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371
ACUS48 KWNS 271156
SWOD48
SPC AC 271155

DAY 4-8 CONVECTIVE OUTLOOK RESENT 1
NWS STORM PREDICTION CENTER NORMAN OK
0655 AM CDT WED AUG 27 2014

VALID 301200Z - 041200Z

...DISCUSSION...
MEDIUM-RANGE MODELS IN DECENT AGREEMENT THROUGH DAYS 4-5 /THE
UPCOMING WEEKEND/ IN PROGRESSING A LARGE UPPER TROUGH EWD ACROSS THE
ROCKIES WITH TIME...IN THE WAKE OF AN INITIAL/WEAKENING TROUGH
EXPECTED TO BE SHIFTING INTO THE ERN CONUS.  SOME SEVERE RISK
APPEARS POSSIBLE DAY 4 /SAT 8-30/ ACROSS THE NRN PLAINS
VICINITY...AS STRONGER/DIFFLUENT UPPER FLOW SPREADS ACROSS THIS AREA
IN ADVANCE OF THE APPROACHING UPPER SYSTEM.  HOWEVER...ATTM IT
APPEARS THAT SEVERE POTENTIAL MAY REMAIN SOMEWHAT LIMITED/ISOLATED
DUE TO RELATIVELY MODEST LOW-LEVEL MOISTURE/AIRMASS INSTABILITY.

GREATER RISK APPEARS EVIDENT DAY 5 /SUN 8-31/...AS THE TROUGH
CONTINUES ITS EWD ADVANCE...SPREADING ENHANCED MID-LEVEL SWLYS
ACROSS THE PLAINS STATES.  AS A WELL-DEFINED COLD FRONT MOVES ACROSS
THE PLAINS...BOTH THE GFS AND ECMWF DEPICT SECONDARY LEE
CYCLOGENESIS ALONG THE BOUNDARY OVER THE CENTRAL HIGH PLAINS
VICINITY.  WITH BACKED LOW-LEVEL FLOW E/NE OF THIS FEATURE BENEATH
THE INCREASING SWLYS ALOFT...SHEAR FAVORABLE FOR SUPERCELLS IS
EXPECTED.  THIS COMBINED WITH RICHER BOUNDARY LAYER MOISTURE -- AND
THUS MORE SUBSTANTIAL DESTABILIZATION POTENTIAL -- WOULD SEEM TO
SUPPORT AN AREA FOR ENHANCED RISK OF SEVERE STORMS CENTERED INVOF
THE MID MO VALLEY DURING THE AFTERNOON...AND THEN SPREADING ENEWD
TOWARD THE UPPER MS VALLEY THROUGH THE EVENING.

MODEL DIFFERENCES BEGIN TO BECOME APPARENT DAY 6...AND THIS COMBINED
WITH THE LIKELIHOOD FOR RELATIVELY WIDESPREAD CONVECTION ONGOING
EARLY IN THE DAY PRECLUDE AREAL HIGHLIGHTS FOR SEVERE RISK BEYOND
DAY 5.

..GOSS.. 08/27/2014




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