Flood in Alaska, May 6 to 8, 2022

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
146 PM AKDT Fri May 6 2022

.SYNOPSIS...Isolated showers this evening and Saturday south of
the Brooks Range with some light snow or flurries from the Brooks
Range north. Additional snow accumulation along the Dalton Highway
from Atigun Pass north of around 2 inches. Fog and stratus will
continue to lift on the West Coast this evening with a weather
front spreading a mix of precipitation to the area by late
Saturday.

&&

.DISCUSSION...

Models...06/12Z solutions in good agreement through the weekend
as they bring a strong system to the West Coast, then have it
decay as it moves across the state with a mix of precipitation and
cooler temperatures. They stay in reasonable agreement through
the midrange, but are showing some significant differences in the
extended periods with the active pattern that is developing.
Precipitation remains limited for the near term with mainly
isolated showers in the Interior and on the West Coast with some
flurries or light snow in the Arctic. Will use a blend of the
solutions, but keep probabilities in the isolated/slight chance
range except for the north slopes of the Eastern Alaska Range
where snow is expected through Saturday morning. Thermal trough in
the Interior from Chicken to Ruby. Convective indicies are better
with lifted index around zero and non zero CAPE values during the
evening hours today and during the afternoon and evening
Saturday. Current temperature database looks good, just a few
minor adjustments to match current trends. Will use a blend for
the winds including the current database with a lean toward the
stronger Canadian solution for the short term.

Aloft...At 500 hpa...Broad troughing still dominates over the
Arctic with a 518 dam low 150 nm north of Wrangel Island with a
trough extending east, then south over Utqiagvik to Galena to
Russian Mission. A 533 dam low is over the eastern Brooks Range,
while the low that was over Nikolski has moved to 300 nm south of
Kodiak Island. Ridging has pushed in over the southwest mainland
to a 537 dam high over Denali, and northeast over the Chukchi Sea,
while the high near MacKenzie Bay is stationary 536 dam and
ridging has built northwest over the eastern Arctic. Saturday
afternoon the ridging over the Arctic will be pushed east over the
Beaufort Sea as a 520 dam low moves just east of Wrangel Island
and the low that was north of the Island moves northwest. The low
over the Eastern Brooks Range will remain stationary, while the
ridging that was pushing over the Chukchi Sea will rotate to the
southeast to lie over the south slopes of the Alaska range and the
southeast Interior. The low south of Kodiak will move southeast
over the Northeast Pacific. At 850 hpa...Temperatures will range
from around 0C to around -10C with the coldest temperatures in the
Arctic Plain, and the warmest in the Upper Tanana Valley.
Temperatures will warm slightly in the Interior through the
weekend.

Surface...High pressure continues to push east across the Arctic
and Arctic Coast with a 1025 mb high 450 nm north of Demarcation
Point. Broad low pressure continues south of the Brooks Range
with a 1005 mb low 200 nm south of Whittier. Thermal trough lies
from Chicken to Ruby, and a 1010mb bubble high has developed over
the Alaska Range. A 999 mb low has moved to 300 nm west of
Wrangel Island on the Siberian Coast, and high pressure is pushing
northeast across the Bering Sea to the Seward Peninsula. Saturday
afternoon the high in the Arctic will be 200 nm north of Banks
Island at 1030 mb, while the low pressure south of the Brooks
Range will be pushed east as the high pressure across the Bering
Sea, with a 1034 mb high near Atka, pushes into the Central
Interior. Weak troughing will lie from the Upper Tanana Valley to
Atigun Pass, then west to a 999 mb low 200 nm northwest of Point
Lay. By Sunday afternoon the high pressure will be pushed over the
southeast Interior as a strong 994 mb low moves to Shishmaref
with a cold front extending south across Kuskokwim Bay and pow
pressure pushing east across the Arctic Plain.

Arctic Coast and Brooks Range...Stratus will prevail with flurries
or light snow. Light snow in the Brooks Range with around 2 inches
of accumulation along the Dalton highway tonight, then some
clearing Saturday. Onshore to easterly flow will turn offshore
Saturday. Low clouds and areas of fog along the coast will start
breaking up as flow turns offshore. East winds 5 to 20 mph with
the strongest winds along the coast will turn from the southeast
to south tonight. Low tonight 5 above to around 20 above with
warmest in the Brooks Range. Highs Saturday will range from the
20s to upper 30s with the warmest in the Brooks Range.

West Coast and Western Interior...Stratus and fog along the coast
clearing this evening then a mix of clouds with a slight chance
of showers. Inland partly to mostly cloudy with a chance of
showers. Patchy morning fog Saturday. A weather front will move to
the coast by Saturday evening spreading a mix of precipitation to
the area with accumulating snow up to 2 inches locally. Winds
inland northwest to northeast at 5 to 15 mph while winds along the
coast will be north to northwest 10 to 25 kt with the strongest
winds in the Bering Strait and on St Lawrence Island. Lows tonight
will range from the teens to around 30. Highs Saturday will be
range from around 30 on the outer capes to 50 in the Middle Yukon
Valley.

Central and Eastern Interior...Isolated showers in the evening,
and again Saturday afternoon. A mix of rain and snow moving into
the area Sunday evening through Monday. Winds variable, mainly
east to northeast to 10 mph turning from the southwest late
Saturday. Lows tonight will range from the mid 20s to lower 30s,
coldest north of the Yukon River. Highs Saturday will range from
the mid 40s along the south slopes of the Brooks Range to around
60 in the Upper Yukon Flats, with 50s in the Middle Tanana Valley.

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

Extended forecast for days 4 to 7...A weather front will move
through the area spreading a mix of precipitation. A short break
between systems before another midweek spreads more rain and snow
across the area as a series of weather fronts will move across the
area. Temperatures cooler through the week. The Arctic will get
accumulating snow Monday and Tuesday with up to 3 inches of
accumulation in the Brooks Range.

&&

.Fire Weather...A few lightning strikes yesterday west of Manley
Hot Springs. Very limited lightning expected this evening and
again Saturday. The ground continues to dry and so do the dead
grasses. That will continue through the weekend, so use caution
around dead grasses as they can ignite easily when dry. Relative
Humidity will range from around 25 percent to around 40 percent
from the Yukon River south. There are no concerns at this time.

&&

.Hydrology...Rivers continue to clear up in the Middle Tanana
Valley with some minor ice flows moving downstream. The Yukon
River still has ice in place and it has not started to move at
Dawson YT yet. Middle Tanana Valley rivers will continue to run
high around bankfull as higher elevation meltwater makes its way
into the waterways. Locally meltwater flooding will continue. High
temperatures will be in the 50s through the weekend with lows
falling to around freezing. At this time there are no major
concerns, but things can change rapidly so be alert to changing
conditions. For the latest river information go to
www.weather.gov/aprfc.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...

None.

&&

SDB MAY 22