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269
FXAK02 KWNH 211921
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
321 PM EDT TUE OCT 21 2014

VALID 12Z SAT OCT 25 2014 - 12Z WED OCT 29 2014

THE WPC ALASKAN MEDIUM RANGE FORECAST MAINTAINED AN ENSEMBLE MEAN
FORECAST APPROACH AS RECENT DETERMINISTIC MODELS OFFER SOME OF THE
WORST RUN TO RUN CONTINUITY AND FORECAST SPREAD IN RECENT MEMORY.
THIS MAY BE RELATED IN SOME WAY TO AN ONGONG SATELLITE INJEST
PROBLEM...BUT THAT IS NOT CONFIRMED. AFTER
COORDINATION/COLLABORATION WITH LOCAL WFO`S DECIDED TO DERIVE THE
WPC MEDIUM RANGE PRODUCT SUITE PRIMARILY FROM THE 06 UTC GEFS MEAN
THAT OFFERS MODEST WPC CONTINUITY WITH AN OVERALL NEAR COMPOSITE
GFS GUIDANCE SOLUTION WHILE TRENDING TOWARD MORE AMPLIFIED
MID-UPPER LATITUDE FLOW.

SUFFICE TO SAY THAT THIS REMAINS A VERY LOW CONFIDENCE FORECAST
FOR MOST WEATHER ASPECTS...BUT FEEL GOOD AT LEAST ABOUT
DOWNPLAYING GUIDANCE FROM AN OUTLIER 00 UTC ECMWF RUN WITH RESPECT
TO TOO ROBUSTLY BRINGING THE ESSENCE OF AN EXTRATROPICAL LOW
ASSOCIATED WITH CURRENT CENTRAL PACIFIC TROPICAL STORM ANA UP INTO
THE GULF OF AK THROUGH UNFAVORABLE FLOW AS SHOWN BY WATER VAPOR
ETC. THIS WPC SOLUTION INSTEAD STILL IMPORTANTLY LIMITS TROPICAL
MOISTURE ASSOCIATED WITH ANA REACHING THE NORTH CENTRAL GULF IN
LUE OF DIRECTING THE BULK OF THE TROPICAL CONNECTION INTO WRN
CANADA AND POINTS SOUTH. THE 12 UTC ECMWF HAS STRONGLY TRENDED
THIS SIGNIFICANT THREAT IN THIS DIRECTION.

SCHICHTEL


$$






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