Prognostic Meteorological Discussion
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FXAK02 KWNH 251820
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ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
219 PM EDT FRI JUL 25 2014

VALID 12Z TUE JUL 29 2014 - 12Z SAT AUG 02 2014

THE MEDIUM-RANGE MODELS AND ENSEMBLES CONTINUE TO HIGHLIGHT
ANCHORING OMEGA BLOCKING COMPRISED OF SLOW MOVING AND UNSETTLING
CLOSED MEAN LOWS CENTERED SOUTH OF THE WRN ALEUTIANS AND OVER THE
GULF OF ALASKA THAT BOOKEND AN AMPLIFIED RIDGE EXTENDING NORTHWARD
THROUGH THE CENTRAL ALEUTIANS TO ACROSS THE BERING SEA. THIS
PATTERN FAVORS WRAPPING PCPN UP INTO THE W-CENTRAL ALEUTIANS WITH
MODERATE AMOUNTS MORE LIKELY INTO COASTAL SRN AND SERN ALASKA
TERRAIN.  RIDGE AMPLITUDE MEANWHILE FAVORS SOME COOLING NRN STREAM
TROUGHING AND GENERALLY LIGHT PCPN FROM THE ARCTIC DOWN INTO THE
N-CENTRAL INTERIOR.

THE 06 UTC GFS/GFS ENSEMBLE MEAN AND 00 UTC ECMWF AND ECMWF/NAEFS
ENSEMBLE MEAN SEEM REASONABLY COMPATABLE AND OFFER GOOD CONTINUITY
TO ALLOW WPC PREFERENCE FOR A COMPOSITE BLEND SOLUTION INTO DAY 6
THU. JUST THESE ENSEMBLES WERE UTILIZED AFTER THEN INTO DAY 8 IN A
PERIOD OF GRADUALLY INCREASING DETERMINISTIC MODEL VARIANCE. THIS
BLEND ALONG WITH SOME  FORECASTER MODIFICATIONS MAINTAIN DECENT
OCEANIC SURFACE LOW DEPTHS THROUGH THE PERIOD CONSISTENT WITH
FAVORABLE DYNAMIC SUPPORT ALOFT.  THIS BLEND ALSO PROVIDES SOME
SMALLER SCALE DETAIL CONSISTENT WITH OTHERWISE ABOVE NORMAL
PREDICTABILITY IN AN AMPLIFIED PATTERN WITH BELOW NORMAL FORECAST
SPREAD.  THIS BLEND WAS USED AS A BASIS FOR PRODUCTION OF THE
ENTIRE WPC ALASKAN MEDIUM-RANGE FORECAST PRODUCT SUITE. THESE WELL
CLUSTERED MODEL CHOICES REPRESENT SOLUTIONS ON THE SLIGHTLY MORE
AMPLIFIED AND PERSISTENT SIDE OF THE FULL ENVELOPE OF SOLUTIONS
CONSISTENT WITH THE BLOCKY PATTERN NATURE.

SCHICHTEL

$$




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