Area Forecast Discussion
Issued by NWS Fairbanks, AK

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000
FXAK69 PAFG 091449
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
649 AM AKDT Sun May 9 2021

.SYNOPSIS...
Stratus and fog will remain over the North Slope for the next
several days along with cool but near normal temperatures and east
winds 15 to 25 mph. The West Coast and Western Interior over the
next several days will be near or warmer than normal with
isolated to scattered showers with rain more likely today and
Monday over the Yukon Delta and St Lawrence Island, and dense fog
near the Bering Strait this morning. The Interior will remain
warmer than normal for the next several days then cool by mid-
week, with a few showers today, then isolated to scattered showers
on Mon, and increasing chances of showers by mid-week. There will
be a slight chance of thunderstorms in the Fortymile area on Mon
and Tue. South winds of 15 mph with gusts to 25 mph will continue
through Alaska Range Passes through Tue.

Aloft...
The long wave pattern consists of a ridge over Northwest Canada
and Northern Alaska, with a trough over the Bering and Gulf of
Alaska. a series of weak short wave trough will make their way
north over Alaska through mid-week bringing increasing chance of
showers. In the second half of the week, several strong short
waves will move north over Alaska causing the ridge to weaken
further and bring in cooler and more showery conditions.

A weak short wave that lies from the YK Delta to Kodiak, with an
accompanying occluded front underneath it, will move to St
Lawrence Is to Denali to Northway by 4pm Sun, then to the Bering
St to Fairbanks to Northway by 4am Mon, and to Wainwright to
Northway by 4pm Mon, to Deadhorse to Northway by 4am Tue, then
along the ALCAN Border by 4pm Tue. This trough will push
increasing moisture and instability north with the trough.
Widespread showers with this features along the West Coast
decrease to isolated showers over the Interior.

A second trough, and occluded front, in the Western Gulf of
Alaska will move north to the YK Delta to Gulf of AK on Mon, and
to Norton Sound to Northway by Tue. This will bring additional
moisture and increasing chances of showers on Tue.

Surface...
High pressure north of the Arctic Coast of Alaska will persist
through Wed.

A weather front over the Yukon Delta will move to the Bering
Strait by 4am Mon and to Point Hope by 4pm Mon. A second weather
front in Bristol Bay will move to the Yukon Delta by 4am Mon, and
over Norton Sound Mon night and Tue.

A thermal low pressure trough stretching from Tanana to Chicken
will persist into Tue. The thermal trough will cause south winds
of 15 mph with gusts to 25 mph to continue through Alaska Range
Passes through Tue.

A weather front over the Yukon Delta to South Central Alaska will
move to St Lawrence Is to Denali by 4pm Sun, to the Bering Strait
to Tanana by 4am Mon, and to Point Hope to Tanana by 4pm Mon.
East of Tanana the front will merge with the thermal trough.
Widespread rain and snow showers with this front along the West
Coast decrease to isolated showers over the Interior. Expect
isolated thunderstorms in the Fortymile area with this on Mon and
Tue PM

A second occluded front stretching from Bristol Bay into the Western
Gulf of Alaska will move north to the YK Delta to Gulf of AK on
Mon, and to Norton Sound to Northway by Tue. This will bring
additonal moisture and increasing chances of showers on Tue.

Temperatures will remain above normal the next several days, then
cool to near normal by mid-week. Expect a few showers along the
thermal trough today, then isolated to scattered showers on Mon,
and increasing chances of showers by mid-week. There will be a
slight chance of thunderstorms in the Fortymile area on Mon and
Tue.

Expect Min RH 15-30% between the Alaska Range and the Tanana River today,
with RH 25-40% along and north of the Tanana Yukon Uplands.
Expect RH to increase about 5% each day from Mon through Wed.

&&

.DISCUSSION...
At 00Z, models initialize well aloft. Models show similar
solutions aloft through Tue. 850 MB temps remain above normal
today and Mon, then trend cooler to normal by mid-week.

Models differ some in areas of precip coverage, but all show the
same general trend of scattered to likely precip in zones 213
214, with isolated to scattered showers in the remainder of the
West coast and Western Interior, while the Eastern Interior has
isolated precip today and then with precip coverage trending
upwards through the week. Will use a blend of model precip for
coverage, and show the trends previously mentioned.

At the surface at 06Z, models all verify a few mb too weak with
the weak ridge over the Copper River Basin, and 6-8 mb too high on
the low pressured center south of Cold Bay. To account for these
pressure differences, expect south winds 3-5 kt stronger than
models indicate through AK Range Passes today into Mon, and expect
winds 3-5 kt stronger over the SW Interior and West Coast south
of the Bering Strait tonight and Mon.

Bottom line for models is that we will use a blend of models for
temps, precip, clouds and winds, but adjust winds up 3-5 kt
through AK Range Passes today through Mon and long the West Coast
tonight and Mon, and will adjust the pops to show increasing trend
over the Interior today through Tue, while the West Coast has
scattered to isolated showers with showers likely in zones 213 and
214 today and Mon.


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

&&

.FIRE WEATHER...
Temperatures will remain above normal the next several days, then cool
to near normal by mid-week. Expect a few showers along the thermal trough
over the Interior today, then isolated to scattered showers on
Mon, and increasing chances of showers by mid-week. There will be
a slight chance of thunderstorms in the Fortymile area on Mon and
Tue.

