680
FXAK69 PAFG 182331
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
331 PM AKDT Mon Aug 18 2025

.SYNOPSIS...

A storm system currently situated over northwest Alaska will
continue its progression eastward tonight into tomorrow, bringing
heavy rain and snow to the Brooks Range and North Slope. Rain
showers will fill into much of the Central and Eastern Interior
during the day tomorrow. Wednesday, high pressure and clear skies
will occupy much of the Interior, allowing lows across Central
Alaska to drop near or below freezing. By Wednesday afternoon, the
next storm system will move into Northwest Alaska from the Bering
Strait, bringing gusty winds, high surf, and periods of heavy rain
to the West Coast. This system will bring similar impacts across
Northern Alaska into Thursday, though snowfall should be kept to
the higher elevations.

This upcoming weekend will be the beginning of another potentially
active stretch of weather. Multiple disturbances are expected to
traverse Alaska this weekend into next, with impacts ranging from
heavy rain, wind, snow in higher elevations, and high surf/minor
coastal flooding (this last hazard confined to the West Coast,
particularly the Norton Sound).

&&

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

- A storm system will bring widespread rain (60-80% chance)
  tomorrow and tomorrow night. Rainfall amounts should largely
  remain under 0.25".

- High pressure and clear skies will help temperatures cool into
  the low and mid-30s across much of the Central Interior Tuesday
  Night into Wednesday Morning. Areas of frost will be possible.

- A more unsettled weather pattern takes hold beginning Thursday,
  with daily chances (30-50%) of rain through the weekend and into
  early next week.


West Coast and Western Interior...

- Tonight, a storm system passing the region to the north will
  bring cloud cover, and isolated rain showers (20-30%).

- Wednesday into Thursday, a second storm system will bring
  widespread rain showers (70-80% chance) and gusty winds up to 30
  mph.

- Strong southwesterly winds may result in high surf, and minor
  coastal flooding along the West Coast on Thursday, particularly
  for portions of the Norton Sound.


North Slope and Brooks Range..

- A storm system will bring heavy rain and snow to much of the
  Brooks Range and Southern North Slope tonight into tomorrow.
  Some locations in Northeast Alaska could see 1-3 inches of snow.

- A second storm system will bring another round of heavy rain to
  the Western Brooks Range Wednesday into Thursday, with some
  locations seeing up to an inch of rain.


&&

.FORECAST ANALYSIS AND DISCUSSION...

...Today through Tomorrow Night...

As upper-level ridging continues to break down over the Bering
Sea, an arctic low continues to deepen across the Chukchi Sea,
allowing troughing to deepen across much of Northeast Russia and
Northern Alaska. Embedded in the troughing aloft, a shortwave
disturbance currently situated just west of the Lisburne Peninsula
is expected to amplify and track eastward across Northern Alaska
tonight into tomorrow. The attendant storm system at the surface
will bring widespread precipitation (70-90% chance) across the
region, primarily the Brooks Range and the Southern North Slope.
The heaviest rain looks to fall in the Western Brooks Range, with
rainfall amounts as much as one inch by the end of the day
tomorrow.

Further east across Northeast Alaska, temperatures tonight are
expected to drop into the 20s and lower 30s, especially in the
higher terrain of the Brooks Range. Here, 1-3 inches of snow is
expected, with local terrain enhancements potentially yielding
isolated pockets of 4 inches before this storm system exits the
region tomorrow night.

South of the Brooks Range, the lack of synoptic lift will limit
the extent of heavy precipitation. However, there should still be
sufficient moisture and enough forcing for ascent to result in
widespread rain showers (60-80% chance) across much of the
Interior tomorrow during the day. Rainfall accumulations will be
on the lighter side, likely remaining under 0.25 inches.


...Wednesday...

A post-frontal high pressure coinciding with synoptic scale
subsidence on the upwind side of the first shortwave will help
skies clear across much of Alaska late Tuesday Night into
Wednesday Morning. This coupled with light winds at the surface
will help temperatures drop into the 20s and 30s for nearly the
entire forecast area. As such, many may see the first meaningful
frost of the season Wednesday morning. The one exception will be
portions of the Eastern Interior, where cloud cover may not clear
in time for radiative cooling to yield the same low temperatures
as elsewhere in the state.

By Wednesday Night, another shortwave will approach Northwest
Alaska from the Bering Strait, bringing increasing cloud cover,
windy conditions (gusts up to 30 mph), and rain heading into the
end of the work week.

&&

.FIRE WEATHER...

Fire weather concerns continue to remain low across the forecast
area. However, with 50 to 100 J/kg of MUCAPE in the Upper Tanana
Valley, there will be a slight chance for a lightning strike or
two tomorrow afternoon with min RH values around 50% near the
Canadian border. Elsewhere, cloud cover, frequent chances for
rain, and min RH values above 50% will allow unfavorable fire
conditions to persist this week into the upcoming weekend.

&&

.HYDROLOGY...

There will be two areas of focus for potential heavy rain later
this week into the upcoming weekend.

First will be an area extending from the Southern Lisburne
Peninsula into the Central Brooks Range. Today`s storm system and
the Wednesday/Thursday storm system will each likely produce 0.5"
to 1" of rain in this area. On already saturated soils, a third
system on Saturday will potentially bring another 1.0 to 1.5" of
rain. This will likely result in elevated water levels in small
watersheds in the area. Minor flooding cannot be ruled out.

The second area for potential heavy rainfall will be this weekend
into early next week across the Central and Eastern Interior. An
active pattern featuring west/southwesterly flow with back to
back storm systems may result in rainfall amounts as high as 1-3
inches. While this is still in the extended forecast, there is
enough certainty to keep an eye on this time frame for potential
minor hydrologic impacts.


&&

.EXTENDED FORECAST DAYS 4-7...

The extended forecast period will be defined by an active and
progressive upper-level pattern across Alaska. Broad southwesterly
flow aloft and a series of embedded disturbances in quick
succession will result in multiple storm systems bringing periods
of rain, wind, and high elevation snow this weekend into next
week. As stated in the Hydrology section of the AFD, there will be
the potential for heavy rain and corresponding minor hydrologic
impacts in the Central and Eastern Interior where the more
persistent strong forcing for ascent will reside. Periods of
gusty winds (gusts up to 30 mph) and southwesterly flow will
result in periods of high surf, with a low chance for minor
coastal flooding on Thursday.


.Coastal Hazard Potential Days 3 and 4...

Periods of gusty winds (gusts up to 30 mph) and southwesterly
flow will result in occasional high surf, with a low chance
(10-20%) of minor coastal flooding for portions of the Norton
Sound on Thursday.


&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...None.
PK...Small Craft Advisory for PKZ804.
     Small Craft Advisory for PKZ806>808-855.
     Small Craft Advisory for PKZ812.
     Small Craft Advisory for PKZ813.
     Small Craft Advisory for PKZ852.
     Small Craft Advisory for PKZ854.
     Small Craft Advisory for PKZ856.
     Small Craft Advisory for PKZ858-859.
&&

$$

Darrah