Prognostic Meteorological Discussion
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FXAK02 KWNH 251852
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
152 PM EST THU DEC 25 2014

VALID 12Z MON DEC 29 2014 - 12Z FRI JAN 02 2015

ACTIVE TROUGH IS ANTICIPATED IN THE WESTERN BERING SEA AND
ALEUTIANS THIS ALASKA MEDIUM RANGE. A RELEASE OF ARCTIC AIR INTO
THE LOWER 48 SPREADS WESTWARD ACROSS THE PANHANDLE AND INTO THE
FAR EASTERN/NORTHEASTERN GULF OF ALASKA AND HIGH PRESSURE PREVAILS
ALONG 120W-130W FROM THE ARCTIC CIRCLE SOUTHWARD INTO THE PACIFIC
NORTHWEST STATES---WASHINGTON/OREGON.

THE 25/00Z ECENS MEAN AND 25/006Z GEFS MEAN DO A GOOD JOB OF
REPRESENTING THESE TWO SYNOPTIC-SCALE FEATURES THROUGH THE ALASKA
MEDIUM RANGE PERIOD...AND FOR SOME OF THE SURFACE GRAPHIC
DETAILS---WPC UTILIZED THE 25/00Z DETERMINISTIC TO HANDLE THE
SUBTLE PROGRESSION OF THE LOW-LEVEL FLOW AND WEAK SURFACE
STATIONARY FRONT DEVELOPING OVER THE GULF OF ALASKA---THE RESULT
OF COLD CANADIAN AIR SPILLING ACROSS THE PANHANDLE AND
`DEPOSITING` IN THE EASTERN GULF OF ALASKA.

THE SUBTLE `KEY` IN THE MEDIUM RANGE PATTERN---IS THE
NORTHEASTWARD PROGRESSION OF THE UPPER-LEVEL TROUGH AND ITS
`ABILITY` TO EJECT MID-LEVEL ENERGY---SOUTHEASTWARD---ACROSS THE
SOUTHEAST BERING...EASTERNMOST ALEUTIANS AND INTO THE NORTHWEST
GULF OF ALASKA.

VOJTESAK

$$





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