Area Forecast Discussion
Issued by NWS Fairbanks, AK

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000
FXAK69 PAFG 122159
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
159 PM AKDT Wed May 12 2021

SYNOPSIS...Scattered rain showers and isolated thunderstorms south
and east of Salcha, with some isolated thunderstorms and rain
showers south and east of the Yukon River this evening. Some
clearing in the Interior Thursday as high pressure builds into the
area from the Northwest. Isolated Thunderstorms and rainshowers
mainly south of Fairbanks Thursday as the thermal trough moves to
the north slopes of the Alaska Range. The West Coast looks to be
mainly dry, though a few showers may pop up in the Middle Yukon
Valley, with generally light northeast to east winds. The Arctic
spring continues with low clouds, fog, flurries, and breezy with
blowing snow.

.DISCUSSION...

Models...Short term the 12/12Z Solutions are in good agreement,
but as they move into the extended periods that changes pretty
rapidly, so will need to lean on the ensemble means for the
extended periods. Surface solutions are in good agreement, and
initialized well at 12/15Z against the surface analysis.
Convective numbers are bit little better today with some areas
southeast and southwest of Fairbanks with Lifted Index from +1 to
-1, and non zero CAPE values which is usually a recipe for some
isolated thunderstorm activity, though to the west the ridging may
be enough to cap any activity. Convective numbers for Thursday
and Friday look better, especially south and east of Chicken. With
the thermal trough moving to the north slopes of the Alaska
Range, Going with a blend of the high resolution models for early
in the forecast periods to better target the location of
thunderstorms and rain showers, then transition to a blend of the
NAM and GFS for the remainder of the short term. Not a lot of
changes expected in the winds and temperatures, so will make some
targeted adjustments to warm some of the Interior locations a
couple degrees, and increase winds in a couple coastal locations.

Aloft...At 500 hpa...Ridging over the Yukon Territory extends
west over Chicken to a 553 dam high over Galena. A 550 dam high
has developed over the Eastern Arctic 300 nm north of Prudhoe Bay.
Troughing associated with a low in the Canadian Archipelago is
hanging on over the Eastern Arctic Coast, while to the south a 545
dam low has moved over Kodiak Island, and west of that a 527 dam
low has moved over Shemya. A 530 dam low over Chukotka continues
to ride up the western flank of the ridge and will move into the
Siberian Arctic Thursday. By Thursday afternoon ridging will
persist over the southern Interior extending west to a 553 dam
high over Buckland, while a 546 dam low will develop over the
Eastern Arctic Coast. The low to the south will be over the
Northern Gulf at 545 dam, and the low to the west will move over
Adak at 521 dam. Friday will see a slight change as the low to the
south will move off over the southern Yukon Territory, the high
to the west will move over the Bering Strait at 548 dam, the low
over the Aleutians will move to 100 nm north of Atka, and the low
over the Eastern Arctic coast will slide west over Nuiqsut at 540
dam as a 550 dam high develops over the Central Beaufort Sea. At
850 hpa...Not much change through the weekend as a band of
temperatures between 0C and +4C lies between the ranges.
Temperatures north of the Brooks Range will be in the 0C to -5C
range through Friday, then cool a few degrees as a low aloft pulls
some cooler air south over the northwest coast.

Surface...High pressure associated with a 1038 mb high 200 nm
north of Demarcation Point is pushing southwest over the Upper
Yukon Flats, Eastern Brooks Range, and across the Arctic to a 1022
mb high over Shishmaref, and southwest over St Lawrence Island.
A trough of low pressure lies from the southern Yukon Territory
across the Middle Tanana Valley to the Middle Yukon Valley, then
southwest to Bristol Bay with a 1016 mb low near Dawson YT, a
1017 mb low near Salcha, and a 1018 mb low near Galena. The
thermal trough is north of Fairbanks, but will be sliding south to
the north slopes of the Alaska Range tonight. In the Bering Sea a
992 mb low has moved near Shemya with low pressure extending east
along 50N, then northeast to a 1015 mb low moving into the
southern Gulf of Alaska. Friday will not see much change as high
pressure holds across the Arctic as the high moves to Banks Island
at 1039 mb. The low pressure over the Interior will be in the same
general area with the thermal trough near the Alaska Range. The
low in the Bering Sea will be a 100 nm north of Adak with a front
extending east over the Alaska Peninsula. The low in the Gulf of
Alaska will be 150 nm south of Cordova at 1014 mb. A bubble high
will develop over Southcentral with a 1022 mb center in Prince
William Sound.

Arctic Coast and Brooks Range...Stratus, fog, flurries, blowing
snow, spring in the Arctic. Northeast to east winds along and
near the coast at 15 to 25 mph for most locations will slowly
diminish overnight. Inland variable winds to 10 mph. Temperatures
will remain cool along the coast, but will be warming to near
climatological normals for May with highs in the mid to upper 20s,
and lows in the teens to lower 20s.

West Coast and Western Interior...Some isolated thunderstorms in
the Upper Kuskokwim Basin, with isolated rain showers from the
Seward Peninsula this evening. Isolated rain showers again
Thursday south of the Seward Peninsula. Winds along the coast
generally offshore to 15 mph, while inland winds will be light and
variable. High temperatures in the upper 30s to mid 50s, while
lows will be in the 30s to lower 40s for most areas. Warmest
temperature inland from Galena south.

Central and Eastern Interior...Isolated Thunderstorms and rain
showers south of the Yukon River this evening. Isolated showers
south of the Yukon River again Thursday, with isolated
thunderstorms southeast of Fairbanks. Winds variable to 10 mph.
Temperatures warming through Friday.

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

Extended forecast for days 4 to 7...A system in the Arctic will
bring snow showers to the area for most of the extended period
with some possible clearing late Tuesday. A series of lows moving
into the Gulf of Alaska will send fronts into the Interior with
scattered rain showers Sunday south of the Yukon River. The
remainder of the extended period will see isolated to scattered
afternoon rain showers and isolated thunderstorms. Cooler
temperatures Sunday and Monday across the area, then warming. The
West Coast will remain quiet with some isolated showers from the
Seward Peninsula south.

&&

.Fire Weather...Generally quiet with some very isolated
thunderstorms possible southwest and southeast of Fairbanks this
evening, and Thursday afternoon. Scattered thunderstorms possible
Friday in the Upper Tanana Valley south of Chicken with some
isolated thunderstorms south of Fairbanks to the Alaska Range.
Thermal trough is moving south of Fairbanks today. Relative
Humidity values in the 30s and 40s today falling into the upper
20s to mid 30s Thursday and Friday. Temperatures will be warming
with highs in the 50s and 60s Thursday and Friday.

&&

.Hydrology...Breakup has slowed a bit, but can pick up at
anytime, so our Riverwatch team is out flying the rivers and
checking on the Breakup Fronts as they move downstream. 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 Breakup Front on the
Koyukuk River is downstream of Bettles and may move into the
Allakaket area by later this evening or Thursday unless a jam
forms. 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 PKZ230-PKZ235-PKZ240-PKZ245.

&&

$$

SDB MAY 21


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