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FXAK69 PAFG 041158 CCA
AFDAFG

Northern Alaska Forecast Discussion...CORRECTED
National Weather Service Fairbanks AK
358 AM AKDT Tue Jun 4 2024

.SYNOPSIS...
The "kitchen sink" weather pattern will continue to progress
today with minimal changes to the forecast. A Red Flag Warning has
been issued for the Yukon Delta beginning at 2 PM this afternoon
for windy, warm, and dry conditions through the early evening.
Easterly waves will continue through the Interior bringing chances
of showers and thunderstorms, switching to southerly flow in the
lower portions of the Interior by the end of the week. Models are
beginning to come in better agreement for Wednesday being a very
active lightning day with widespread wetting rain across the
Interior. The West Coast will continue to be chilly and breezy
with a deep arctic trough pushing south through the Bering Strait,
bringing snow showers from NW Arctic Coast to St. Lawrence Island
and switching to rain by the end of the week. The North Slope and
Brooks Range will continue to see chances of light snow and
freezing drizzle through Wednesday afternoon, switching over to
chances of light snow.

&&

.DISCUSSION...
Upper Level Analysis... A 529 decameter Arctic low is currently
situated over the Seward Peninsula providing northerly flow over
the West Coast and southerly slow across the Brooks Range into the
North Slope. A 521 decameter low continues to sit in the Gulf of
Alaska being the main driver of east/southeasterly flow, bringing
multiple rounds of shortwaves and vorticity maxes across the
Central and Eastern Interior. The Arctic low will continue to push
south and slightly strengthen, becoming closed off and reaching
the Central parts of the Aleutian Islands early Thursday morning.
The low in the gulf will push westward and merge with the Arctic
low, as it pushes south, switching the majority of the state to an
easterly flow by early Thursday morning. By this point the
southern part of the interior will have shifted to a southerly
flow with a shortwave expected to impact the West Coast late
Thursday night into Friday morning. There is some disagreement
between the models as to when the shortwave will reach the West
Coast, with the GFS being the slowest.

Surface Analysis...
A strong thermal trough remains 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 weak surface low
has formed over the central Interior creating a strong gradient
producing strong winds across the Brooks Range as well. This along
with the convergence zone stretching from Bettles to McGrath is
providing majority of the state with cloud cover and isolated
showers and thunderstorms. Showers will remain likely across this
zone as we move into the overnight hours with another round of
thunderstorms possible South/Central Interior Tuesday afternoon.
Light snow and potentially freezing drizzle or freezing rain will
continue at times along the North Slope today, transitioning to
snow by tonight. Another cut-off will occur over Fort Yukon
Tuesday afternoon where Reg Flag conditions are likely.

Central and Eastern Interior...
Showers and storms will continue to remain persistent, with the
greatest chance of storms occurring during the afternoon and
evening hours during peak heating. However, Fort Yukon, is
expected to be dry and windy on Tuesday with a Red Flag Warning
issued from 2 PM to 9 PM. Wednesday looks like it could be one of
the largest days for thunderstorms in the Interior so far, with
models coming into better agreement. Some guidance is now showing
Mixed Layer CAPE values near 1000-1500 J/kg with the strong
shortwave which would promote scattered to numerous thunderstorms.
Wetting rain remains a possibility with some spots expected to
receive 0.5 to 1.0" of rain, especially in the most persistent
areas of thunderstorms. This trend will continue into Thursday
with fewer thunderstorms possible as the shortwave energy moves
through the area before favorable CAPE and LI indices are able to
form around peak heating. Temperatures are expected to cool down
as well, from the 70s to the low 60s, as we move into Thursday.

West Coast and Western Interior...
Windy and chilly, slightly warmer, expected 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 through Thursday as winds diminish. Another chance of
rain expected Wednesday afternoon into Thursday, with some coastal
and offshore areas likely to get snow showers.

North Slope and Brooks Range...
The North Slope remains relatively active with light snow and
light freezing rain or drizzle around through early Tuesday
morning. 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
continues through the end of the week with another chance of
showers and a potential storm or two along the south side of the
Central and Eastern portions of the Brooks Range Thursday.

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 this evening. The area of main
concern today will be in the north east of Fort Yukon with
sustained winds around 15 mph with gusts up to 25 - 30 mph,
minimum RH values around 20-25%, and temperatures in the mid to
upper 70s.

A weak shortwave is looking to move through during this afternoon
and spark isolated thunderstorms. Some localized spots may
receive up to 0.5 to 1.0" of rain in the most persistent
thunderstorms. Areas east of Venetie and Birch Creek are not
expected to see as much precipitation and will be the area
susceptible to fire ignition. Wednesday looks like it could be a
big lightning day, potentially the largest one of the year so far.
Models coming into better agreement with at 500-1000 J/kg of CAPE
with areas along the Middle Tanana Valley showing up to 1500
J/kg.

&&

.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...Red Flag Warning for AKZ933.
PK...Small Craft Advisory for PKZ801-802.
     Small Craft Advisory for PKZ803-852.
     Small Craft Advisory for PKZ805.
 Gale Warning for PKZ806-810.
 Brisk Wind Advisory for PKZ807.
 Gale Warning for PKZ811.
 Small Craft Advisory for PKZ812.
 Small Craft Advisory for PKZ816-817-850-851-853-857-858.
 Heavy Freezing Spray Warning for PKZ817.
 Gale Warning for PKZ854-856.
 Heavy Freezing Spray Warning for PKZ854.

&&

$$

TWOMBLY