Prognostic Meteorological Discussion
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FXAK02 KWNH 161826
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
225 PM EDT TUE SEP 16 2014

VALID 12Z SAT SEP 20 2014 - 12Z WED SEP 24 2014

WPC ALASKAN MEDIUM RANGE SURFACE FRONTS/PRESSURES AND 500MB PROGS
ALONG WITH ASSOCIATED SENSIBLE WEATHER GRIDS HAVE BEEN PRIMARILY
DERIVED FROM A BLEND OF COMPATABLE GUIDANCE FROM THE 00 UTC
GFS/ECMWF/NAEFS ENSEMBLE MEANS. RECENT DETERMINISTIC MODELS OFFER
SOME CLUES TO EMBEDDED SYSTEM TRENDS...BUT OVERALL SEEM TOO RUN TO
RUN INCONSISTENT.

RECENT DETERMINISTIC GFS AND ECMWF MODEL RUNS HAVE BEEN ROBUST BUT
QUITE RUN TO RUN INCONSISTENT WITH TIMING/POSITION OF MID-UPPER
LEVEL TROUGH ENERGY DIGGING FROM THE ARCTIC INTO THE ALASKAN
INTERIOR THIS WEEKEND INTO NEXT WEEK...ANY POTENTIAL INTERACTION
WITH MORE SRN STREAM BASED FLOW. WATER VAPOR IMAGERY UPSTREAM FROM
NERN ASIA INTO THE ARCTIC LENDS SOME SUPPORT FOR HIGH LATITUDE
AMPLIFICATION...BUT ABOVE AVERAGE FORECAST SPREAD WITH THE FEATURE
MAY BEST PORTEND AN ENSEMBLE MEAN APPROACH FOR NOW...EVEN WITH
POTENTIAL. THE ENSEMBLE MEAN BLEND BY NATURE SHOWS LESS ROBUST BUT
COOLING MEAN MID-UPPER LEVEL INTERIOR TROUGH DEVELOPMENT.

AMPLE MID-UPPER LEVEL TROUGHING SETTLES OVER THE GULF OF ALASKA
INTO THIS WEEKEND IN AMPLIFIED MID-UPPER LATITUDE FLOW THAT SHOULD
FAVOR HEAVIER PRECIPITATION FROM SRN TO SERN AK. THIS ENERGY AND
WEATHER/QPF FOCUSING LOW BECOMES REPLACED NEXT WEEK BY UPSTREAM
NRN PACIFIC KICKER ENERGIES. IN THIS PATTERN...WELL ORGANIZED LOW
ENERGY AND WEATHER FOCUS SINKS SEWD FROM THE WRN ALEUTIANS THIS
WEEKEND TO REACH THE GULF OF ALASKA BY EARLY-MID NEXT
WEEK...FEEDING ENERGY INTO A RENEWED MEAN TROUGH POSITION THAT
LEADS TO A THREAT FOR NEW DEEP GULF OF ALASKA CYCLOGENESIS IN
ABOUT A WEEK.

SCHICHTEL

$$




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