Area Forecast Discussion
Issued by NWS Fairbanks, AK

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FXAK69 PAFG 252023

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
1223 PM AKDT WED MAY 25 2016


Current runs of the GFS/NAM/ECMWF models are in good agreement
out through Saturday, building a strong upper level high over the
southwest interior by Thursday then indicating movement of the
high center to the Seward Peninsula by Saturday. The operational
500 mb forecasts runs are in good agreement with the GEFS and
ECMWF ensemble means. By the middle of next week the GEFS and
ECMWF ensemble mean 500 mb progs continue to be in good agreement,
indicating some weakening of the upper high with the center
drifting westward to near the Bering Strait. Maximum forecast
500mb heights in the high center are about 575 dam, much above
climatological normals for this time of year and probably not much
below monthly record heights over the west coast and southwest
interior. Current GEFS/GFS model runs become increasingly
divergent over northeast Alaska after the middle of next
week...with the ECMWF being more aggressive in bringing a cold
upper low southward to near Demarcation Point by Wednesday night.
The operational GFS and GEFS ensemble mean keep this upper low
much farther to the northeast, to near northern Banks Island by
late Wednesday night. The ECMWF ensemble mean also favors a
farther northward position of the upper low, keeping the mean
center several hundred miles northwest of Banks Island. That being
said, an average of the the GEFS and ECMWF ensemble means appears
to be the most reasonable forecast in later parts of the medium
range period, with the operational GFS not departing much from the
average of the two ensemble means at 500 mb. Along with the high
500 mb heights, 850 mb temperatures will also be above normal,
likely maxing out at around +10C or higher.

UPPER AIR AT 500 MB...A ridge extending from St Lawrence Island
to the western Alaska Peninsula and southward will continue to
build, with a 575 dam high developing over Bristol Bay by late
tonight, then moving to near or north of the Seward Peninsula by
late Sunday night. A short wave trough lying north-south across
the eastern Alaska interior will exit eastward into the Yukon
Territory by late tonight. As the strong upper level high builds,
the influx of moisture over much of northern Alaska will be
gradually cut off, bringing an end to the wet regime.

SURFACE...A weak 1017 mb low centered just west of Old Crow
will weaken into a trough by this evening. High pressure will
build over the western interior and west coast, with a 1027 mb
high center developing over the southwest interior by
Thursday morning, then moving to the Seward Peninsula by
late Wednesday night.

ARCTIC COAST...A mainly easterly wind flow pattern will continue
through Friday, with low stratiform cloud cover and areas of
fog continuing. The fog will likely be more widespread during
the nighttime and early morning hours, with visibility 1/4 mile
or less at times in some areas from the Barrow area east. Rain or
showers spreading to the western coastal areas and western
interior Arctic slope late tonight and Thursday morning, tapering
off by late Thursday night.

Rain or showers over most areas tonight, and over the northern
parts of the western interior and along the coast from the
northern Seward Peninsula northward on Thursday, as the building
ridge pushes the moisture flow northward. The rain will
rapidly taper off Thursday night as the upper high continues
to build. Mostly clear with much warmer temperatures Friday
into the weekend. High temperatures over most inland areas will
climb into the 70s Friday, with high temperatures in the 70s
likely continuing into the middle of next week. Coastal
temperatures will likely be influenced by onshore/offshore
wind flow.

Rain or showers continuing over much of the central and eastern
interior tonight, rapidly tapering off Thursday night as the
upper ridge builds and cuts off the supply of moisture. Warmer and
drier conditions developing Friday and continuing into the middle
of next week. Most interior areas will see high temperatures
ranging from the mid 60s to mid 70s.


Wet conditions will continue through Thursday, with rain or
showers rapidly tapering off Thursday night. A trend to much
warmer and drier conditions will begin Friday. Warmer and drier
conditions are expected to continue into the middle of next week,
with no chinook or southerly gap wind events expected in the
Alaska Range. Isolated thunderstorms are expected in parts
of the northeastern interior this afternoon and evening, and
activity that develops is likely to be minimal. No thunderstorms
are expected Thursday into the weekend. The airmass will become
vary stable over the weekend as high pressure aloft builds.


The flood watch for the Colville River Delta area has been
extended through noon Thursday. Water levels in that area
are expected to remain high.


Flood Watch for AKZ203.


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