190
FXAK69 PAFG 020942
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
142 AM AKDT Tue Jul 2 2024

.SYNOPSIS...
A strong front from Siberia is moving into the NW Arctic Chukchi
coast this morning, and will continue to move east for the next
few days. This will bring a pattern shift with gradually cooling
temps, blustery southwest winds, and increasing rain chances. The
current forecast looks fairly wet for most of the Mainland for the
4th of July. Fires will be prone to the southwest winds the next
couple days, but after that, rains will be moving over a vast
majority of them, so smoke and air quality should be improving
vastly for most locations after today.

&&

.DISCUSSION...

Upper Levels and Analysis...
There is a very narrow upper ridge axis over the center of the
Mainland stretching from the Norton Sound to the E Interior, with
the center of that ridge around 570 dam. There is a 552 dam upper
low over the AKPEN moving east into the Gulf of AK. There is a
536 dam mobile low moving east from E Siberia. There is a
departing 522 arctic low over the Canadian Archipelago. A subtle
shortwave trough is traversing over the ridge axis across the
Yukon Flats and Fortymile, with continued elevated thunderstorms
ongoing as of early this morning.

Model Discussion...
The numerical models remain fairly tightly clustered with the
general pattern and timing of the front moving in from Siberia,
and its eastward track by Thursday. More rainfall coming in behind
this leading front is still expected for the 4th, along with
strong southeast winds preceding it and behind it. A NAM nest
blend was favored to capture the strong southwest through Thu. A
blend of models was favored for precipitation timing and the
general trend of cooling temps after today.

Central and Eastern Interior...
Isolated showers and thunderstorms are still ongoing over the
Fortymile this morning, and some showers will continue this
morning over parts of the Tanana Valley, but overall, it`ll be dry
with warming temps over the S Interior from yesterday, and still
warm over the N Interior. Southwest winds increase today and will
be 10 to 15 mph over most of the Interior, 15 to 25 over the N
Interior with some gusts to 30+ over the Yukon Flats northward.
Isolated afternoon thunderstorms look fairly meagre but there
will be some over the E Interior again today, but less than the
last few days, by a lot.

Wednesday is breezier with gusts to 25 mph over the Interior,
and close to 40 to 45 mph over the N Interior N of the White Mtns.
Rain is already ongoing over the Upper Koyukuk and transitions
south through the day, reaching the S Interior by the afternoon
and evening. Rainfall will be generally light and will favor
upslope areas in westerly flow. Periods of light rainfall continue
into the 4th and then a good slug of subtropical moisture will
bring in widespread moderate rain to the entire Interior Thursday
afternoon and evening. It looks straight wet and blustery, quite
fitting for the 4th, don`t you say? After a month of heat and
mostly dry, it will be quite the change. Rain is tapering off by
Friday morning, and will likely continue as on/off showers through
the latter half of Friday. Temps are a solid ten degrees below
seasonal norms by the end of the week for most of the area.

West Coast and Western Interior...
A strong gale force front is moving into the NW Arctic early
this morning, and then shifts inland Tuesday evening from Norton
Sound northward. This front will bring a continuous period of
southwest winds to 25 to 35 mph and periods of rainfall through
the weekend. Rainfall amounts will be 2 to 4 inches over the SW
Brooks Range with a general 1 to 2 inches elsewhere, by late
weekend. In addition, expect elevated water levels of 2 to 3 feet
and high wave action along the West Coast, from Norton Sound to
the Chukchi coast. Temps are trending down quite a bit through the
week.

North Slope and Brooks Range...
South winds associated with a fast moving front have reached
Wainright along the Chukchi coast, and this will quickly move east
today, bringing southwest winds 15 to 30 mph and rainfall, which
will reach the E Arctic and Brooks Range by tonight. Mountain
gaps in the W and Central Brooks Range will see wind gusts to 50
mph. For N Slope and Arctic coast standards, there will be fairly
moderate to heavy rain at times. There will be a break in
rainfall with intermittent showers Wednesday night into Thursday
before more rainfall commences into Friday and Saturday. Rainfall
amounts will range from 2 to 4 inches over the W brooks Range to
0.5 to 1 inch elsewhere, with 1 to 2 inches over the E Brooks
Range.

