439
FXAK69 PAFG 281229
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
429 AM AKDT Fri Jun 28 2024

.SYNOPSIS...
Summer rolls on with more active thunderstorms today expected
from the Brooks Range south through the Yukon Flats and into the
Interior higher elevations. Red Flag Warnings for lightning
activity will remain in effect for the Yukon Flats and SE Brooks
Range foothills today. West winds increase today and will blow
smoke from the large fires over the S Interior farther northeast.
Slightly cooler today (a few degrees cooler) for parts of the S
Interior then slowly warming again for the weekend.

&&

.DISCUSSION...

Upper Levels and Analysis...
There is a 568 high centered over the Yukon Territory with a 538
dam low centered over the Bering Sea. In between there is a front
with several smaller scale ripples of energy moving north which
are continuing to support overnight thunderstorms from the Arctic
Coast near Utqiagvik and down through the Central Interior. The
Bering low is analyzed around 989 mb, which represents a -3.0
sigma anomaly. A thermal trough is situated over the Brooks Range,
with 850 temps of 14.0 C or higher pretty much blanketing a
region from Fairbanks north to the E Beaufort Sea. The coolest air
is over the Yukon Delta where there are rainshowers and temps in
the upper 40s. A surface cool front is already pushing northeast
across the S Interior, with west to southwest winds being seen at
McGrath.

Model Discussion...
The models are in pretty good agreement with the general pattern
as the upper ridge continues to weaken today, then gradually
rebuilds over the S Interior this weekend. In addition, a series
of weak fronts will move across the E Brooks Range and E Arctic
over the next few days which will gradually bring slightly cooler
air southward, by Monday. We favored a NAM nest/Canadian Regional
blend for winds to increase the west winds this afternoon over the
Interior, and a general GFS/ECMWF blend for everything else, which
includes adding in numerous thunderstorms to the Brooks Range
today.

Central and Eastern Interior...
Today will be continued hot over the Yukon Flats to the Fortymile
Country, but it will slightly cooler over the S Interior and
Central Interior today, with west winds this afternoon.
Thunderstorms will be active over the White Mtns northward, with
strong thunderstorms likely over the Yukon Flats and White Mtns,
as well as over the higher terrain of the Fortymile Uplands.
Isolated thunderstorms are expected over the S interior and into
the Central Interior, favoring the higher elevations, although a
band of more enhanced showers and thunderstorms will occur along
the cool front over the Central Interior to Upper Koyukuk Valley.

Ridging aloft gradually builds back in for the weekend with rising
temps back into the 80s, and much lower thunderstorm activity,
with that ridge aloft suppressing thunderstorm potential. Right
now, it looks mostly like thunderstorms will be relegated to the
AK Range and the Fortymile Uplands, as well as the upper Tanana
Valley this weekend. Steering flow and winds are fairly weak this
weekend, and with less precipitation chances and hotter temps
coming back, smoke looks to be widespread over parts of the S
Interior including around Fairbanks.

West Coast and Western Interior...
Showers will continue to rotate around the large Bering low along
the West Coast. Isolated overnight thunderstorms will continue
into this morning today over the W Interior to NW Arctic, with
more afternoon thunderstorms mainly over the Upper Kobuk Valley
north to the Brooks Range, with just some isolated spotty thunder
farther south toward the Alaska Range to the Kuskokwim Mtns.

The ridge aloft rebuilds west this weekend, so it will be warming
again over the Interior with 80s returning for Sunday. The
gradient will change to a more light north wind by this weekend.

North Slope and Brooks Range...
Another warm day today with more very active thunderstorm
activity, as a thermal low will remain parked over the Brooks
Range. Scattered to numerous thunderstorms will be possible from
the W Brooks Range east to Chandalar, with some storms being very
strong and capable of producing very heavy downpours, frequent
cloud to ground lightning, and hail up to half an inch. Northwest
winds will cool temps back down closer to normal values albeit
still warmer than average. Thunderstorms on Saturday will be
relegated to the Central and E Brooks Range, with drying
conditions expected by Sunday.

Extended Forecast Days 4-7...
By Monday, a narrow Mainland ridge aloft will still be in place,
but there will be a series of lows which will move overtop that
ridge, gradually weakening it and bringing wetter onshore flow to
the NW Arctic and down the West Coast Tuesday and Wednesday, with
those fronts moving inland by the latter half of the week. This
should allow for some relief from hot temps and may even bring
rain into the Interior.

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

&&

.FIRE WEATHER...
West winds will move across the Interior today, which will
represent a slightly cooler and more stable air mass from the
west. The thermal low will move into the Yukon Flats today, and
there will be widely scattered to scattered thunderstorms from the
White Mtns northward, with another area of widely scattered
thunderstorms over the Fortymile. Further west, it will be more
stable with only isolated thunderstorms, mainly focused over the
higher terrain like the AK Range. It will be warm today, but 3 to
5 degrees cooler over the S Interior and Central Interior. It will
remain hot and dry over the Yukon Flats with min RH near 20 % and
highs near 90.

By this weekend, the thermal trough shifts east toward the ALCAN,
with less thunderstorm activity overall, and no thunderstorms
expected from Fairbanks westward. Isolated to widely scattered
thunderstorms will be relegated to the E Brooks Range and
Fortymile Uplands, as well as the E AK Range. It will be getting
hot again this weekend as ridging aloft rebuilds, and temps go
above 80 again across the Interior. Smoke and air quality looks
like it will be getting pretty bad for the S Interior this
weekend, with winds becoming fairly light and temps rising.

&&

.HYDROLOGY...
Heavy rain showers and thunderstorms over the Brooks Range today
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...Red Flag Warning for AKZ911-933.
     Dense Smoke Advisory for AKZ834-839>841-844-845.
PK...Small Craft Advisory for PKZ801-802-850.
     Small Craft Advisory for PKZ853.
&&

$$

Ahsenmacher