962
FXAK69 PAFG 292224
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
224 PM AKDT Sun Sep 29 2024

.SYNOPSIS...
Ridging builds across interior Alaska through Monday before shifting
north across the Beaufort Sea through the middle of next week. This
pattern brings mostly clear skies and large diurnal temperature
ranges (warm days/chilly nights) through Tuesday. Highs near or
above 50F are expected at lower elevations - especially the Tanana
Valley - through tomorrow and perhaps Tuesday too. Sub-freezing lows
are expected in most locations away from more coastal portions of
the YK Delta and Seward Peninsula.

DISCUSSION...

Analysis and Forecast Discussion... The 20Z surface analysis
indicated a 986mb low over the Canadian Archipelago, a deepening
1003mb low approaching Cold Bay, and 1018+mb ridging in-between
across most of Northern Alaska. A similar pattern is found aloft and
is expected to amplify through tomorrow as a deep low pressure
develops over the Gulf of Alaska. By Monday evening, a sub-960mb
vertically stacked low to our south and a 1028+mb surface ridge over
the Beaufort Sea results in a considerable pressure gradient across
the state. Most of this gradient is south of the Alaska Range, but
seasonably strong northeast winds are expected at Dalton and Elliott
Highway summits along with breezy conditions elsewhere. The primary
near-term weather maker is the ridge building across northern AK
resulting in mostly sunny and warm days then mostly clear and chilly
nights.

Central and Eastern Interior...Much like Saturday, patchy morning
fog lifted to a few stratus decks that are barely moving beneath the
building ridge. Clear blue skies prevail across most of the eastern
interior and North Slope with temps warming into the 40s in most
spots. Despite decreasing day length and solar angle, mostly clear
skies should allow for large diurnal temperature ranges (warm days
and cool nights) near if not greater than 20F. This generally
results in high temps within a few degrees of 50F (above 50F in
sunny valley spots such as Fairbanks) and low temps mainly in the
20s through Monday. As the Gulf of Alaska low moves ashore on
Tuesday, expect high level clouds to increase and shave a few
degrees off high temps. If clouds fail to occur then Tuesday`s temps
may be very similar to Monday. Winds will be mostly light, though
northeast winds are likely to gust to around 30-40 mph for Dalton
and Elliott Highway summits Monday afternoon.

West Coast and Western Interior...Humid southeast flow across the YK
Delta is resulting in some sprinkles/drizzle, but model soundings
show a shortwave tonight and tomorrow night that should bring brief
rounds of light rainfall. Expect mostly sunny skies in the Interior
north of Galena through Monday and perhaps Tuesday too. Generally
light southeast winds back northeasterly Monday night before veering
southeasterly and increasing Wednesday night as a seasonably strong
storm moves across the Bering Sea. Highs will be in the 40s with
lows in the 30s. A few spots may warm to near or perhaps a few
degrees above 50F Sunday and/or Monday.

North Slope and Brooks Range...The CIRA Snow Cloud Discriminator RGB
satellite pass at 1926Z showed two ribbons of new snow cover on
Point Utqiagvik. Overnight satellite imagery showed cloud streets
streaming across the area and model soundings were marginally
supportive of sea-effect snowfall so that`s probably what happened.
Model soundings imply a similar pattern in the easterly flow south
of the ridge on Tuesday into Wednesday that may bring some light
snow showers to locations between Utqiagvik and Deadhorse. However,
light winds and ridging overhead imply a chilly night is in store,
but increasing southeast flow may keep mixing and temperatures
elevated and perhaps allowing for a rapid warm up into the 40s
across the western North Slope on Monday.

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

Extended Forecast For Days 4 Through 7...The extended forecast
period begins Wednesday night starts with dry and calm conditions
across the mainland and a weakening surface trough approaching the
Seward Peninsula. Farther to the southwest, a seasonably strong low
pressure crosses the Kamchatka Peninsula and deepens rapidly across
the far western Bering Sea. Model spread in terms of storm intensity
and storm track remains large as this system crosses the Bering Sea,
but an occluding sub-970mb low near or perhaps just northwest of St.
Matthew Island (roughly 61N, 176W) around 10 PM Thursday appears
most likely at this time. Subjective averaging of the stronger
ensemble members implies a minimum pressure between 950-960 mb, but
individual ensemble members range from sub-940mb to above 980 mb.
The strongest winds and largest waves are expected south of the low
track implying greatest impacts across the Southern Bering Sea, but
the low track and intensity should be monitored closely. Vessels
planning to transit the Bering Sea next Thursday/Friday should
monitor forecast updates and consider altering plans. If a stronger
and farther north storm occurs then coastal flooding will also be
possible. The Interior and North Slope remains dry with temps
averaging above-normal quiet weather through the extended period.

HYDROLOGY...No concerns.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...None.
PK...Small Craft Advisory for PKZ815-861.
&&

$$