029
FXAK69 PAFG 061203
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
403 AM AKDT Mon May 6 2024

.SYNOPSIS...
Shower activity continues through the next several days across
northern Alaska as a series of disturbances move across the
region. South of the Brooks Range a mix of rain and snow can be
expected, while north of the Brooks Range precip will take the
form of snow. Strong pressure gradient persists from the northwest
Arctic Coast southwest to St Lawrence Island supporting gusty
winds today. A Flood Watch remains in effect for the Yukon River
at Circle.

&&

.DISCUSSION...
Synoptic Analysis and Forecast...
Aloft, at 500 mb, a longwave trough extends from the far
northwestern Canadian Archipelago across mainland Alaska and into
the Gulf of Alaska. At the base of the trough a closed upper low
in the central Gulf of Alaska weakens as it lifts north across the
Gulf of Alaska and moves onshore near Yakutat Tuesday morning as
an open wave. As this low and subsequent wave lifts north it
pushes a ridge axis north across the Yukon and Northwest
Territories, as well as the Beaufort Sea. The shortwave continues
north across the eastern Interior Tuesday into Wednesday morning
and then north across the eastern Brooks Range and to the Arctic
Coast by Thursday morning. Further west, another closed upper low
over the Seward Peninsula this morning will track southwest
through the Bering Strait Monday to be near St Lawrence Island
Tuesday morning and the Pribilofs Wednesday morning. North of this
low a weaker remnant upper low will track west and south across
the Chukchi Sea through Tuesday.

At the surface, a 1026 mb high centered 300 NM north of Utqiagvik
moves northeast to be 400 NM north of Kaktovik by Tuesday morning
to 150 NM north of Banks Island by Tuesday afternoon. A weak area
of low pressure over Mackenzie Bay this afternoon tracks westward
along the Beaufort Sea coast with a trough of low pressure
developing from this low near to a 1002 mb low in the Northwest
Territories. By Wednesday afternoon, the trough lifts northwest
off the coast extending from a 1000 mb low over the northern
Northwest Territories to a 1006 mb low 25 NM north of Point
Thompson. A 990 mb low 50 NM southeast of Mayo this afternoon
weakens to 998 mb as it moves to 50 NM south of Eagle by Tuesday
morning to near Arctic Village Wednesday morning. A weak trough
develops south of the Gulf of Anadyr this afternoon and moves
southeast across the Bering Sea through Tuesday with a 1008 mb low
developing near the Pribilofs Tuesday afternoon and moving south
of Nikolski by Wednesday afternoon.

Models...
The 06/00Z models initialized well against the 00Z RAOBS and are
in good agreement with the overall synoptic pattern. Differences
in the details emerge by this afternoon with the upper level low
and energy from the Chukchi Sea to the Seward Peninsula. Models
have struggled with this feature over the last several days as
well. They all bring the low south of the Bering Strait, but exact
placement and strength have varied from model to model and run to
run. Another area that models struggled with aloft is resolving a
shortwave trough that pushes north across the eastern Interior,
the Yukon, and the Northwest Territories and the resulting upper
level low that develops Wednesday into Thursday. There is a wide
spread in solutions and placement of the low, varying from the NAM
over the Eastern Interior to the ECMWF over the western Northwest
Territories to the Canadian which is even further east. This also
translates down to the surface lows. Given the model uncertainty
and run to run inconsistency, opted to lean towards a consensus
blend for winds along the Beaufort Sea coast for the latter half
of the forecast period.

North Slope and Brooks Range...
Gusty northwest winds of 25 to 35 mph persist west of Point Lay
today, elsewhere along the coast northeast winds of 15 to 25 mph
are expected. Winds diminish tonight and are expected to remain
below 15 mph on Tuesday. Developing trough over the eastern
Beaufort on Wednesday shifts winds to the west over the Beaufort
Sea coast and increases them to 15 to 20 mph. Snow chances persist
through the next several days with overall light accumulations
through Tuesday. Higher snow amounts expected Wednesday into
Thursday for the eastern Brooks Range where 1 to 4 inches of snow
are expected. Temperatures trend upwards, with most locations in
the 20s Tuesday and Wednesday.

