Prognostic Meteorological Discussion
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FXUS02 KWBC 261601
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1200 PM EDT TUE MAY 26 2015

VALID 12Z FRI MAY 29 2015 - 12Z TUE JUN 02 2015

...PATTERN OVERVIEW...

AN ORGANIZED NRN STREAM MID-LEVEL CYCLONE LOCATED LATE WEEK OVER
WRN CANADA SHEARS EASTWARD ACROSS SRN CANADA INTO NEXT WEEK. THIS
OCCURS IN THE WAKE OF PASSAGE OF AN AMPLIFIED LEAD S-CENTRAL TO
ERN CANADIAN MID-UPPER LEVEL TROUGH. THIS TROUGH ALLOWS SURFACE
HIGH PRESSURE TO WORK DOWN ACROSS THE N-CENTRAL AND NERN US OVER
THIS FORECAST PERIOD...LINGERING OVER THE NERN US EARLY NEXT WEEK.

UNDERNEATH...A RIDGE ALOFT CENTERED OVER THE SOUTHEAST GRADUALLY
ERODES ALONG ITS NORTHWEST FLANKS DURING THIS MEDIUM PERIOD AS SRN
STREAM MID-UPPER LEVEL TROUGHING IS KICKED IN PIECES FROM THE WRN
US LATE WEEK OUT OVER THE PLAINS INTO THE E-CENTRAL US. AN
ASSOCIATED SURFACE LOW/WAVY FRONTAL SYSTEM AND WARM SECTOR
MESO-BOUNDARIES WILL PROVIDE AMPLE FOCUS FOR MULTIPLE ROUNDS OF
SHOWERS AND THUNDERSTORMS. SLOW OVERALL TRANSLATION AND
DEEP/SUSTAINED GULF THEN ATLANTIC MOISTURE FEED COULD FUEL REPEAT
CELLS WITH LOCALLY EXCESSIVE RAINFALL POTENTIAL.

WEST OF THE CONTINENTAL DIVIDE...UPPER-LEVEL RIDGING BEGINS TO
ANCHOR OVER THE DESERT SOUTHWEST AND A BROAD TROUGH TAKES SHAPE IN
THE ERN PACIFIC WITH AMPLIFIED MID-LEVEL TROUGH ENERGY MIGRATING
NORTHEASTWARD INTO THE NWRN/WRN US BY EARLY NEXT WEEK ON THE WRN
PERIPHERY OF THIS UPPER RIDGE ALONG WITH ANOTHER ROUND OF LATE
SEASON PCPN.

...UNCERTAINTY ASSESSMENT/MODEL PREFERENCES...

THE WPC MEDIUM-RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM A
COMPOSITE BLEND OF REASONABLY WELL CLUSTERED MID-LARGER SCALE
GUIDANCE FROM THE 06 UTC GFS/GEFS MEAN AND 00 UTC ECMWF/ECMWF
ENSEMBLE MEAN. THIS SCENARIO OFFER AVERAGE OR BETTER MID-LARGER
SCALE FLOW EVOLUTION PREDICTABILITY.

SCHICHTEL


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