839
FXAK69 PAFG 172143
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
143 PM AKDT Tue Sep 17 2024

.SYNOPSIS...

A strong low pressure system over the Bering Sea is continuing to
progress eastward and will eventually move into the southwestern
portion of Alaska throughout the afternoon and this will help to
increase shower activity by later in the evening over the Yukon
Valley and eventually into the Interior. Cooler temperatures are
expected by late week over the Mainland, as arctic air moves
southward.

.DISCUSSION...

Upper Levels and Analysis...

A strong area of low pressure that has undergone bomb
cyclogenesis, with the latest heights analyzed at around 966 mb
near the Pribilof Islands, will continue to fill as it propagates
eastward and over the southwestern portion of the state.
Meanwhile, weak troughing to the north of the Mainland has kept
some instability in place. With this, rain showers wrapping
around the back-end of the low will be moving over the East
Interior and increasing through the evening and into tomorrow.

Forecast and Model Discussion...

Latest numerical model data suggest that the trajectory of the
low has trended slightly northward, with a front which will impact
the YK Delta. The EC has a slightly quicker propagation than the
GFS, Canadian, and NAM models. The other models are relatively
more consistent with the timing. This alludes to a slight shift in
the extent of the gale force winds to the north although not as
aggressive with the EC with a slightly quicker progression.
Between the blend of the models and relying mostly on the NAM,
which has been the most consistent, shows will continue to move
more into the Interior by Wednesday through Thursday. A more
pronounced arctic trough will begin to move in by later in the
week and help to bring in cooler air as it sets up over the
Mainland.

Central and Eastern Interior...

Showers will continue to taper off going into the evening hours.
South winds will be increasing, with sustained withs of 45 to 50
mph tonight as the strong low pressure move into the gulf. Showers
will be increasing again by Wednesday and then become more
steady by Thursday, especially over the Alaska Range. These
showers will begin to diminish Thursday night with drier
conditions returning on Friday.

West Coast and Western Interior...

As the strong low pressure moves in the Bristol Bay by later this
evening, rainfall and winds will continue to increase in the YK
Delta and Norton Sound. Gale force winds are expected to impact
the region from Yukon Delta to the Saint Lawrence Island by later
this evening. The low will continue to track into the gulf and all
for the winds to weaken below gale force, with some intermittent
showers still possible going into Friday. There could also be some
snow showers down to around 1000 ft elevation by Thursday night.

North Slope and Brooks Range...

On and off rain showers with patchy fog will continue to be
possible for most of the North Slope with weak troughing still in
place. Snow levels could drop below 1000 ft by Thursday night for
the Brooks range Arctic Plain with colder air beginning to slip
southward towards the end of the week.

Extended Forecast Days 4-7...

There will be drier conditions and overall cooler temperatures
expected by later in the week with the Arctic troughing that is
expected to be moving over the Mainland. That being said, there
will still be some snow showers continuing over the higher
elevations, especially over the Eastern Interior as temperatures
continue to cool. The cooling trend will give way to overall
temperatures being slightly cooler than the seasonal average for
most locations by this upcoming weekend.

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

.HYDROLOGY...
More rainfall is expected for Tuesday and Wednesday with another
0.5 to 0.75 inches over the YK Delta and Lower Yukon Valley/MIddle
Kusko Valley. Smaller stream rises are likely, but will not be
significant. Elsewhere, no concerns as rivers are running low due
to fairly low snow levels.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...None.
PK...Small Craft Advisory for PKZ802-805-816-817-851-853-854.
     Small Craft Advisory for PKZ803-804-852.
     Small Craft Advisory for PKZ806-807.
     Gale Warning for PKZ850.
     Small Craft Advisory for PKZ856.
&&

$$