594
FXAK69 PAFG 212352
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
352 PM AKDT Thu Aug 21 2025

.SYNOPSIS...

An active pattern will bring a series of strong storm systems
across the state. Hazards over the next 7 days will range from
high surf and strong winds along the West Coast, heavy rain across
much of the state, and potential high wind and mixed
precipitation/snow in the Brooks Range.

&&

.KEY WEATHER MESSAGES...
Central and Eastern Interior...

- Multiple storm systems this weekend into next week are expected
  to bring several rounds of rain (heavy at times) and strong
  winds (especially at higher elevations).


West Coast and Western Interior...

- A storm system exiting the region to the northeast will continue
  to bring gusty winds up to 30 mph, scattered rain showers
  (40-50% chance) and high surf along coastal areas the rest of
  the day today.

- A second strong coastal storm is expected on Saturday, bringing
  another round of potentially heavy rain, high surf, and wind
  gusts up to 50 mph.

- An active pattern will continue well into next week, with
  multiple days of heavy rain possible.


North Slope and Brooks Range..

- A strong storm system will bring strong southerly winds, periods of
  rain, and low visibilities today into tomorrow.

- A second strong storm system will impact the region this
  weekend, bringing another round of heavy rain. High winds are of
  increasing concern in the Central and Eastern Brooks Range as
  well.

- An active pattern will continue well into next week, especially
  for portions of Northwest Alaska.

&&

.FORECAST ANALYSIS AND DISCUSSION...

...Today into Tonight...

Currently, an upper-level disturbance is positioned over North-
Central Alaska, moving towards the east-northeast. This
disturbance will continue to bring widespread rain showers (70-90%
chance) across a large swath extending from the West Coast to
Northeast Alaska. A tight gradient in 850 hPa isoheights
immediately downstream of the mid-level vort max will move into
the Brooks Range later this afternoon, bringing strong gusty
winds out of the south up to 50 mph, particularly in the higher
elevations, this afternoon through the overnight hours tonight.

...Tomorrow and Tomorrow Night...

A semi-permanent polar low situated over the Chukchi Sea will
continue to promote troughing over the Bering Strait and Northern
Alaska. With the trough axis to the west and embedded weak
shortwave disturbances traversing the state, there will be
numerous rounds of light rain showers across much of Western and
Northern Alaska during the day on Friday in advance of the next
storm system (which should begin impacting the West Coast Friday
Night into Saturday). Precipitation chances across Western and
Northern Alaska will be on the higher side tomorrow because of
this, ranging from 50-70% with higher probabilities in and near
high terrain. Precipitation chances will be lower across the
Central and Eastern Interior (30-40% chance) where low-level
moisture will struggle to penetrate that far inland, and the
strongest forcing for ascent will remain to the north and west.

...Saturday...

Friday Night into Saturday Morning, a strong mid-level disturbance
is expected to move into Northwest Alaska from the Northern Bering
Sea. At the surface, a low-pressure will move across the Bering
Strait and into the Kotzebue Sound towards the Western Brooks
Range. A tight surface pressure gradient will result in strong
winds across much of Western Alaska gusting 25-40 mph, with gusts
up to 50 mph along the West Coast and at higher elevations. By
late Saturday Morning and into Saturday Afternoon, high winds
appear to be increasingly likely throughout the Brooks Range with
south winds of 35-45 mph, and gusts as high as 70 mph,
particularly at the highest elevations and in north-south
oriented passes (50% chance).


This storm system will also be the first in a series of storm
systems along a plume of moisture originating from the tropical
Northwest Pacific. Rainfall amounts Friday Night through Saturday
Night will range from 0.5" to 1.5" for most of the West Coast and
Western Interior. Locally higher amounts of 2-3 inches will be
possible on southward facing slopes of the Western and Central
Brooks Range. Elsewhere across the North Slope and Central
Interior, while rain chances will still remain high (70-90%),
rainfall rates should be much lower with rainfall amounts through
Saturday closer to half an inch. Further southeast into the
Eastern Interior, there will be enough distance from the stronger
forcing and more ample moisture to the northwest to keep light
rain showers that develop during the day isolated (20-40% chance).
Rainfall amounts here should remain well under 0.25". Saturday
night with temperatures falling into the low and mid 30s,
rain/snow mix will be possible across much of the Brooks Range and
Southern North Slope.

