141
FXAK69 PAFG 032124
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
124 PM AKDT Mon Jun 3 2024

.SYNOPSIS...
An active pattern persists today with a couple of new stories. A
Red Flag Warning has been issued for the Yukon Delta beginning at
2 PM this afternoon for warm, dry and windy conditions. Easterly
waves will continue to move through the Interior with scattered
showers and thunderstorms this week. Wednesday is looking like one
of the largest lightning days of the year in the Interior with
widespread wetting rains possible as well. The West Coast will be
chilly and windy today with isolated snow showers possible from
the NW Arctic Coast to St. Lawrence Island. The strongest winds
will be near Kivalina where there is a High Wind Warning through
noon tomorrow. Along the North Slope and Brooks Range, expect
areas of light snow, as well as some freezing drizzle and light
freezing rain tonight.

&&

.DISCUSSION...

Upper Level Analysis...
A 529 decameter upper low is dropping south over the Seward
Peninsula providing northerly flow over the coast and
east/southeast flow for much of the rest of the state. The main
driver for the Interior weather has been a low in the Gulf of
Alaska providing easterly flow with several shortwaves. This will
continue and we currently have one of those waves located in the
SE Interior. This will push northwest through the Central Interior
this afternoon and evening. Tomorrow the main 500mb shortwave has
lagged behind a little bit, but there is plenty of 700mb vorticity
that will push through the Central and Eastern Interior with
scattered showers and storms. Wednesday afternoon currently has
the strongest shortwave moving across the state with numerous
vorticity maximums and plenty of upper level support for storms.

Surface Analysis...
A strong thermal trough is in place over the Interior with a high
over the Chukchi creating a strong pressure gradient over the West
Coast resulting in very strong wind. A surface convergence zone
remains in place from Anaktuvuk Pass to Bethel. Showers and storms
will develop along that line today. Light snow and potentially
freezing drizzle or freezing rain will continue at times along the
North Slope. Then, there is a quick cut-off where Red Flag
conditions are likely in and around Fort Yukon. Otherwise, partly
to mostly cloudy skies prevail in the Interior with showers and
storms developing this afternoon as a shortwave moves through.

Central and Eastern Interior..
Showers and storms will be the game today for most of the
Interior. The one exception will be around Fort Yukon where warm,
dry and windy conditions are expected today and tomorrow during
the day. Overnight, red flag conditions end as temperatures and
winds drop as well as relative humidity rises. Otherwise cloudy
skies may limit some convection today but some clearing is
developing from Dry Creek east which will assist convective
initiation. Tomorrow will be a "rinse and repeat" type of day
with comparable temperatures and afternoon showers/storms.
Wednesday looks like it could be one of the largest days for
thunderstorms in the Interior so far. Some guidance is beginning
to show Mixed Layer CAPE values near 500-1000 J/kg with a strong
shortwave which would promote scattered to numerous thunderstorms.
Luckily, these storms look to be wet and come with wetting rains
for much of the Interior. Some spots may see as much as 0.50-1.00"
of rain, especially in the most persistent thunderstorms. This
still remains a couple of days out so things can change, but the
potential for widespread thunderstorms in the Interior is there.
Thursday looks to clear out a bit with less thunderstorm activity
and temperatures in the 60s to near 70.

West Coast and Western Interior...
Windy and chilly for the remainder of the afternoon today with a
High Wind Warning for Kivalina through noon tomorrow. A few snow
showers will be around the Bering Strait through Wednesday
afternoon. Temperatures away from the Strait will be gradually
warming up Tuesday through Thursday as winds diminish.

North Slope and Brooks Range...
The North Slope remains relatively active with light snow and
light freezing rain or drizzle around tonight and tomorrow. As
temperatures warm into the 60s and low 70s along the southern
Brooks Range tomorrow, a few showers and storms will develop
which may move through the North Slope during the
afternoon/evening hours. These would mostly turn into rain showers
as they move through the Plains and Arctic Coast. Wednesday looks
to dry out with some clearing possible as well. A warming trend
then continues through the end of the week.

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

&&

.FIRE WEATHER...
A Red Flag Warning will begin at 2 PM this afternoon in the Yukon
Flats and continue through 9 PM tomorrow evening. Sustained winds
around Hodzana and Graphite Lake have been around 15 mph with
gusts up to 30 mph. Minimum RHs are expected to be around 20-25%
with temperatures in the mid to upper 70s today. Tomorrow, wind
will be a bit more marginal around 10 to 15 with gusts to 25 mph
in the afternoon and evening, RHs will be as low as 25% and
temperatures will be in the upper 70s. Tonight and tomorrow night,
winds come down, temperatures drop and RHs will rebound.
Otherwise, in terms of precipitation, scattered showers and
isolated storms will be around today and tomorrow with the bulk of
activity remaining over the higher terrain. Fort Yukon will have a
chance for widely scattered storms this evening as an easterly
wave moves through.

Wednesday looks like it could be a big lightning day, potentially
the largest one of the year so far. Already, guidance is hinting
at 500-1000 J/kg of CAPE with the NAM being bullish and showing up
to 1500 J/kg in the Middle Tanana Valley. A strong shortwave is
looking to move through during the afternoon and it will spark
thunderstorms. There is a potential for widespread storms with
frequent lightning. Luckily, these storms do look to be wet and
come with heavy rain. Some localized spots may receive up to
1.00" of rain in the most persistent thunderstorms. We will be
determining where exactly the thunderstorms set up, but it is
beginning to look focused from Stevens Village south. The
shortwave will then push west during the evening with
thunderstorms possible as far northwest as Ambler Wednesday
evening.

&&

.HYDROLOGY...
Warming temperatures along the North Slope this week will promote
snowmelt and the potential for high water for the Sag, Colville
and Kuparuk Rivers and their tributaries. The Colville has a few
ice jams on it already which may result in some flooding concerns.
One ice jam of note is a known seven mile long ice jam downstream
of Ocean Point (on the Colville) and a smaller ice jam a few
miles long at Horseshoe Bend (roughly 9 river miles up from
Nuiqsut). Snowmelt will likely push out these ice jams, but expect
high water upstream before the release. Water levels are expected
to crest by the end of this week into the weekend.

The water level in Fort Yukon will continue receding very slowly.
Satellites and ground observations continue to indicate abundant
snow in the Porcupine Mountains. As temperatures warm this week,
snowmelt could lead to continued high water along the Porcupine
and the interrelated sloughs.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...High Wind Warning for AKZ815.
     Red Flag Warning for AKZ933.
PK...Gale Warning for PKZ801-850.
     Gale Warning for PKZ802-853.
     Small Craft Advisory for PKZ803.
     Small Craft Advisory for PKZ805.
     Gale Warning for PKZ806-810-854-856.
     Gale Warning for PKZ807.
     Brisk Wind Advisory for PKZ808-855.
     Brisk Wind Advisory for PKZ809.
     Gale Warning for PKZ811.
     Small Craft Advisory for PKZ812-816-817-851-857-858.
     Heavy Freezing Spray Warning for PKZ817.
     Small Craft Advisory for PKZ852.
&&

$$

Bianco