West Coast and Western Interior...
Strong pressure gradient persists this morning from Point Hope
southwest through the Bering Strait to St Lawrence Island today,
supporting northwest winds of 25 to 35 mph. Gradient weakens
today and tonight. Troughing aloft and energy moving through the
trough will support isolated to scattered rain and snow showers
through the week. Today will be the coolest day of the week as
temperatures trend upwards beginning Tuesday.

Central and Eastern Interior...
Shower chances increase today as an upper level disturbance moves
northwest out of the Yukon. Snow showers possible this morning
across much of the Interior, becoming a mix of rain-snow and rain
showers by this afternoon. Across the south slopes of the Brooks
Range and Dalton Highway summits, precip will likely stay snow
today. Another round of precip is expected Tuesday as a shortwave
moves north across the Eastern Interior bringing rain, snow, and a
rain- snow mix, with the best precip chances across the Upper
Tanana Valley, Fortymile Country, and southeastern Brooks Range.
Snow accumulations generally less than an inch with up to two
inches possible in the White Mountains, south slopes of the Brooks
Range, southern Denali Borough, and south of Trims Camp. Weak
southerly gap flow develops in the Alaska Range passes this
afternoon, continuing through the week and increasing Wednesday
night and Thursday, especially over the eastern Alaska Range,
where a Wind Advisory may be needed Thursday. Cooler temperatures
expected today with temperatures warming once again Tuesday.

Extended Forecast Days 4-7...Guidance continues to indicated
persistent broad upper level troughing over much of mainland
Alaska, Bering Sea, and the Gulf of Alaska, with periodic upper
ridging in Canada nudging into the Eastern Interior. This set up
supports scattered shower activity across northern Alaska and
energy moves through the trough.

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

&&

.FIRE WEATHER...
A series of upper level disturbances will lift northwest across
the Interior through mid week supporting isolated to scattered
showers each day. Temperatures trend downwards today before
warming trend ensues Tuesday. Minimum relative humidity values
largely remain above 25 percent through Tuesday, except for a few
pockets of 20 to 25 percent from Tok to Eagle this afternoon.
Slightly lower minimum relative humidity values expected Wednesday
afternoon from the Middle Tanana Valley east to the Alcan border.
Winds generally less than 15 mph. Weak southerly gap flow
develops in the Alaska Range passes Monday afternoon continuing
through the week and increasing Wednesday night and Thursday,
especially over the eastern Alaska Range.

&&

.HYDROLOGY...
As of mid-day Sunday, not much change has been reported and the
Yukon River breakup front is roughly 30 miles upstream of Circle,
near Coal Creek. There is a 20 mile run of dense ice above the
breakup front. Residents of Circle should be aware that the
breakup front is approaching. No overbank flooding has been
reported yet. However as the breakup front moves downstream, it is
likely that small jams may form and release, leading to
fluctuating water levels and potential minor or moderate flooding.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Flood Watch for AKZ833.
PK...Small Craft Advisory for PKZ801.
     Heavy Freezing Spray Warning for PKZ801-802-806-810-816-850-851.
     Small Craft Advisory for PKZ802.
     Heavy Freezing Spray Warning for PKZ803-804-852.
     Heavy Freezing Spray Warning for PKZ805.
     Gale Warning for PKZ806-807-854.
     Gale Warning for PKZ810.
     Gale Warning for PKZ811-857.
     Brisk Wind Advisory for PKZ812.
     Small Craft Advisory for PKZ816-851.
     Brisk Wind Advisory for PKZ817.
     Small Craft Advisory for PKZ850.
     Brisk Wind Advisory for PKZ853.
     Gale Warning for PKZ856.
     Brisk Wind Advisory for PKZ858.
&&

$$