Prognostic Meteorological Discussion
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FXAK02 KWNH 241926
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
225 PM EST MON NOV 24 2014

VALID 12Z FRI NOV 28 2014 - 12Z TUE DEC 02 2014

LITTLE CHANGE IN THE NEW ALASKA MEDIUM RANGE FORECAST
PERIOD---DAYS 4-8. A COMPLEX LONG WAVE ALONG THE DATELINE THIS
MORNING---IS EXPECTED TO PARTIALLY BECOME ENTRAINED IN AN ARCTIC
FLOW OFF THE KAMCHATKA PENINSULA AND NORTHEAST SIBERIA. THE
SOUTHERN HALF OF THIS LONG WAVE TROUGH WILL SHEAR OUT ALONG AND
SOUTH OF THE ALEUTIANS AND MIGRATE DOWNSTREAM INTO THE WEST COAST
OF THE LOWER 48. THIS LEAVES BEHIND A BROAD CYCLONIC FLOW AND
UPPER-LEVEL TROUGH IN THE BERING SEA.

THE MODEL PREFERENCES WERE A COLLABORATION OF THE ALASKA WEATHER
FORECAST OFFICES IN ANCHORAGE AND JUNEAU TODAY. THIS
SOLUTION---THE 24/00Z ECENS ITS DETERMINISTIC RUN AND SOME GEFS
MEAN---WERE UTILIZED IN THE CURRENT 500MB AND SURFACE GRAPHICS
THROUGH 30/12Z. BY THE END OF DAY 6...THE GRAPHICS AND GRIDDED
DATA THEN TRANSITIONED TO A 70/30 ECENS-GEFS BLEND FOR DAYS 7-8.
THE GEFS IS A SLIGHTLY FASTER SOLUTION WITH THE ZONAL FLOW PATTERN
IN THE NORTH PACIFIC AND UPPER-LEVEL FLOW UNDERCUTTING THE BASE OF
THE BERING SEA TROUGH. BOTH MEANS (THE ECENS-GEFS) WERE NOT FAR
OFF AT ALL...WHICH ADDED CONFIDENCE THAT THE WAVE TRAIN DEVELOPING
OFF THE EAST ASIAN COAST WILL BE ONE THAT IS LOW-AMPLITUDE AND
FAST-MOVING IN NATURE.

VOJTESAK

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