High Wind in Alaska, August 15 to 16, 2024

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
643 AM AKDT Thu Aug 15 2024

SYNOPSIS...
Back-to-back storms track northeast across the area late this week
then again this weekend. Impacts will be varied across the area
but are generally greatest along the West Coast where gusty
winds, high surf, and heavy rainfall are expected. Repeated
rounds of heavy rainfall should result in swollen rivers,
especially on the Seward Peninsula and across the western Brooks
Range. Across the interior and North Slope, Chinook flow results
in above normal temperatures with highs in the 60s and 70s through
the weekend for lower-elevations across the east. Sunday appears
particularly warm with several sites possibly warming above 80F.

DISCUSSION...

Upper Levels and Analysis...
The 06z analysis indicated a 512 dm Arctic low spinning 300 miles
northeast of Wrangel Island and a 553 dm low spinning over the
Andreanof Islands this morning. The Arctic low lifts northeast
away from Alaska today while the Aleutian low deepens to around
539 dm while tracking north through the Bering Strait tonight.
Another low takes a similar storm track Saturday night into Sunday
at around 530 dm. At the surface, a 985 mb low deepens to 981 mb
near St. Matthew Island today before tracking north across the
Seward Peninsula tonight. This low pressure gradually weakens to
around 988 mb while tracking north near Utqiagvik Friday
afternoon. The second low pressure passes St. Matthew Island
around 987 mb Saturday night before tracking near Utqiagvik around
990 mb Sunday night. Ridging builds across the area at the
surface and aloft early next week.

Model and Forecast Discussion...
Model guidance continues to be in good agreement regarding back-
to-back wet and breezy storms mainly impacting the West Coast,
western Brooks Range, and western interior through this weekend.
The primary model trend is to increase rainfall amounts across the
northwest 2/3 of Northern Alaska and decrease rainfall amounts
across the southeastern 1/3. This model trend spills over into
temps with more persistent above-normal temps across the entire
area, but especially across the southeast where rainfall chances
are decreasing. Ensemble means continue to trend wetter with the
weekend storm indicating increasing potential for back-to-back
heavy rainfall events. Model spread decreases early next week
when chilly ridging builds across the area. Tuesday morning looks
particularly chilly across the interior as 1022+ mb surface
ridging traverses the area bringing potential for patchy frost.

Central and Eastern Interior...
Ridging builds across the Interior this week with dry weather
until an approaching cold front brings rain chances mainly to the
north-central interior late Thursday night through Friday night.
Above-normal temperatures generally prevail throughout the
forecast period, especially across the southeastern portions of
the area. Southerly winds through the AK Range passes are already
increasing and should reach peak intensity late today or tonight
when 50+ mph gusts are likely. Model guidance continues to
indicate the strongest pressure gradient in the vicinity of
Denali implying potential for stronger winds through Windy Pass
than Isabel Pass. Further to the north, gusty winds appear fairly
widespread on Friday but the potential for gusts >35-40 mph
appears to be elevation dependent. Trends toward drier weather on
Friday implies potential for deeper mixing and more widespread
strong winds. In fact, model soundings suggest potential for
stronger winds/gusts this evening due to mostly sunny skies
allowing for mixing up to around 5 kft.

West Coast and Western Interior...
An approaching low pressure results in a strengthening warm air
advection regime that forces a broad area of rain spreading
north through this afternoon. Heavy rainfall of 1-2 inches is
expected for southerly aspects of the Seward Peninsula, Brooks
Range, and other higher elevation locations by Friday morning.
Except for the western Brooks range, lighter rainfall is expected
to accompany increasingly onshore flow on Friday as the surface
low lifts north to near Utqiagvik. The southern portion of this
area still looks to see south to southwest winds gusting to around
35-45 mph. Shortwave ridging quickly lifts north across the West
Coast Friday evening and overnight ahead of the next Bering Sea
low that brings another round of heavy rain and breezy conditions
over the weekend.

North Slope and Brooks Range...
Southerly winds today back easterly tonight as a ridge axis moves
overhead ahead of the approaching low pressure that tracks north
to near Utqiagvik by Friday afternoon. Strong wind gusts >40 mph are
likely for the Brooks Range passes tonight through Friday. East
of the low pressure track winds veer southerly allowing for
continued warmth with temperatures approaching 70F along the
coastline east of Deadhorse. Only light rainfall is expected east
of the low track, but moderate rainfall is possible near the low
track across the western North Slope. The cold front sweeps east
late on Friday into Saturday with more seasonable post-frontal
temperatures until warm air advection ramps up again Saturday
night with the next low pressure system. Weather impacts with the
weekend storm appear very similar to the late week system with
warmer and drier weather east and cooler and wetter weather west.

Extended Forecast Days 4-7...
The back-to-back wet and breezy storms depart early next week with
good model consensus regarding ridging building across the
interior early next week. This chilly surface ridge may instigate
the first frost/freeze of the season Tuesday and/or Wednesday
mornings before warm air advection increases on Wednesday. The
general model consensus continues to show the remnants of Typhoon
Ampil staying well to our southwest or just east of the Kamchatka
Peninsula through the middle of next week.

Coastal Hazard Potential Days 3 and 4...
A pair of coastal storms impact the West Coast with high surf and
potential for minor coastal flooding through the weekend.

FIRE WEATHER...
A warming and drying trend is expected ahead of today's storm
developing over the Bering Sea. Temperatures will rise to around
70F across the central and eastern interior with relative humidity
dropping to around 30%. Winds will be gusty this afternoon and
again Thursday afternoon. After a brief cool down on Friday,
warmer and drier conditions returns to the east this weekend.
Sunday looks particularly warm with high temps around 80F
possible.

HYDROLOGY...
Water levels on the Tanana River remain below minor flood stage,
but above bankfull from Fairbanks to Manley Hot Springs. Water
levels gradually fall through the week, but remain near bankfull.

Along the West Coast, moderate to heavy rainfall develops today and
continues into Friday as a strong coastal low lifts northeast.
Flooding will be possible on the Southern Seward Peninsula,
including the Snake River at Nome. Another round of heavy
rainfall is increasingly likely this weekend leading to continued
flooding concerns.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...High Surf Advisory for AKZ801-815.
PK...Small Craft Advisory for PKZ802-803-805.
     Small Craft Advisory for PKZ804.
     Small Craft Advisory for PKZ806-807-810-816-817-851-854.
     Small Craft Advisory for PKZ808-809-853-855.
     Gale Warning for PKZ811-812-856>858.
     Small Craft Advisory for PKZ813-850-859.
     Small Craft Advisory for PKZ852.
     Small Craft Advisory for PKZ860.
&&