Prognostic Meteorological Discussion
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FXAK02 KWNH 011838
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
238 PM EDT SUN MAY 01 2016

VALID 12Z THU MAY 05 2016 - 12Z MON MAY 09 2016

TODAY`S ALASKA MEDIUM RANGE FORECAST...GRID FILES AND MASS FIELD
GRAPHICS WERE COMPRISED OF A 40/30/30 BLEND OF THE ENSEMBLE MEANS
--- THE 1/00Z GEFS ... THE 00Z NAEFS AND THE 30/12Z ECENS
RESPECTIVELY.

THE ADJUSTMENTS MADE TO THE FORECAST WERE MINIMAL EAST OF 160W
LONGITUDE BETWEEN DAY 4-6 ... AND THERE WILL BE PERSISTENT
SOUTHWEST COMPONENT TO THE MID-LEVEL FLOW --- WHICH --- FOR ALL
INTENTS AND PURPOSES --- WILL GRADUALLY ERODE THE UPPER-LEVEL
RIDGE AXIS --- LOCATED OVER WESTERN CANADA. AND MORE IMPORTANTLY
... CREATE A MUCH WETTER PATTERN ALONG THE WEST COAST OF CANADA
AND ALASKA PANHANDLE.

WHAT TRANSPIRES WEST OF 160W LONGITUDE AFTER DAY 6 --- SEEMED TO
BE INFLUX... WITH RESPECT TO STORM TRACK. ONCE THE RIDGE
ERODES...THERE SHOULD BE A WESTERLY FLOW THAT BRIEFLY SWEEPS
ACROSS THE EASTERN ALEUTIANS AND WESTERN GULF OF ALASKA. A BREAK
FROM MODERATE AND INTENSE PRECIPITATION...TO MORE OF A BENIGN
PERIOD OF WEATHER. THE DURATION OF THE BENIGN WEATHER --- WILL
GIVE HIGH PRESSURE A CHANCE TO REBUILD ACROSS THE INTERIOR AND
PORTIONS OF THE GULF OF ALASKA.

THE QUESTION AND FORECAST CHALLENGE IS --- HOW SOON WILL ANOTHER
ORGANIZED SURFACE CYCLONE MIGRATE ALONG 50N LATITUDE? --- EAST OF
THE DATELINE --- AND HOW SOON WILL ITS EFFECTS --- BEGIN TO ALTER
THE DOWNSTREAM PATTERN OVER THE GULF?

THE CURRENT ENSEMBLE MEANS SUGGEST A FLATTER--- MORE ZONAL BUT
MUCH FASTER FLOW PATTERN ALOFT --- REQUIRING MORE DISCERNMENT AND
CREATING A CHALLENGE WITH THE SEQUENCING AND SPACING OF A NORTH
PACIFIC MIGRATORY SHORTWAVE STORM TRACK --- AT THE DAY 7+ TIME
SCALE.

VOJTESAK

$$





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