257
FXAK69 PAFG 031443
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
643 AM AKDT Mon Jun 3 2024

.SYNOPSIS...A dynamic weather pattern is in place over Northern
Alaska as an Arctic trough drops south over the West Coast with
repeated shortwave troughs rotating into the central and eastern
Interior from the east. This is bringing a cooling trend to the
West Coast and western Interior, continued showers and
thunderstorms to the central and eastern Interior, and even snow
and possible mixed precipitation along a convergence zone between
these features from the central Brooks Range north to the Arctic
Coast. Snow and mixed precipitation on the North Slope will
diminish Tuesday night, but the rest of the area will see little
change. Wednesday appears to be the wettest day across the
Interior.

&&

.DISCUSSION...

Analysis and Model Discussion...An Arctic trough has begun its
trek south and now lies just offshore of Point Lay. A weak ridge
continues to extend southwest over the northeast Interior and
eastern Brooks Range from Canada. A convergence zone between these
two features continues to bring a mix of precipitation from the
central Brooks Range north along the Dalton Highway to Deadhorse.
Reports of 5 to 10 inches of snow near Toolik Field Station
through Sunday evening, though very little snow has accumulated at
Atigun Pass. This convergence zone will shift slightly to the west
through Monday, though precipitation will continue over much of
the same area. The best chance for freezing rain will be near
Deadhorse through mid morning today.

The Arctic trough will continue south as a closed low down to 700
mb to reach Norton Sound Monday afternoon, the Yukon Delta on
Monday night, and St. Paul Island on Wednesday afternoon.
Meanwhile in the Interior, a number of shortwave troughs will
rotate through the flow from the east, bringing showers and
thunderstorms. The strongest one appears to arrive on Wednesday,
bringing areas of heavy rain and potentially strong thunderstorms
to an area west of Fairbanks and east of Galena.

Models are in good agreement on the overall pattern and show
slight differences in the placement of precipitation. For this
forecast package we will increase PoPs on Tuesday afternoon and
overnight into Wednesday for the south slopes of the Brooks Range
and western North Slope as southerly upslope flow moves in behind
the convergence zone. We will increase PoPs across the Interior on
Wednesday afternoon with the arrival of the strong shortwave. We
will also expand the area and coverage of thunderstorms on
Wednesday afternoon and add in some southerly gap winds through
Alaska Range passes on Wednesday. With so many fine scale features
moving through the flow, confidence in precipitation placement is
not excellent, but expect some heavy showers each day across the
Interior.

Central and Eastern Interior...Summer conditions will continue
with showers and thunderstorms each afternoon and highs in the mid
60s to mid 70s. Little change is expected until Wednesday, when a
more robust shortwave moves into the area from the east. This will
bring more widespread showers that may be heavy at times. South winds
though Alaska Range Passes will gust to around 30 mph on Wednesday
morning as this shortwave moves west.

West Coast and Western Interior...Gale force northerly winds
continue through the Bering Strait as an Arctic trough drops south
over the area. Much cooler temperatures are expected across the
entire region today, with slight warming on Tuesday and Wednesday.
Showers and thunderstorms are expected each afternoon mainly east
of Galena. Elsewhere, partly cloudy to mostly clear skies are
expected.

North Slope and Brooks Range...Light snow with a chance of
freezing rain continues this morning along the Arctic Coast. Light
snow fell across Brooks Range passes yesterday, with reports of
heavier snow north of the Brooks Range near Toolik Field Station.
The freezing rain threat will diminish this afternoon as
precipitation turns to rain, but will return overnight as lows
drop back down below freezing. Winds along the coast remain
onshore at 5 to 15 mph.

Coastal Hazard Potential Days 3 and 4...None.

&&

.FIRE WEATHER...Expect very similar conditions today as what was
seen yesterday in terms of winds ,temperatures, and relative
humidities, except cooler and wetter in the western Interior. The
pattern of shortwaves from the east will continue through most of
the week, so showers and afternoon and evening thunderstorms will
continue. On Tuesday, near Red Flag conditions are expected over
the Yukon Flats with dry northeast winds feeding a deep surface
low over the Central Interior. At this time, temperatures and
winds look to meet criteria, and the pattern is certainly
supportive of RHs less than 25% as well. Model guidance continues
to largely indicate RHs being 25% or above, but we did nudge the
forecast to the drier guidance as we suspect that this will
verify. Will continue to monitor as Tuesday approaches.

Thunderstorms today will be isolated to widely scattered over most
of the central and eastern Interior, with the most coverage
expected over the White Mountains and Fortymile Uplands, as well
as from Tanana northeast to the south slopes of the Brooks Range.
Similar conditions are expected Tuesday and Wednesday, though
Wednesday will likely be a much wetter day with numerous showers
producing more in the way of wetting rain.

&&

.HYDROLOGY...The water level in Fort Yukon will continue receding very slowly.
Satellites and ground observations continue to indicate abundant
snow in the Porcupine Mountains. As temperatures warm this week,
snowmelt could lead to continued high water along the Porcupine
and the interrelated sloughs.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Winter Weather Advisory for AKZ808-809.
PK...Gale Warning for PKZ801-802.
     Small Craft Advisory for PKZ803-811-852-857.
     Small Craft Advisory for PKZ804.
     Gale Warning for PKZ805-850-853-854.
     Gale Warning for PKZ806.
     Brisk Wind Advisory for PKZ807-810.
     Brisk Wind Advisory for PKZ808-855.
     Brisk Wind Advisory for PKZ809.
     Small Craft Advisory for PKZ812-858.
     Gale Warning for PKZ816-817-851.
     Heavy Freezing Spray Warning for PKZ817.
     Gale Warning for PKZ856.
&&

$$

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