035
FXAK69 PAFG 290933
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
133 AM AKDT Sat Jun 29 2024

.SYNOPSIS...
Temps are warming back up for the Interior this weekend as a
ridge aloft builds in from the Yukon. Thunderstorms for the next
few days will mainly be focused over the E Interior and the higher
elevations of the Alaska Range and Brooks Range. Fire smoke will
continue to be an issue, especially across parts of the Yukon
Flats and the S Interior.

&&

.DISCUSSION...

Upper Levels and Analysis...
There is a 567 dam upper level ridge over the Yukon Territory with
that ridge axis extending east into the E Interior and up to the
E Brooks Range. There is a large 534 upper level low over the
Bering Sea. There is a weak energetic wave aloft over the center
of the Mainland lifting northeast into the Yukon Flats. Some
elevated overnight thunderstorms continue along this boundary,
mainly over the Brooks Range and another area down over the SE
Interior. There is a thermal low near Old Crow at about 1005 mb,
with a second weaker trough over the SE Interior at 1009 mb.

Model Discussion...
Models are in excellent agreement with the larger scale pattern.
We will favor a NAM nest for winds blend, and a blend to the
GFS/EC for the remainder of the details, which really do not show
divergence until late Tuesday as a pattern changing low begins to
move toward the NW Arctic.

Central and Eastern Interior...
Temps are warming back up again this weekend as ridging aloft
rebuilds over the Mainland. Isolated thunderstorms the next few
days will generally be over the E Interior and along the E Brooks
Range and E Alaska Range. Most of the lower elevation valleys will
be shower and thunderstorm free this weekend, so it will be fairly
warm where smoke is not an issue. However, smoke will be an issue,
especially over parts of the S Interior with hot temps, and fairly
weak steering winds. On Monday, as the upper ridge breaks down,
temps go back down a few degrees and west winds increase, with
more afternoon thunderstorms over the higher terrain. Some storms
will drop into the S Interior valleys with a NW steering flow.
Smoke will likely get ventilated off to the east on Monday, so it
may improve air quality a bit.

West Coast and Western Interior...
Showers over the YK Delta to the S Interior will continue today
around a large low stationed over the Bering Sea today, with
another area of isolated thunderstorms over the W Brooks Range
this afternoon. Sunday warms up and a thermal low will be the area
of focused thunderstorms, from the tip of the Alaska Range
through the Lower Yukon Valley. An area of storms may move all the
way to the E Norton Sound and YK Delta coast given the easterly
steering flow. Some of these storms will be fairly strong and may
produce small hail and gusty winds with copious lightning. Monday
is another warm day, with increasing westerly winds as a low
approaches the NW Arctic.

North Slope and Brooks Range...
Today, northwest onshore winds shift east as a low forms over the
E Brooks Range. This location will be the area of focused
thunderstorms and some heavy rain showers, although isolated
thunderstorms will be expected over the entire spine of the
Brooks Range. Isolated thunderstorms are again possible Sunday,
but the north winds will continue to slowly stabilize the airmass,
with bouts of stratus and cooler temps along the coast. After some
warm days and thunderstorm action over the arctic plain, this will
end with a more normal pattern in place. Southwest winds increase
late Monday as a front moves up to the NW Arctic coast.

Extended Forecast Days 4-7...
The numerical models are really changing their tune for next week,
whereas prior model runs from the global models a few days ago
built in a large blocking high over the Mainland, they are now
keeping the subtropical high out over the Bering, with ridge
riding strong troughs moving across the N Mainland and Arctic.
This is a fairly large pattern shift and will usher in a major
change in weather beginning Tuesday, as a front from E Siberia
moves inland across the NW Arctic and shifts east along the Brooks
Range and eventually into the Interior through the remainder of
the week. This will bring increasing west-southwest winds across
the Mainland each day, with increasing chances for rainfall and
cooler temps.

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


&&

.FIRE WEATHER...
More stable air is in place over the Western to Central Interior
with the axis of instability/thermal low situated over the E
Interior. Today is warming again, by a few degrees, with minimum
RH falling again as well. Isolated to widely scattered
thunderstorms will be focused over the far E Yukon Flats and E
Brooks Range today, as well as the Fortymile Uplands. Sunday, the
thermal trough strengthens over the S Interior from McGrath all
the way to the ALCAN border. There will be a region of strong
widely scattered thunderstorms focused over the SW Interior to the
Lower Yukon, and another area over the Upper Tanana to the
Fortymile. Both areas will need to be monitored for possible
scattered thunderstorm potential. Sunday is warmer everywhere
else and likely the hottest overall day for most of the Mainland.

Monday is warm again but less hot, with increasing westerly winds.
Some storms will be strong once again over parts of the S Interior
with storm motions possibly pushing storms over the Tanana
Valley.

Major pattern shift begins Tue and Wed as the upper ridge breaks
down and a strong front moves into the NW Arctic and shifts east
through the week, bringing potential wetting rains and much cooler
temps, although strong southwest winds may create some critical
fire weather conditions prior to that. Stay tuned...


&&

.HYDROLOGY...
Heavy rain showers and thunderstorms over the Brooks Range may
feed into faster moving streams and cause rapid rises, which will
remain high into this weekend. 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 AKZ834-839>845.
PK...None.
&&

$$

Ahsenmacher