Areal Flood Warning 1, NWS Fairbanks, AK

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
219 AM AKDT Thu May 13 2021

.SYNOPSIS...
Normal spring weather continues as we enter into the time of year
when weather is largely dictated by diurnal patterns, including
threats for showers and isolated afternoon thunderstorms. Temps
remain at climatological normals albeit a bit cooler up along the
North Slope. This pattern continues into the weekend.

&&

.DISCUSSION...

Upper Levels and Analysis...
There is an upper low over the northeast part of the Mainland
with a weak ridge centered over the Nulato Hills. Farther south,
very typical for this time of year is a low in the Gulf of Alaska.
Weak ridging extends south into the Alaska Range. Showers and
isolated thunderstorms this afternoon formed along the edge of the
ridge with the upper trough, aided some by diurnal forcing along
higher terrain before drifting downstream. At the surface, a
strong 1040 mb high persists near Banks Island with general low
pressure over the Bering and Gulf of Alaska.

Central and Eastern Interior...
Pretty normal spring weather the next few days with temps
generally in the low 60s and mostly light winds, although a little
breezier over the higher terrain. Afternoon diurnal showers and
isolated thunderstorms look to be mainly relegated to the
Fortymile Uplands and Alaska Range, although there is a slight
chance up to the Tanana Valley and foothills of the White
Mountains.

West Coast and Western Interior...
Light pressure gradients gradually pick up beginning tonight
and continuing through Saturday with increasing north to northeast
winds. Winds will become rather breezy along the West Coast and
Saint Lawrence by Sat with gusts approaching gale force.
Elsewhere, the pattern of afternoon showers and isolated
thunderstorms over the Interior continues over the next two days
as a weak ridge remains in place. There is a chance for some
isolated showers, however, as far west as the Yukon Delta given
the weak easterly flow aloft today, with isolated thunderstorm
chances as far west as the Nulato Hills. Otherwise, much of the
shower activity will be focused over the Yukon Valley the next few
days.

North Slope and Brooks Range...
A combination of fog, stratus, and blowing snow will continue over
the Arctic Coast over the 12-24 hours (mainly the eastern Arctic)
before high pressure settles in and temps gradually warm along
with decreasing easterly winds. This will likely result in more
stratus and fog. Expect some isolated snow showers/flurries at
times into the weekend as an upper low retrogrades west over the
Brooks Range and North Slope.

Extended Forecast Days 4-7...
Beginning the extended period forecast on Sunday, there will be a
large upper low level low center over the northern half of the
Mainland with a weak ridge over the southern Interior. This will
allow for a redeveloping thermal trough north of the AK Range and
increased threats for thunderstorms and accumulating rainfall over
much of the Interior. Models diverge on the placement of the upper
level trough, but the overall pattern is consistent in the global
models. This pattern will likely remain near climatological norms
for temps as we head into late spring.

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

&&

.FIRE WEATHER...
Afternoon showers and isolated thunderstorms will favor the
Western Interior and the Tanana Valley to the AK Range/Fortymile
Uplands today. Activity looks less impressive than yesterday with
lower coverage and a more suppressed thermal trough. Showers and
isolated thunderstorms will continue to be minor threats heading
into the weekend with avg temps and winds on the lighter side. No
major fire weather concerns are anticipated.

&&

.HYDROLOGY...
A flood watch remains in place through this morning along the
Yukon River for Circle (Thu).

The ice jam above Circle remains in place and is backing water up
into low lying areas well upstream. When the ice jam breaks ice
conditions are such that it may just pass right by Circle with
just some high water as the ice at Circle has mostly cleared.
Further downstream on the Yukon River there is still plenty of ice
remaining in place, and if the water rises it could pick up some
of the stranded ice along the banks and take it downstream. Ice
continues to rot in place, but ice in the Rampart Canyon is still
solidly in place, so breakup may slow as it moves into that area
later this week and early next week.

The latest Riverwatch Aircraft recon shows breakup on the Koyukuk
River is continuing nicely with occasional ice floes to Huslia.
From there to Hughes, there were large ice floes moving slower
through the curves in the river. From Hughes to Allakaket the
river was open with ice on bars and edges of the channel. River
levels were low with numerous sand bars visible. Most of the ice
is candling as it rots in place and breaking up once it starts
moving downstream, so only a limited amount of large chunks of ice
are available to get jammed up.

Conditions can change rapidly so go to www.weather.gov/fairbanks
or www.weather.gov/aprfc for the latest information.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Flood Watch for AKZ220.

Brisk Wind Advisory for PKZ240.

Gale Warning for PKZ245.

Small Craft Advisory for PKZ210.

&&

AHSENMACHER MAY 21