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FXAK69 PAFG 242144
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
144 PM AKDT Sat Aug 24 2019

.SYNOPSIS...
A strong low in the high Arctic with a cold front stretching
southwest along the Arctic Coast of Alaska will move east with the
front stretching out over the Brooks Range. West winds 20kt
across the Arctic Coast from Utqiagvik east will weaken slowly
tonight as the front moves south. This front will bring mixed rain
and snow to higher elevations of the Brooks Range and may see
accumulations above 4000 ft, while the SE Interior has isolated
showers.

A second low in NE Russia will move east across the Chukchi Sea
Mon, and then track east across the Brooks Range Mon night and
Tue. This will bring more rain and snow to the Brooks Range, with
snow possibly accumulating above 4000 ft.

Aloft...
The long wave pattern consists of a deep long wave trough that
stretches from the high Arctic south over Mainland Alaska and into
the Gulf of Alaska and a long wave ridge over the NW Pacific and
the Bering Sea. The pattern becomes progressive with the ridge
building over southern Alaska Mon through Wed. This is causing
westerly flow over Northern Alaska with a series of short waves
moving east across the northern part of the state. This will keep
the Interior mainly dry for the next several days, while it
remains wet from the Brooks Range north.

The ridge over southern Alaska starts to break down next weekend
with flow turning more SW. For most of Nrn Alaska this means near
normal temperatures and scattered showers trending towards cooler
next weekend, and remaining wet over West Coast of Alaska.

A short wave trough extending from Inuvik to Northway will move
east tonight. There are scattered showers with this that will end
tonight.

A second short wave over NW Alaska will move to Anaktuvuk Pass to
the the Yukon Delta, by 4am Sun, to Arctic Village to Bethel by
4pm Sun, to Old Crow to Denali by 4am Mon, then to Dawson to
Northway by 4pm Mon. Expect isolated showers along this trough
over the West Coast and Interior as it moves east.

A third short wave trough over Eastern Russia will move east to
the West Coast of Alaska by 4pm Mon, to Barrow to Bethel by 4am
Tue, and Barter Island to McGrath by 4pm Tue. Expect another batch
of Isolated showers over the Interior with this. This trough will
induce a surface low over the Chukchi Sea Mon that will move east
along the Brooks Range with the trough Mon night and Tue. Will
address that weather in the surface section below.

Surface...
A 984 mb low 500 NM north of Demarcation Point will move east
tonight. A cold front stretching west from this low will move to
Banks Island to Barter Island to Utqiagvik the west by 3am Sun,
then to Inuvik to Point Lay and west by 4pm Sun, then move along
the Brooks Range by 4am Mon and remain quasi-stationary into Tue.
Expect rain and fog along and south of the front, with snow mixed
with rain above 3000 ft in Brooks Range, and all snow above 4000
ft in the Brooks Range. Could see 1-2 inches accumulation each 12
hr period above 4000 feet in the Brooks Range over the next
several days. Expect much of the snow to melt during the day time.
There are west winds 20-25 kt along the front now that will drop
to 10-20kt on Sun.

A low developing along the front in NE Russia by 4am Mon, will
move to 200 NM west of Point Hope as a 1003 mb low by 4am Mon,
then to 100 NM west of Point Hope as a 1005 mb low by 4pm Mon,
to Anaktuvuk Pass as a 1007 mb low by 4am Tue, and to Arctic
Village as a 1006 mb low by 4pm Tue. Expect -25-.40 inch of rain
with this low center Mon night and Tue, with mixed rain and snow
above 3000 ft, and 1-2 inches of snow above 4000 ft. This will
cause winds to turn N 10-15 kt over the Arctic Coast Mon into Tue,
and Southwest 20-25kt over the West Coast Mon night into Tue.

&&

.DISCUSSION...
Models initialize well aloft and in general agreement through 4pm
Mon. After that time, the ECMF and Canadian models bring a
strong short wave east across the North Slope, while the GFS and
NAM keep the short wave farther NW over the Chukchi Sea. At this
time favor the GFS and NAM as they drop some of the short wave
energy south into the long wave trough over Eastern Russia, while
the ECMF and Canadian take most of the energy east.

For precipitation, favor the GFS for the broader areal coverage
over the Interior, but in the Interior this will be the areal
coverage of low probability showers and be isolated to scattered.


At the surface at 15Z, models verify well and show similar
solutions through 4am Mon. After that time, the NAM is at least 6
mb deeper than the GFS and ECMF with a low moving east across the
North Slope. At this time we favor the GFS and ECMF which keep
this low weaker, and track it east across the Brooks Range on Mon
night and Tue.

Bottom line is, we favor the GFS for winds everywhere, and favor
the GFS for areal coverage of low probability showers over the
Interior.


Coastal Hazard Potential Days 3 and 4...
Elevated surf along the Arctic Coast will diminish tonight as
winds drop off.
Could see slightly elevated surf along the West Coast Mon night
into Tue night.

&&

.FIRE WEATHER...
Temps will be in the 50s and lower 60s, with Min RH 35-45%, over
the next several days. Winds above 15 mph not expected until Mon
PM. No thunderstorms expected.

&&

.HYDROLOGY...
River levels remain high but slowly falling across Interior.
River may be rising slightly over the North Slope next week.
Ground water levels remain high for much of the next week.
Most precipitation next week will be from the Brooks Range north.
Caution should be used on all waterways in the interior as trees
and other debris will continue to move downstream.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory for PKZ240-PKZ245.
&&

$$

JB AUG 19
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