Expect Min RH 15-30% between the Alaska Range and the Tanana River today,
with RH 25-40% along and north of the Tanana Yukon Uplands.
Expect RH to increase about 5% each day from Mon through Wed.


&&

.HYDROLOGY...
There is a flood watch for the Yukon River at Eagle that is in
effect through noon Monday. Ice moved at Eagle but is now jammed
in place, with the latest report being that the water has risen a
foot through Saturday morning. The break up front with higher
water remains upstream of Eagle, but should move through Eagle in
the next day or two, causing the ice to either move or jam
further at Eagle. The Yukon near Eagle will continue to be
monitored closely.

The rest of the Yukon River and rivers north of the Yukon remain
frozen, but are starting to have ice lift and shift in a few
places. Melting will increase next week along and north of the
Yukon River as temperatures remain near or above normal.

&&

.PREV DISCUSSION... /issued 302 PM AKDT Sat May 8 2021/

SYNOPSIS...
A beautiful weekend is in store for the Interior as ridging aloft
will keep most areas free from precipitation. Quiet conditions
continue for the West Coast through this evening, while the North
Slope will see continued low stratus and fog despite snow tapering
off along the eastern Beaufort Sea Coast this afternoon.

DISCUSSION...
Aloft, ridging continues to build in from Canada over northern
Alaska this afternoon. The building ridge will work to keep
conditions dry in the Interior until tomorrow. A closed upper
level low over the Aleutians will remain generally in the same
position going into early next week. This feature will send a
shortwave to the north over the Alaska Range late Sunday and
through Monday and continue to drift north to the Brooks Range by
Monday night. This shortwave will weaken the ridge, allowing for
isolated thunderstorm chances for portions of the Interior on
Monday. There are some model differences on the intensity of this
shortwave, which would directly impact the areas that could
potentially see thunderstorms, so this will be a situation to
monitor. Beyond Monday, models are indicating a strong shortwave
moving north out of the Gulf of Alaska that would break down the
ridge even more, but details of this development remain unclear.

At the surface, a weak thermal trough is located over the Tanana
Valley this afternoon, with low pressure in Kotzebue Sound, and
high pressure north of the Arctic Coast. A decaying weather front
associated with the snow and blowing snow issues on the eastern
Arctic Coast will continue to dissipated tonight, with improving
conditions in that region. A weather front near Bristol Bay
associated with a surface low in the southern Bering Sea will move
north and bring the potential for precipitation for areas like
the Yukon Delta, St. Lawrence Island, Norton Sound, and the
Seward Peninsula beginning tonight and lasting into Sunday night.
A secondary weather front may bring a second round of
precipitation to the Yukon Delta on Monday. In the Interior,
another thermal trough will develop on Monday, increasing chances
for thunderstorm activity during the afternoon hours.

Central and Eastern Interior...
Seasonably normal temperatures expected for the area for the rest
of the weekend, with most areas remaining dry. With the
development of the thermal trough, southerly gap winds will
persist for most of the weekend, with 30-40 mph gusts. Portions
of the Fortymile Country and White Mountains will be the focal
point for isolated to scattered showers tomorrow. The
aforementioned shortwave moving north over the Alaska Range and
into the Interior on Monday will increase chances for isolated
thunderstorms for the Eastern Interior on Monday.

North Slope and Brooks Range...
A dissipating weather front will result in light snow ending and
decreasing east winds along the central and eastern Beaufort Sea
Coast this evening. However, low stratus and fog will remain for
most areas along the Arctic Coast through the rest of the weekend.
Temperatures will remain at or slightly below normal through the
weekend.

West Coast and Western Interior...
Quiet conditions continue for the West Coast and Western Interior
today. Increasing clouds and chances for precipitation will
develop tonight as a weather front advances north and west from
the southern Bering Sea for portions of the West Coast from the
Bering Strait south. Temperatures remaining above normal going
into next week.

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

FIRE WEATHER...
A thermal trough set up north of the Alaska Range is resulting in
near Red Flag conditions with RH`s in the 20s and 30s with
southerly gap winds gusting 30-40 mph this afternoon through
Isabel Pass from Donnelly Dome to Black Rapids. These conditions
will improve slightly going into next week. A thermal trough will
redevelop over the Tanana Valley on Monday, increasing the
potential for isolated thunderstorms for the Eastern Interior.

HYDROLOGY...
There is a flood watch for the Yukon River at Eagle that is in
effect through noon Monday. Ice moved at Eagle but is now jammed
in place, with the latest report being that the water has risen a
foot through Saturday morning. The break up front with higher
water near Dawson should move through Eagle in the next day or
two, causing the ice to either move or jam further at Eagle. The
Yukon near Eagle will continue to be monitored closely.

The rest of the Yukon River and rivers north of the Yukon remain
frozen, but are starting to have ice lift and shift in a few
places. Melting will increase next week along and north of the
Yukon River as temperatures remain near or above normal.


&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Flood Watch for AKZ224.

Small Craft Advisory for PKZ210.

Brisk Wind Advisory for PKZ230.
&&

$$

JB MAY 21


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