232
FXAK69 PAFG 051227
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
427 AM AKDT Sun May 5 2024

.SYNOPSIS...
A series of upper level disturbances moving across the mainland
over the next several days will support rain and snow showers
south of the Brooks Range and snow north of the Brooks Range.
Strong northeast winds persist through Monday from Cape Lisburne
through the Bering Strait to St Lawrence Island. 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 south from the far
northern Canadian Archipelago across much of mainland Alaska and
into the Gulf of Alaska, with several closed lows in the flow. The
northernmost low is centered 125 NM northeast of Utqiagvik, the
second low is southeast of Kodiak, and the third is over the
southern Kamchatka Peninsula. Meanwhile, weak ridging remains over
the eastern Interior and eastern Siberia. The northernmost low
slides westward today becoming more elongated with a piece of
energy breaking off and developing into a new low over the Seward
Peninsula this afternoon and evening. As this new low pushes south
and west through the Bering Strait to the central Bering Sea by
Tuesday afternoon, the low that was southeast of Kodiak lifts
northeast and weakens as it moves onshore near Yakutat by Tuesday
morning, continuing north across the Upper Tanana Valley and
Fortymile Country and AlCan border Tuesday evening through
Wednesday. The low over western Kamchatka moves southeast of the
Aleutians into the northern Pacific.

At the surface, a 1027 mb high centered 275 NM northwest of
Utqiagvik slowly weakens through Tuesday as it moves to be
centered 200 NM north of Utqiagvik by Tuesday morning. A 990 mb
low near Kodiak weakens as it moves east into the central Gulf of
Alaska by Sunday afternoon. A weak 1012 mb low southeast of the
Gulf of Anadyr Monday afternoon deepens to 1008 mb as it moves
southeast to the Pribilofs by Tuesday afternoon. Weak troughing
will persist north of the Alaska Range.

Models...
The 05/00Z models initialized fair against the 00Z RAOBS and are
in agreement with the overall synoptic pattern. Differences in
the details aloft emerge quickly with the closed upper level low
that develops and moves southwest across the Bering Strait. By
Monday afternoon the 00Z ECMWF is the outlier as it is the
farthest north (still north of the Bering Strait) and the deepest
(509 dam), while the NAM, GFS, and Canadian are clustered near St
Lawrence Island and similar in strength of around 518 dam. By
Tuesday afternoon, the ECMWF catches up with the other models and
has the low located near St Matthew Island, but remains the
deepest the solution. At the surface, models initialized well
against the 00Z and 06Z surface observations. The largest
difference between model solutions becomes evident by Monday
morning with the placement of the high over the Arctic Ocean. The
ECMWF is the furthest north with the high with the GFS the
furthest south and the NAM and the Canadian in between, but the
models concur on the strength. Adjusted winds up by a couple of
knots across the Interior for this afternoon and evening to
account for a tighter gradient and bumped up winds slightly in the
Alaska Range passes Monday and Tuesday. Otherwise, went with a
general model blend for this forecast package.

North Slope and Brooks Range...
A series of upper level disturbances will support periods of snow
across the North Slope and Brooks Range through mid week. Snow
amounts will be light. Over the northwest Arctic Coast northeast
winds of 30 to 40 mph will persist through Monday from Point Lay
west, with lighter winds anticipated Tuesday. Elsewhere along the
coast northeast winds of 15 to 25 mph are expected through Monday,
diminishing Monday night. Temperatures trend upwards.

West Coast and Western Interior...
Troughing aloft remains the dominant influence. This will support
isolated to scattered rain and snow showers through mid-week as
pieces of energy rotate through the flow. Across the Interior,
much of the precip will be in the form of rain, while across the
northwestern Interior and along the coast, precip will likely be
snow north and a rain snow mix south. Snow accumulations of less
than an inch. A strong pressure gradient persists from Point Hope
through the Bering Strait to St Lawrence Island today, supporting
northwest winds of 30 to 40 mph. Further south, northwest winds of
20 to 30 mph expected along the coast. Visibility reductions in
blowing snow were very limited yesterday and expect that to
continue today, given the crust on the snowpack. Slightly cooler
temperatures expected today, primarily along the coast.

Central and Eastern Interior...
Fairly quiet conditions expected across the Central and Eastern
Interior today, with a few showers not out of the question. North
to northeast winds increase into the 10 to 20 mph range this
afternoon and evening, with the strongest winds occurring in the
White Mountains and Interior summits; across the Tanana Flats to
Delta Junction winds will be more northwesterly. An upper level
disturbance pushing northwest out of the Yukon this evening and
Monday will bring another round of showers across the Interior,
with snow and rain-snow showers possible during the early morning
hours Monday. Snow accumulations will be light. Another piece of
energy will lift northwest out of the Yukon on Tuesday. Weak
southerly gap flow develops in the Alaska Range passes Monday
afternoon, continuing into Wednesday. Temperatures cool today and
Monday before warming again Tuesday.

Extended Forecast Days 4-7...Upper level troughing over the Bering
Sea remains the dominant player through the end of the work week,
while ridging builds north into British Columbia. This set up
supports scattered showers across northern Alaska. Temperatures
slowly trend upwards for the latter half of the week.

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 and Monday
before warming up again Tuesday. Minimum relative humidity values
largely remain above 25 percent through Tuesday. North to
northeast winds increase into the 10 to 20 mph range this
afternoon from the Yukon Flats south to the White Mountains,
Fortymile Country and Middle Tanana Valley, with the strongest
winds occurring in the White Mountains and Interior summits. Weak
southerly gap flow develops in the Alaska Range passes Monday
afternoon continuing into Wednesday.

&&

.HYDROLOGY...
The Yukon River broke up at Eagle Friday afternoon. As of late
Saturday afternoon, ice is jammed roughly 28 to 30 miles upstream
from Circle. There is a 20 mile run of dense ice above the
breakup front, and should arrive near Circle early this morning if
the breakup front does not stall. Small ice jams may be possible
as the breakup front moves downstream leading to minor or moderate
flooding.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Flood Watch for AKZ833.
     Flood Watch for AKZ840-844.
PK...Small Craft Advisory for PKZ801.
     Heavy Freezing Spray Warning for PKZ801>803.
     Small Craft Advisory for PKZ802.
     Small Craft Advisory for PKZ803.
     Small Craft Advisory for PKZ804.
     Heavy Freezing Spray Warning for PKZ804-850.
     Small Craft Advisory for PKZ805-852.
     Heavy Freezing Spray Warning for PKZ805-806-810-811-816-851.
     Gale Warning for PKZ806-811-854-856.
     Gale Warning for PKZ807.
     Brisk Wind Advisory for PKZ809.
     Gale Warning for PKZ810.
     Brisk Wind Advisory for PKZ812-853-858.
     Brisk Wind Advisory for PKZ813-859.
     Brisk Wind Advisory for PKZ814-860.
     Brisk Wind Advisory for PKZ815-861.
     Gale Warning for PKZ816.
     Gale Warning for PKZ817.
     Small Craft Advisory for PKZ850.
     Gale Warning for PKZ851.
     Heavy Freezing Spray Warning for PKZ852.
     Brisk Wind Advisory for PKZ855.
     Gale Warning for PKZ857.
&&

$$