491
FXAK69 PAFG 051110
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
310 AM AKDT Wed Jun 5 2024

.SYNOPSIS...
An impactful day is setting up over the Interior with scattered
thunderstorms developing this afternoon. Some storms could be
strong with frequent lightning, heavy downpours, gusty winds
and hail. Some areas could see rainfall of around 1 inch or
greater. The threat of thunderstorms will continue over the
Interior through Friday.

&&

.DISCUSSION...
Upper Level Analysis... An upper 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.


Central and Eastern Interior...
Wednesday looks like it could be one of the largest days for
thunderstorms in the Interior so far, with models coming into
better agreement. An easterly wave will move across the Interior
enhancing some of the thunderstorms Wednesday afternoon.
The area of thunderstorms expected to develop over the Middle
Tanana Vally in the mid afternoon and continue through the early
evening then push north and west in the evening.

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. Heavy downpours with some
spots expected to receive 0.5 to 1.0" or greater of rainfall,
especially in the most persistent areas of thunderstorms. Frequent
lightning, gusty winds and hail are all possible with strong
thunderstorms and also flash flooding of streets in urban areas.
Thunderstorm potential continues over the Interior Thursday and
Friday but looks slightly less impactful. Temps will remain the
upper 60s to low 70s Wed through Friday.

West Coast and Western Interior...
Temperatures continue to warm with Isolated thunderstorms
extending farther west from Ambler to McGrath. A few of these
storms may come with small hail, gusty winds and briefly heavy
rain. Late Wed evening into Thursday, the shortwave over the
Central Interior will move over the West Coast and Western
Interior, specifically from Galena south and west with areas of
rain, potentially heavy at times. Then by Friday, it looks to dry
out with the exception of a few showers and an isolated storm
towards Ambler.

North Slope and Brooks Range...
Stratus and fog today along the coast with onshore flow
continuing.  Temperatures will be warming as well with highs in
the 30s and 40s north of the Brooks Range, and highs in the 60s
in the Brooks Range. Isolated thunderstorms will be possible in
the Central and Eastern Brooks Range. Friday looks to be quieter,
though a shower or storm is possible in the Western Brooks Range
as the shortwave lifts north. Skies may try to clear along the
North Slope with southerly flow increasing by Friday. Temperatures
will also be warming significantly with highs in the 40s along
the coast.

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

&&

.FIRE WEATHER...
Still warm in the Yukon flats but min RH values slightly higher
in that area, will say still near red flag conditions. Wednesday
looks like it could be a big lightning day, potentially the
largest one of the year so far, with an easterly wave producing
scattered to numerous thunderstorms Wednesday afternoon. 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
producing scattered wet thunderstorms. Locally heavy downpours
with some locations seeing 0.50 to 1 inch of rainfall or greater.
Frequent lighting and gusty winds and hail are all possible. The
area of thunderstorms expected to develop over the Middle Tanana
Vally in the mid afternoon and continue through the early evening
then push north and west in the 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...None.
PK...Gale Warning for PKZ806-807-854-856.
     Small Craft Advisory for PKZ810-816-817-851.
     Small Craft Advisory for PKZ811-857.
     Brisk Wind Advisory for PKZ861.
&&

$$