137
FXAK69 PAFG 041154
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
354 AM AKDT Sat May 4 2024

.SYNOPSIS...
A series of upper level disturbances moving across the mainland
over the next several days will support isolated to scattered rain
and snow showers south of the Brooks Range and snow north of the
Brooks Range. Strong northeast winds persist through Sunday from
Cape Lisburne through the Bering Strait to St Lawrence Island.
Areas of blowing snow reducing visibility to one half mile or less
expected for the eastern Arctic Coast and Brooks Range through
Sunday morning. Strong and gusty southerly winds in the Alaska
Range passes combine with low relative humidity values to produce
Red Flag conditions near Delta Junction and Fort Greely this
afternoon. Flood Watches remain in effect for the Yukon River at
Circle as well as along the Tanana River from Salcha to Fairbanks.
A Flood Advisory is in effect for the Tanana River near the Rosie
Creek Subdivision.

&&

.DISCUSSION...
Synoptic Analysis and Forecast...
Aloft, at 500 mb, a longwave trough extends southwest from the
northern Canadian Archipelago to the central Aleutians, with
several closed lows in the flow, one centered 200 NM north of
Kaktovik, another centered between the Pribilofs and Cold Bay, and
the third over the western Kamchatka Peninsula. Meanwhile, weak
ridging remains over the eastern Interior and eastern Siberia. The
northernmost low elongates and weakens through Sunday, while a
piece of energy breaks off and develops into a new low near the
Bering Strait Sunday. As this new low pushes south of the Bering
Strait, the low that was southeast of the Pribilofs moves
southeast to the Gulf of Alaska and weakens through Monday. The
low over western Kamchatka moves southeast of the Aleutians into
the northern Pacific.

At the surface, a 986 mb low 100 NM east of the Pribilofs moves
east to the Alaskan Peninsula and weakens to 989 mb by Saturday
afternoon, continuing east to be 991 mb near Kodiak Sunday morning
and 992 mb in the central Gulf of Alaska by Sunday afternoon. A
1033 mb 600 NM north of Utqiagvik this morning dives southwest to
be 275 NM northwest of Utqiagvik Sunday morning and weakens to
1028 mb. The high pressure slowly shifts eastward through Monday
to be centered 250 NM north of Utqiagvik. Weak troughing will
persist north of the Alaska Range.

Models...
The 04/00Z models initialized fair against the 00Z RAOBS are in
agreement with the overall synoptic pattern. Differences in the
details aloft begin to emerge late Saturday into Sunday with the
closed upper level low that develops and moves southwest across
the Bering Strait. The GFS is the slowest and furthest northeast
with the low by Sunday afternoon centered near Kivalina, while the
ECMWF, NAM, and Canadian are clustered over the Bering Strait. By
Monday morning through, the spread among deterministic solutions
increases greatly in the placement of the low as it moves south of
St Lawrence Island, elsewhere, models are in fair agreement. At
the surface, by 06Z models underestimated the pressure gradient
over the Bering Strait and St Lawrence Island to Point Hope by 2
to 3 mb, resulting in winds overachieving. Adjusted winds up by a
couple of knots out west to account for the tighter gradient.
Otherwise, went with a general model blend for this forecast
package, with hand edits for winds and RH in the Alaska Range to
Delta Junction.

North Slope and Brooks Range...
A series of upper level disturbances will support periods of snow
across the North Slope and Brooks Range through early next week.
A disturbance moving west across the Arctic Coast and Brooks Range
through Sunday will bring accumulating snow of 2 to 3 inches
accompanied by northeast winds of 25 to 30 mph with gusts up to 45
mph possible for the eastern Arctic Coast and the Brooks Range.
These gusty winds will produce periods of blowing snow, reducing
visibility to one half mile or less at times and Winter Weather
Advisories remain in place through noon Sunday. Winds diminish
Sunday afternoon over these areas. Over the northwest Arctic Coast
northeast winds of 30 to 40 mph will persist through Sunday night
from Point Lay west, with lighter winds anticipated Monday.
Temperatures trend upwards.

West Coast and Western Interior...
Upper level troughing remains the dominant player, supporting
isolated to scattered rain and snow showers through the weekend
and into early next week. Snow accumulations will generally be
light and along the coast and northwestern Interior. Across much
of the western Interior, precip will take the form of rain. Tight
pressure gradient persists through the Bering Strait through
Monday, resulting in northwest winds of 30 to 40 mph stretching
from Point Hope to the Bering Strait to St Lawrence Island,
further south, northwest winds of 20 to 30 mph expected along the
coast. Despite the strong winds, areas of blowing snow will be
limited to areas where falling snow is occurring. Elsewhere,
visibility will likely stay above a mile due to a crust on the
snowpack.

Central and Eastern Interior...
Gusty southerly gap flow is ongoing in the Alaska Range this
morning with gusts up to 60 mph expected in the eastern Alaska
Range passes today, diminishing this afternoon. Issued a Wind
Advisory for the eastern Alaska Range through 4 pm today. The
gusty winds combined with low relative humidity values will result
in red flag conditions for areas near Delta Junction and Fort
Greeley today. An upper level disturbance pushing northwest across
the northern Interior and Brooks Range will support scattered
showers today, primarily north and west of a line from Chalkyitsik
to Livengood to Tanana. Another disturbance pushing northwest out
of the Yukon Sunday evening and Monday will bring another round
of showers across the Interior and increasing northeast winds.
Temperatures remain warm today slowly cooling Sunday and Monday.

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...
Red Flag Warnings remain in effect for areas near Delta Junction
and  Fort Greeley this afternoon, where low relative humidity
values combine with strong southerly gap winds in the Alaska
Range. Gusts of 30 to 50 mph (up to 60 mph in the eastern AK Range
passes this morning) are expected with relative humidity values
falling to near 20 percent this afternoon. Winds diminish by late
this afternoon. Rain and snow showers will be possible from early
the mid week with slightly cooler temperatures and higher humidity
values.

&&

.HYDROLOGY...
The Yukon River broke up at Eagle Friday afternoon, and the
breakup front is now at the Tatonduk River. The breakup front will
likely be in Circle between Sunday afternoon and Monday afternoon
and a Flood Watch remains in effect for Circle through Monday
afternoon. A Flood Watch remains in place for the Tanana River
from Salcha to Fairbanks as flooding due to snowmelt remains
possible. A Flood Advisory remains in effect for the Tanana River
near the Rosie Creek subdivision, where water is encroaching on
some roads.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Wind Advisory for AKZ849.
     Red Flag Warning for AKZ937-949.
     Winter Weather Advisory for AKZ804-805-808-810.
     Flood Watch for AKZ833.
     Flood Watch for AKZ840-844.
     Winter Weather Advisory for AKZ809.
PK...Small Craft Advisory for PKZ802.
     Brisk Wind Advisory for PKZ803.
     Small Craft Advisory for PKZ804-852.
     Brisk Wind Advisory for PKZ805.
     Heavy Freezing Spray Warning for PKZ806-816.
     Gale Warning for PKZ806.
     Gale Warning for PKZ807.
     Brisk Wind Advisory for PKZ809-812-814-850-853-858.
     Gale Warning for PKZ810.
     Gale Warning for PKZ811-857.
     Brisk Wind Advisory for PKZ813-859.
     Brisk Wind Advisory for PKZ815.
     Gale Warning for PKZ816-851.
     Gale Warning for PKZ817-854-856.
     Brisk Wind Advisory for PKZ855.
     Brisk Wind Advisory for PKZ860-861.
&&

$$