&&

.FIRE WEATHER...

Fire weather concerns will be very low across the state with the
exception for the Upper Tanana Valley. Min RH values through the
rest of the week and into this weekend will dip down into the mid
and low 30s. Light south/southwest winds of 5 to 10 mph for the
end of this week will strengthen with the approach of unsettled
weather from the northwest. By Saturday afternoon, winds will be
out of the southwest at 10-15 mph, potentially gusting up to 25
mph. Winds will weaken by the end of the weekend, and min RH
values will increase into the 40s with the arrival of more low-
level moisture as a slough of storm systems traverse the state to
the northwest. By the beginning of next week, daily isolated
(20-30% chance) rain showers should make it into the Upper Tanana
Valley, also helping to increase low-level moisture. Winds during
this time frame should remain largely out of the south at 5-15
mph.


&&

.HYDROLOGY...

There will be two main rounds of heavy precipitation to discuss
this forecast period. The first is for portions of the Western and
Central Brooks Range Friday through Saturday Night. With the
approach of the next storm system from the Bering Strait,
widespread rainfall amounts of 1 to 1.5 inches are expected from
the West Coast into the Central Brooks Range. The plume of highest
moisture (and heaviest precipitation rates) are expected to set up
from the eastern Kotzebue Sound into the Western Brooks Range.
Here, isolated locations may receive 2 to 3 inches of rain by
Saturday Night. Fortunately, there will be minimal response to
most rivers in the Koyukuk and Kobuk basins with flow currently
below normal. The one river that remains above normal flow is the
Wulik, which may be more sensitive and have a stronger response
to any heavy precipitation. Fortunately, the bulk of QPF will be
well to the east of the Wulik and its headwaters. However, it
bears keeping in mind that should the heaviest precipitation shift
further west than expected, there may be some minor flooding
along the Wulik this weekend and into early next week.

The second round of heavy rain will focus more on the Central
Interior. While there is still substantial model variability
between medium range guidance members and their respective runs,
confidence is increasing in a multi-day stretch beginning Sunday
of heavy rain in this region. Large swaths of the Central Interior
may see 0.75" to 1.0" daily precipitation for 2-3 days in a row.
Furthermore, snow levels will be relatively high for this event;
above 8000 feet. Should this realize, heavy rain may fall on
glaciers in the Central Alaska Range, potentially exacerbating
glacier run-off. The complicating factor to this is medium range
guidance also is trying to resolve a deepening low in the Bering
Sea beginning next week which would act to rotate the plume of
moisture coming in from the Northwest Pacific with a stronger
meridional orientation. As such, will wait and see how subsequent
model runs resolve this potential scenario and see if this signal
holds.


&&

.EXTENDED FORECAST DAYS 4-7...

Sunday and into next week, longwave troughing is expected to
amplify over the Bering Sea and far Northeastern Russia. On the
east side of this quasi-stationary trough, a plume of moisture
will extend from the Northwest Pacific, northeastward into the
West Coast. Multiple embedded disturbances in this longwave
pattern will bring multiple storms systems across the state in the
extended. While timing, location and intensity details are still
very uncertain at this time frame, there is increasing confidence
in one, or multiple storm systems bringing a multi-day period of
heavy rain to Southwest Alaska and the Central Interior stretching
from the end of this weekend to the beginning of next week.



Coastal Hazard Potential Days 3 and 4...None


&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...High Surf Advisory for AKZ822-824-825.
PK...Small Craft Advisory for PKZ803-805-813-859.
     Small Craft Advisory for PKZ804-814-852-860.
&&

$$

Darrah