Blizzard in Alaska, May 16, 2023

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
332 AM AKDT Tue May 16 2023

.SYNOPSIS...
A very active weather pattern continues over Northern Alaska with
ice jam flooding impacting communities along the Yukon River as
well as other large rivers in Alaska. A storm along the West Coast
is bringing an mix of heavy snow at higher elevations and heavy
rain at low elevations while strong chinook winds along the
foothills of the Alaska Range will continue into Tuesday and
combined with low relative humidity levels are producing Red Flag
conditions along portions of the northern foothills of the Alaska
Range. Interior temperatures will be above normal again today
before falling behind a front moving east out of the Western
Interior on Wednesday.

&&

.DISCUSSION...

Upper Levels and Analysis... Aloft at 500 mb A deep upper level
low over the pole anchors a deep longwave trough extending south
along the dateline and into the Central Bering Sea while a strong
ridge holds fast over Western Canada northward into the Yukon and
Eastern Alaska. A second upper level low currently located over
Bristol Bay will push north today into the Lower YK Delta.
Moisture along and ahead of a front extending south of the low
along the West Coast of Alaska will funnel moisture north along
the Coast, the Western Interior and the Western Brooks Range into
Thursday. High pressure aloft will remain over the Eastern
Interior. Leeward side troughing along the northern foothills will
combine with a thermal trough over the southern Interior to
produce gusty winds over the Interior especially to the south of
the Yukon River this afternoon and evening. An areas of winds at
925 mb ahead of a front moving east out of the Western Interior
will aid in the gusty winds. Expect wind gusts in the 25 to 35 mph
range with a few gust over 40 mph this afternoon. A Wind Advisory
has been issued for the middle tanana Valley including the
Fairbanks Area from late this afternoon into this evening. Wind
advisories remain in effect for the the Central and Eastern Alaska
Range as well as the Delta Junction area. The strong winds will
combine with low relative humidity levels to produce Red Flag
conditions for the Eastern Alaska Range north of Donnelly Dome to
Deltana and the Tanana Flats near Delta Junction. Winds are
expected to diminish late tonight and moisture increase as a
front from the Western Interior moves into the area and ends the
warm and dry chinook conditions. Much cooler temperatures and
higher humidity levels are expected in these areas on Wednesday.

Central and Eastern Interior...
One more day of warm and windy before winds diminish on Wednesday
and the dry chinook pattern shifts to a more wet and cooler
pattern. A wind advisory has been issued for the Middle Tanana
Valley as 925 mb winds ahead of a strong front moving east out of
the Western Interior combined with a merging thermal trough and
leeward side trough will produce wind gusts in the 30 to 40 mph
range late this afternoon and into the evening including the
Fairbanks area. Wind Advisories remain in effect until Wednesday
morning along northern foothills of the Alaska Range northward to
near Delta Junction. The strong and gusty winds will combine with
low relative humidity levels along and near the Alaska Range to
produce Red Flag Conditions again today and into this evening.
There is just enough instability in the atmosphere ahead of the
approaching front for some very isolated thunderstorms from near
Bettles to near Nenana this afternoon and evening.

West Coast and Western Interior...
The arctic front will shift westward today, bringing rain with
widespread snowfall on the colder side of the storm. Accumulating
snowfall is expected pretty much everywhere along the West Coast,
with the heaviest amounts along the Seward Peninsula and Saint
Lawrence Island north to the Lisburne Peninsula, where 3 to 6
inches of snowfall are likely. Strong gale force north winds will
accompany the snow as the low shifts north and rapidly deepens
today, with gusts along the coast up to 60 mph. Significant
blowing snow is possible from Saint Lawrence Island to Wales to
Point Hope. See current winter storm warning and advisory products
along the Bering coast for more details.

The low weakens tonight and Wednesday with gradually diminishing
winds and snowfall out west. Showers over the Interior will
continue through Wed night before warming and drying commences Thu
and Fri.

North Slope and Brooks Range...
The arctic front is currently stalled over the North Slope
continues to produce snowfall across most of the entire Brooks
Range and N Slope where 48 snow totals of 2-5" are expected. Winds
remain onshore and light thus expect a return to normal temps
through Thu.

Extended Forecast Days 4-7...
Friday and beyond, confidence is now high that a low deep in the
Gulf of AK and a ridge across the Yukon and BC will begin to build
into the Interior. This should usher in warming temps and dry
conditions Friday through Sunday. Interior locations will likely
begin to see 70 degree temps for high temps by the weekend.
Showers will start to be possible by Monday as easterly waves
undercut the ridging.

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

&&

.FIRE WEATHER...
One more day of chinook weather conditions, with Tuesday expected
to be slightly windier warmer and drier across the Southeast
Interior and Tanana Valley, as well as across the AK Range. Thus
the red flag warning was continued into Tuesday night. Isolated
thunderstorms are also possible across most of the Central
Interior and may push into the White Mtns/Yukon Flats, but the
best chance is farther west.

Wednesday, much cooler temperatures and weaker winds, with an end
to the Chinook pattern and red flag conditions.

&&

.HYDROLOGY...
Flood warning is in effect for Stevens Village for ice jam flooding.
Flood watch remains in effect for high water possible from ice jam
flooding along the Yukon River from the Dalton Highway Bridge to
Rampart. The flood watch for ice jams for McGrath is no longer in
effect based on the latest river observations. A flood watch is no
longer in effect for the upper Chena River for snowmelt, however,
waters will remain elevated as snow continues to melt.

We will continue to monitor the Yukon River as the breakup front
progresses down river through the Yukon Flats, Stevens Village
and further downriver to Rampart.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Winter Storm Warning for AKZ213.
     Flood Watch for AKZ220.
     Red Flag Warning for AKZ223-226.
     Wind Advisory for AKZ222-223-225-226.
     Winter Weather Advisory for AKZ207.
PK...Gale Warning for PKZ806-816.
     Gale Warning for PKZ807.
     Brisk Wind Advisory for PKZ810.
     Heavy Freezing Spray Warning for PKZ811-817-854.
     Gale Warning for PKZ811.
     Brisk Wind Advisory for PKZ812.
     Heavy Freezing Spray Warning for PKZ816-851.
     Gale Warning for PKZ817.
     Small Craft Advisory for PKZ850.
     Gale Warning for PKZ851.
     Brisk Wind Advisory for PKZ853.
     Gale Warning for PKZ854.
     Gale Warning for PKZ856.
     Brisk Wind Advisory for PKZ857.
     Brisk Wind Advisory for PKZ858.
&&