Extended Forecast Days 4-7...
Friday, global ensemble clusters are all depicting a general
west-southwest pattern over the West Coast with troughs
overtopping a strong 594 subtropical high over the Central NPAC.
This means it will be cooler and wetter for the Mainland through
the weekend. Thereafter, as usual, divergence begins as some
model clusters and ensembles want to amplify the flow as a cutoff
NPAC low gets caught up into the broader scale pattern early next
week. That could bring the Mainland back to a fairly typical
trough out west and southerly flow aloft out east. We shall see.
Either way, cool through the weekend and then maybe some
moderation for the E Interior next week.

Coastal Hazard Potential Days 3 and 4...Strong southwest winds to
gale force will bring elevated water levels of 2 to 3 feet above
the normal high tideline from Norton Sound to the Chukchi coast
beginning Tue and lasting into late week.

&&

.FIRE WEATHER...
Southwest winds are already ramping up overnight across the W
Interior ahead of a front moving into the NW Arctic. There remains
some clouds over the S Interior this morning, along with some
showers over the Fortmile and even a few isolated overnight
thunderstorms along the remnant thermal trough. Today, any wet
isolated thunderstorms looks relegated to the E Interior closer to
the ALCAN, with general showers elsewhere.

Otherwise, significant fire weather conditions ramp up today
which is drying back out some with increased southwest winds of 10
to 15 mph over most of the Interior, and 15 to 20 mph over the N
Interior, and 15 to 25 mph with gusts near 35 mph over the Yukon
Flats and Upper Koyukuk Valley. Critical fire weather conditions
look likely over the northern half of the Interior, as temps will
be around 75 to 80, and minimum RH in the upper 20s to near 30 %,
thus a red flag warning is now in effect for the N Interior zones
from the Dalton Hwy east. There is no change in thinking here,
with the strongest core of winds being north of the White Mtns,
but it will be gusty from the southwest pretty much everywhere
with drying and enhanced mixing by afternoon.

The gradient continues to increase overnight, thus winds will only
weaken partially and likely remain mixed out from the Fairbanks
area northward. Winds on Wednesday are stronger yet, with
widespread 15 to 20 mph, and 20 to 25 mph and gusts to near 45
mph over the Yukon Flats and Dalton Highway corridor, and into the
S Brooks Range slopes. However, temps are falling and
precipitation will be possible by Wednesday afternoon in the form
of rainfall, so minimum RH looks to be higher, into the upper 30
to mid 40 % range.

The onset of wetting rains looks fairly low through Wednesday
midday, with increasing chances by Wednesday evening and overnight,
and high chances on Thursday and Thursday night. The lone holdout
will be the Yukon Flats which will see downslope drying and
little in the form of rainfall until maybe Thu night.

&&

.HYDROLOGY...
Glacial fed rivers including the Tanana are slowly rising as
warming temperatures lead to increased high elevation snowmelt and
glacial melt.

Beginning next week around Wednesday, heavy rainfall will move
across the W Brooks Range with 2 to 4 inches of rainfall through
next weekend, with 0.75 to 1.5 inches over parts of the Interior.
Expect river rises with this amount of water across the Mainland.
Expect significant rises on rivers draining the Brooks Range
including, but not limited to, the Wulik, Kobuk, Noatak, and
Koyukuk Rivers and smaller creeks and streams.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...

AK...Red Flag Warning for AKZ911-932-933.
PK...Small Craft Advisory for PKZ801-804-855.
     Small Craft Advisory for PKZ802-803-808-852.
     Small Craft Advisory for PKZ805.
     Small Craft Advisory for PKZ806-811-812-816-817-851-854-857-858.
     Gale Warning for PKZ807.
     Small Craft Advisory for PKZ809.
     Brisk Wind Advisory for PKZ810.
     Brisk Wind Advisory for PKZ813-815-861.
     Brisk Wind Advisory for PKZ814.
     Small Craft Advisory for PKZ850-853.
     Gale Warning for PKZ856.
     Brisk Wind Advisory for PKZ859-860.

&&

$$

Ahsenmacher