124
FXAK69 PAFG 022126
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
126 PM AKDT Tue Jul 2 2024

.SYNOPSIS...
A strong cold front over the NW Arctic Chukchi coast 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, rain will be moving over a vast majority of them, so
smoke and air quality should improve 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 553 dam upper
low over the western Gulf of AK. There is a 534 dam mobile low
moving east from E Siberia. There is a departing 523 dam arctic
low over the Canadian Archipelago. A subtle shortwave trough is
traversing over the ridge axis across the Yukon Flats and
Fortymile.

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 southwest winds preceding it and behind it. A NAM nest
blend was favored to capture the strong southwest flow 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 will continue over the
Fortymile and parts of the Tanana Valley this afternoon and
eastern Interior, but overall, it`ll be dry with warmer temps
over the S Interior from yesterday, and still warm over the N
Interior. Southwest winds 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.

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 lots of subtropical moisture will bring in
widespread moderate rain to the entire Interior Thursday afternoon
and evening. It looks wet, cool and blustery, quite a change from
last month. Rain will likely continue as on/off showers through
the latter half of Friday. Temperatures are around ten degrees
below seasonal norms by the end of the week for most of the area.
Rainfall totals will be 0.50 to 1.50 inches through Friday.

West Coast and Western Interior...
A strong gale force front will shift inland this 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...
Southwest winds 15 to 30 mph and rainfall with a front 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 Friday into 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. 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 gusting up to 30 knots this afternoon across
the W Interior ahead of a front moving into the NW Arctic. Clouds
over the S Interior will continue this afternoon with some sun
trying to poke through. Any wet isolated thunderstorms look
relegated to the E Interior closer to the ALCAN, with general
showers elsewhere into this evening.

Otherwise, significant fire weather conditions continue into this
evening 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 continue over the northern half of the Interior, as
afternoon temps will be around 75 to 80, and minimum RH in the
upper 20s to near 30 %, thus a red flag warning will continue 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
this 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 with rain,
so minimum RH looks to be higher, into the upper 30s to mid 40s %
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 and this
would be brief though.

.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. Do not think with
recent dry weather though that flooding will be a problem.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Red Flag Warning for AKZ911-932-933.
PK...Small Craft Advisory for PKZ801.
     Small Craft Advisory for PKZ802>806-812-816-817-850>854-857-858.
     Gale Warning for PKZ807-856.
     Small Craft Advisory for PKZ808.
     Small Craft Advisory for PKZ809-855.
     Brisk Wind Advisory for PKZ810.
     Small Craft Advisory for PKZ811.
     Brisk Wind Advisory for PKZ813-859-860.
     Brisk Wind Advisory for PKZ814.
     Brisk Wind Advisory for PKZ815.
     Brisk Wind Advisory for PKZ861.
&&

$$

gjm/jk