHER THREAT.  WITH
GENERALLY WEAK TO MODEST MIDLEVEL FLOW...STORMS THAT DO FORM COULD
FAVOR COLD-POOL DEVELOPMENT WITH STORMS PROPAGATING SOUTHWARD SUNDAY
EVENING/NIGHT.

...COASTAL CAROLINAS...
UNCERTAINTY IN THE DEVELOPMENT AND TRACK OF A TROPICAL/SUB-TROPICAL
SYSTEM INTO THE SOUTHEAST U.S. THIS WEEKEND PRECLUDES THE
INTRODUCTION OF SEVERE PROBABILITIES AT THIS TIME.

..PETERS.. 05/27/2016

$$



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