Prognostic Meteorological Discussion
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000
FXAK02 KWNH 221801
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
201 PM EDT MON SEP 22 2014

VALID 12Z FRI SEP 26 2014 - 12Z TUE SEP 30 2014

THE LARGER-SCALE PATTERN SHOWS ENERGETIC AND POTENTIALLY UNSTABLE
FLOW CONTINUING ACROSS THE NORTHERN PACIFIC THROUGH DAY 8 WITH
LARGE AND POSSIBLY DEEP LOWS FORMING NEAR OR JUST WEST OF THE
ALEUTIANS BEFORE TRACKING INTO THE GULF OF ALASKA AND WEAKENING.
THE SPREAD IS MODEST FOR THIS PARTICULAR PATTERN WITH UNCERTAINTY
CONTRIBUTED FROM SOME TROPICAL REMNANTS OVER THE SOUTHWEST PACIFIC
AS WELL AS THE NORTHERN STREAM ACROSS PORTIONS OF RUSSIA INTO THE
ARCTIC OCEAN.  BETWEEN THESE DIFFERING STREAMS...AN ELONGATED AND
PERSISTENT MID/UPPER HIGH IS EXPECTED TO PREVAIL...WHICH INCLUDES
MUCH OF THE MAINLAND.  THE MODEL WHICH CLUSTERS BEST AND ALIGNS
WITH THE ENSEMBLE MEAN IS THE 00Z ECMWF...ALTHOUGH SOME ASPECTS OF
THE GFS/CANADIAN/UKMET ALSO AGREE EARLY IN THE PERIOD AND COULD BE
USED ALBEIT MORE CAUTIOUSLY.  FOR BLENDING PURPOSES HOWEVER...USED
A COMPOSITE OF CONTINUITY WITH ABOUT 20 PERCENT EACH GEFS
MEAN/NAEFS MEAN/ECMWF ENSEMBLE MEAN...WITH SOME MANUAL ADJUSTMENTS
INCLUDED AT THE END.  THIS PATTERN FAVORS WET CONDITIONS FOR THE
SOUTHERN MAINLAND AS WELL AS PORTIONS OF THE ALEUTIANS...WHILE
GENERALLY DRY CONDITIONS PERSIST TO THE NORTH.

JAMES

$$




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