Severe Storm Outlook Narrative (AC)
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112
ACUS48 KWNS 260851
SWOD48
SPC AC 260849

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0349 AM CDT FRI AUG 26 2016

VALID 291200Z - 031200Z

...DISCUSSION...
THE MEDIUM RANGE MODELS INCLUDING THE ECMWF AND GFS BEGIN THE DAY 4
TO 8 PERIOD WITH A ZONAL FLOW PATTERN OVER THE NRN UNITED STATES. ON
MONDAY/DAY 4...THE MODELS DEVELOP AN UPPER-LEVEL RIDGE OVER THE NRN
HIGH PLAINS MOVE THIS FEATURE SLOWLY EWD ACROSS THE NRN PLAINS ON
TUESDAY/DAY 5. AT THE SFC...BOTH SOLUTIONS MOVE A COLD FRONT SEWD
ACROSS THE NRN PLAINS ON MONDAY AND SHOW A POCKET OF INSTABILITY IN
ERN PARTS OF THE NRN PLAINS EWD INTO THE UPPER MS VALLEY. AN AXIS OF
INSTABILITY IS FORECAST TO DEVELOP IN THE NRN PLAINS TUESDAY.
INFLUENCE FROM THE UPPER-LEVEL RIDGE SHOULD KEEP CONVECTION ISOLATED
ACROSS THE REGION WITH A MARGINAL SEVERE THREAT POSSIBLE ALONG
CORRIDORS OF THE INSTABILITY THAT DEVELOP.

ON WEDNESDAY/DAY 6 AND THURSDAY/DAY 7...THE GFS AND ECMWF SOLUTIONS
BEGIN TO DIVERGE BUT BOTH SOLUTIONS SUGGEST THAT THE UPPER-LEVEL
RIDGE WILL REMAIN OVER THE NCNTRL STATES. THE ECMWF DEVELOPS AN AXIS
OF INSTABILITY IN THE GREAT PLAINS WHILE THE GFS HAS THE SAME
FEATURE EXCEPT A BIT FURTHER TO THE EAST. ISOLATED MARGINALLY SEVERE
THUNDERSTORMS WILL AGAIN BE POSSIBLE WEDNESDAY AFTERNOON AND
THURSDAY AFTERNOON ALONG THE CORRIDOR OF STRONGEST INSTABILITY. ON
FRIDAY/DAY 8...BOTH SOLUTIONS MAINTAIN A SIMILAR UPPER-LEVEL PATTERN
BUT DIVERGE EVEN MORE ON THE DETAILS. THIS WOULD AGAIN MAKE A
MARGINAL SEVERE THREAT POSSIBLE IN THE NCNTRL STATES ON FRIDAY
AFTERNOON BUT UNCERTAINTY REMAINS SUBSTANTIAL LATE IN THE PERIOD.

..BROYLES.. 08/26/2016



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