172
FXAK69 PAFG 251447
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
647 AM AKDT Tue Jun 25 2024

.SYNOPSIS...
A very active pattern will bring the warmest temperatures so far
this Summer to much of the Interior on Wednesday and Thursday
while a highly unusual Bering Sea low pressure system brings near
Gale force winds to the Yukon Delta coast on Wednesday. The heat
wave will even extend to the North Slope on Wednesday and
Thursday, bringing near record high temperatures to that area.
Thunderstorms will continue to be active this week, with
relatively dry thunderstorms possible east of Chena Hot Springs
on Wednesday evening. Thursday and Friday also look to be very
active thunderstorm days across Northern Alaska.

&&

.DISCUSSION...

Analysis and Model Discussion...Aloft at 500 mb, a tight closed
low is retrograding northward off the Arctic Coast as a strong
ridge builds over the central and eastern Interior. A vertically
stacked low has now entered the western Bering Sea near Attu. This
feature will track along the western Aleutians to near Adak then
turn northward, reaching St. Paul Island Wednesday afternoon. As
the low continues to drift north Thursday and Friday, a sharp
convergence zone will form along the boundary between the ridge
over the Interior and the low in the Bering Sea. This will serve
as a focus areas for scattered thunderstorms on Thursday and
Friday afternoons and evening. Thunderstorms will likely even
drift north of the Brooks Range, especially west of Umiat. With
the center of the high moving over the eastern Arctic Coast by
Thursday afternoon, expect very warm temperatures all the way up
to the Arctic Coast Wed/Thu/Fri.

Another impactful feature will be a shortwave rotating to the
southwest around the center of the upper level ridge centered over
the Yukon Flats on Wednesday afternoon. With dry air at the
surface, elevated instability, and lifted condensation levels as
high as 8500 feet, this will likely produce widely scattered dry
thunderstorms over the Fortymile Uplands and upper Tanana Valley
Wednesday afternoon.

Models initialized quite well when compared to obervations at the
surface and aloft. We will use a blend of models for the forecast
today and make a few notable changes in the Lightning Activity
Level forecast including increasing thunderstorm coverage to
scattered on Thursday across a large area from the Alcan border to
Fairbanks to Huslia to the Western Brooks Range. We also increased
rainfall amounts on Thursday in the area that we expect
thunderstorms. We`ll also increase thunderstorm coverage to
widely scattered today across the White Mountains, and increase
easterly winds across the northern Interior on Thursday.

Central and Eastern Interior...Hot and dry conditions with
afternoon and evening thunderstorms continue today with highs
reaching the low to mid 80s. Wednesday will be the hottest day of
the week with highs in the upper 80s to near 90. Thursday will be
slightly cooler, but expect an increase in thunderstorm activity
especially south and west of the Yukon Flats.

West Coast and Western Interior...Warm and mostly dry conditions
persist. With a strong low pressure system approaching in the
Bering Sea Wednesday and Thursday, expect southeast winds 15 to
25 mph from Nome south late tonight and Wednesday. The front will
bring little in the way of precipitation with only light rain
expected along the Yukon Delta. Thursday looks to be a very big
thunderstorm day from east of Kotzebue to Huslia and southeast.

North Slope and Brooks Range...Warm temperatures will extend north
all the way to the Arctic Coast on Wednesday and Thursday as the
ridge moves north over the Arctic Coast. Isolated thunderstorms
are expected even up to the Arctic Coast on Wednesday.
Thunderstorm activity will increase in the Brooks Range on
Thursday. East winds around 15 mph are expected tonight along the
coast.

Coastal Hazard Potential Days 3 and 4...The aforementioned low
pressure system in the Bering Sea will bring elevated surf 1 to 2
feet above the normal high tide line along the Yukon Delta coast
as well as south facing shorelines south of the Bering Strait
including Nome. Water will be elevated Wed-Fri with multiple water
level peaks as storm surge values remain fairly constant and
tides go in and out.

&&

.FIRE WEATHER...
A strong ridge aloft continues to build over Interior Alaska with
numerous shortwaves moving through the ridge providing instability
for thunderstorm activity. The most concerning of these shortwaves
will move around the high center from the north on Wednesday
afternoon and evening over the southeast Interior. With lifted
condensation levels as high as 8500 feet along with northeast
steering flow and surface RHs as low as 20%, this is an ideal
setup for dry thunderstorms. Dry thunderstorms will be possible
east of Chena Hot Springs, but most likely in the upper Tanana
Valley from Dot Lake east to the Alcan Border.

Today, expect near Red Flag conditions across the interior of the
Seward Peninsula and northeast to Buckland. Highs will mostly be
in the 80s in the Interior and in the mid to upper 70s out west
away from the immediate coastline with min RHs dropping into the
25-35% range. Winds will likely only reach 15 mph over the
interior Seward Peninsula this afternoon. Thunderstorms will be
isolated across the Interior and the Eastern Brooks Range and
widely scattered from McGrath to Livengood and east across the
White Mountains and Fortymile uplands.

Wednesday, in addition to the possibility of dry thunderstorms
described above, will be the hottest and driest day of the week
with highs expected to reach the upper 80s to near 90 across most
of the Interior. Min RHs will be 20-25% east of Tanana and
slightly higher to the west. Outside of the widely scattered dry
thunderstorms east of Chena Hot Springs, expect isolated
thunderstorms across the rest of the Interior.

On Thursday, the ridge will shift north to the Arctic Coast as a
strong low in the Bering Sea pushes further north. This will
tighten the gradient and cause east winds 10 to 20 mph across the
northern Interior. It will still be plenty hot and dry, so if the
winds pan out, could see Red Flag conditions for hot/dry/windy in
the northern Interior on Thursday. Thursday may also be the
largest lightning day of the year so far as scattered
thunderstorms are expected to form along a boundary between the
Bering low and the Interior ridge extending from the Western
Brooks Range to Fairbanks to the Alcan Border. Isolated
thunderstorms are expected even up to the Arctic Coast.

Friday will likely be another big thunderstorm day, with activity
at this time looking the most active over the Yukon Flats.

&&

.HYDROLOGY...
Glacial fed rivers including the Tanana are beginning to rise as
warming temperatures lead to increased high elevation snowmelt.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Dense Smoke Advisory for AKZ839-840-844.
PK...Small Craft Advisory for PKZ801.
     Small Craft Advisory for PKZ802-816.
     Small Craft Advisory for PKZ850.
     Small Craft Advisory for PKZ851.
&&

$$

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