817
FXAK69 PAFG 230038
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
438 PM AKDT Wed May 22 2024


.SYNOPSIS...
The West Coast and Western Interior are wet and cool and will
remain so through the weekend. The Eastern Interior is mainly dry
with near normal temperatures today and Chinook winds decreasing
along the Alaska Range this afternoon, but showers and much
cooler temperatures moving into the Central Interior now will
spread east across the Interior tonight and Thu, with showers and
cool temperatures continuing into the weekend.

The North Slope has near normal temperatures along with coastal
stratus and fog that will continue into the weekend, with the
Eastern North Slope having the possibility of several inches of
snow Fri into Sat.

Aloft...
The long wave pattern consists of a trough over the Bering and
Chukchi Seas, a ridge over the NE Pacific north over eastern
Alaska. A series of short wave troughs will move east across
southern AK from through the weekend, eventually pulling the long
wave east over Mainland AK by the weekend. This will change the
current warm Eastern Interior to cooler and wetter Thu into the
weekend, while the cool and wet West Coast remain so into the
weekend, and the North Slope has little change through Thu then
cools over the weekend.

A strong short wave trough over SW AK will move to lie from the
Bering Strait to the SE Interior on Thu, to the Bering Strait to
Arctic Village to Eagle on Fri, and then weakening over NE Ak on
Sat. This will cause shower in many areas NE of the trough, with
precip falling as snow falling over NE AK Fri into the weekend.

A second strong short wave in the SW Bering will move over the SE
Bering on Thu, over SW AK on Fri, and into the Gulf of AK on Sat.
This will push a vertically stacked surface low east.

A third and stronger short wave will move from the High Arctic to
near Utqiagvik Sat night and then drop south over NW AK on Sun
and over SW AK on Mon. This will bring much cooler temps to the
West Coast Sun into Mon.


Surface...
Strong high pressure north of the Arctic Coast is causing east
winds along the Arctic Coast and keeping stratus and fog in place.
Little will changes through Fri.

A thermal trough that lies from Chicken to Bettles will move
Chicken to Arctic Village by 4pm Thu, and then persist into Fri.
Expect isolated showers long this trough, with isolated
thunderstorms along the ALCAN Border on Thu.

A 1002 mb low over the Yukon Delta will move to near Point Hope as
a 1012 mb low by 4pm Thu, then weaken slowly through Fri. An
occluded front extending from this low to the Seward Pen to Denali
will move move Point Hope to Delta Junction on Thu, then to Point
Hope to Northway on Fri and weaken. This is what is pushing the
showers and cool air east.

A strong low in the southwest Bering Sea will move to the Central
Bering Sea on Thu, and to Kuskokwim Bay on Fri then into the Gulf
of Alaska on Sat. This will bring more rain to Southwest Alaska
Thu night and Fri.

&&

.DISCUSSION...
Aloft at 12Z, models initialize about 10 meters too low with the
500 mb heights of the ridge over Eastern AK but do well on most
features. Models show similar solutions aloft through 4pm Fri,
then the NAM becomes the outlier with a much weaker low aloft than
other models dropping southwest across NW AK Fri night and Sat.
At this time favor a blend of the GFS, ECMWF and Canadian models
for features aloft.

At 850 mb, temperatures range from 6C along the ALCAN border to 0C
along the Arctic Coast and -6C over SW AK. Temperatures will cool
4C over the North Slope and most of the Interior on Thu, with
little change into Fri except further cooling over the North
Slope. Sat will see little change other than continued cooling
over the North Slope and West Coast. All areas see cooling on
Sun.

With precipitation, the NAM is an outlier from other models with
areas of heavy precip over the next several days that appears to
be convective. Since we favor the GFS and ECMWF aloft, with use
those models in a blend for precip as well. Highlights include:
broad area of rain over the West Coast and Western Interior that
will spread east over the Central Interior this afternoon/evening,
and then continue east over the Eastern Interior late tonight into
Fri and over the Eastern North Slope Fri into Sat. Expect
0.10-0.25 in of rain over the West Coast and Western Interior
through Thu. Expect 0.10-0.25 inch of rain over the Eastern
Interior between tonight and Fri, with higher amounts possible
southeast of Fairbanks. Expect 0.20-0.40 inch liquid over the
Eastern North Slope Fri into Sat, with most of this falling and
snow and accumulating several inches of snow from the Dalton
Highway East. Another band of rain will spread over SW AK Thu
night and Fri.

At the surface at 18Z, models verify very well on most features
over AK, except that all models verify 3-5 mb too weak on the low
near Shemya. Models actually have similar solutions through Sat
at the surface so will use a blend of models for surface features
and winds. Highlights are: Winds currently decreasing in the AK
Range this afternoon. Northeast winds 10-20kt over the Arctic
Coast increasing to 15-25 kt on Thu with those winds spreading
south to the Bering Strait and St Lawrence Is on Fri and then
south to the YK Delta on Sat.

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

&&

.FIRE WEATHER...
Today is slightly cooler and more humid than Tue was, and the
chinook winds are decreasing along the AK Range this afternoon.
Generally wet and cool conditions will continue into the weekend.
Expect wetting rain across most of Interior Alaska sometime
between now and Fri.

A weather front over the Western Interior will move Point Hope to
Delta Junction on Thu, then move to Point Hope to Northway on Fri
and weaken.

A thermal trough that lies from Chicken to Bettles will move
Chicken to Arctic Village by 4pm Thu, and then persist into Fri.
Expect isolated showers long this trough, with isolated
thunderstorms along the ALCAN Border on Thu.

&&

.HYDROLOGY...
A flood watch for ice jam flooding remains through Friday on the
Yukon River across the Yukon Delta to the coast. The break up
front and the risk of flooding is expected to get to the Yukon
Delta at Alakanuk, Emmonak, Nunam Iqua and Kotlik sometime between
today and Friday. If an ice jam forms, water could rise rapidly
at any of these locations. The threat of flooding from Mountain
Village upstream is over.

An observer reported on Wednesday that water level has dropped at
Mountain Village and ice has thinned significantly. An observer
at Emmonak reported Wednesday morning that water level had come
up about 3 ft since Tuesday, that ice had shifted, and that ice
remains intact and strong downstream. The observer at Emmonak
indicated that the ice level was still well below the bank
Wednesday morning. With the river ice in the Yukon Delta thicker
than normal this year, it is more likely that ice jams will form
as high water comes down river. Satellite imagery indicates
stronger than normal shorefast ice along the Yukon Delta Coast
which could impede the push of break up ice and lead to increased
risk of flooding in communities near the coast.

The water levels along the Porcupine River at Old Crow rose
dramatically last weekend due to heavy snowmelt and remain high.
This high water is expected to reach Ft Yukon between Thursday and
Friday, with water levels peaking at Ft Yukon over the weekend.
This high water will gradually fill sloughs and swales east of Ft
Yukon late this week and could bring flooding into Ft Yukon this
weekend with high water continuing into next week. A flood watch
is valid for Ft Yukon through next week Wed.

Rivers on the North Slope are beginning to flow with water
flowing over ice with some open water areas. Those area will
continue to see increasing melt this week.

We have no new information on the Buckland River at Buckland.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Flood Watch for AKZ825.
     Flood Watch for AKZ833.
PK...Small Craft Advisory for PKZ811.
     Small Craft Advisory for PKZ812.
     Small Craft Advisory for PKZ851.
     Brisk Wind Advisory for PKZ857.
     Small Craft Advisory for PKZ858.
&&

$$

JB