Prognostic Meteorological Discussion
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FXAK02 KWNH 041824
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
223 PM EDT SAT JUL 04 2015

VALID 12Z WED JUL 08 2015 - 12Z SUN JUL 12 2015

...PATTERN HIGHLIGHTS AND GUIDANCE/UNCERTAINTY ASSESSMENTS...

WPC ALASKAN MEDIUM RANGE SURFACE FRONTS/PRESSURES AND 500 MB PROGS
ALONG WITH ASSOCIATED SENSIBLE WEATHER GRIDS HAVE BEEN PRIMARILY
DERIVED FROM A COMPOSITE BLEND OF THE 06 UTC GEFS MEAN AND 00 UTC
NAEFS/ECMWF ENSEMBLE MEANS AFTER ALASKAN WFO COORDINATION...BUT
DID MANUALLY ADJUST TOWARD THE DETERMINISTIC 00 UTC ECMWF DAY 4 /
WEDNESDAY TO BEST MAINTAIN WPC CONTINUITY. THE OVERALL PATTERN
EVOLUTION OFFERS AVERAGE PREDICTABILITY AND FEATURES A CLOSED MEAN
LOW CENTERED ALOFT OVER THE W-CENTRAL BERING SEA WHOSE LESS
CERTAIN EJECTING IMPULSES AND ATTENDANT SURFACE LOWS/WIDESPREAD
DAILY PCPN FOCUS INCREASINGLY WORK OVER TIME DOWNSTREAM AND INLAND
INTO ALASKA AND THE GULF OF AK AS AN AMPLIFIED LEAD MID-UPPER
LEVEL RIDGE GRADUALLY WEAKENS. OPTED TO SHY AWAY FROM
DETERMINISTIC MODEL GUIDANCE BEYOND MIDWEEK AFTER CONSIDERATION OF
POOR RUN TO RUN CONTINUITY AND MUCH LESS CLEAR SYSTEM SUPPORT. THE
LESS DETAILED WPC RESULTANT FIELDS DOWNPLAY LESS PREDICTABLE
SMALL-MID SCALE FORECAST COMPONENTS...BUT DO OFFER SOME CONTINUITY
CHANGES LATE WEEK INTO NEXT WEEKEND COMPARED TO YESTERDAYS PROGS.

SCHICHTEL

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