182
FXAK69 PAFG 112211
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
211 PM AKDT Tue Jun 11 2024

.SYNOPSIS...
Continued regime with isolated thunderstorms over the S Interior,
with heavier rainfall over the Alaska Range. Some thunderstorms
North winds over the Bering Strait will switch to south on Thu,
and this will also bring in much cooler temps out west. Slow
warming trend begins over the Interior Friday as a ridge builds
in.

&&

.DISCUSSION...

Upper Levels and Analysis...
There is a strong 570 dam closed blocking high over the Chukchi
Sea. There are a pair of undercutting shortwave troughs moving
west at the base of this trough, with one over the Chukotsk, and
the other over the Noatak Valley. A remnant thermal trough
persists over the S Interior, with the main low center over the
Tanana Valley. There is a weak shortwave trough over the
Fortymile, slowly moving southwest.

Model Discussion...
Models are in good agreement with the larger scale pattern. They
are overall in better agreement with the convective pattern as
well, the next few days. The GFS and ECMWF were favored with the
NAM nest for winds, and the hi-res models for precip.

Central and Eastern Interior...
Heavy rain showers with some strong thunderstorms will develop
late this afternoon and continue into the overnight over the E and
SE Interior into the Alaska Range. It`ll be dry north of the White
Mtns, so this will mainly be a S Interior threat. Storms may
produce small hail with heavy downpours, as the amount of
instability is moderate. There is a concern for fairly heavy
rainfall over the Alaska Range, which may cause issues on smaller
streams. We will be issuing a Special Weather Statement with this
forecast package with more details with that.

Showers with more thunderstorms are likely on Wed, although
instability will be a bit less on Wednesday. Slowly, ridging
builds in Thu with general drying weather. Friday will be warmer
with chances for thunderstorms, especially over the E Interior,
where instability parameters look best, with the possibility of a
shortwave trough dropping south over the E periphery of the ridge
axis.

West Coast and Western Interior...
Isolated thunderstorms this afternoon and evening will be possible
across the Interior and into the Seward Peninsula today. By Wed
isolated thunder chances will be over the Interior and into the W
Brooks Range. A low with cooler air will be moving into the West
Coast with winds switching around to west-southwest Thu and Fri,
which will quickly reduce temps back to more seasonal normal
levels.

North Slope and Brooks Range...
Northeast winds and high pressure over the Arctic continues, with more
stratus for the Arctic E of Point Lay and up to the slopes of the
Brooks Range. There is very little change in weather the next few
days, with persistent 15 to 30 mph northeast winds, strongest
over the W Arctic.

Extended Forecast Days 4-7...
A moderate strength ridge will be building into the E Interior
this weekend and into the next week, which will promote warmer
temps and more chances for thunderstorms over most of the
Interior. Meanwhile, a strong arctic low will be meandering over
the NW Arctic, which will bring in west winds to the West Coast
and cooler temps to the western half of the Mainland.

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

&&

.FIRE WEATHER...
The thermal trough remains over the S Interior and into the
Western Interior to Seward Peninsula this evening. This will
promote areas of widely scattered thunderstorms, and given the
instability, some storms will be strong and may produce a fair
amount of lightning activity. However, these will continue to be
very wet, with a high likelihood of heavy wetting rains from about
Salcha east to the headwaters of the Tanana Valley, with heavy
rains possible through Wed night. Storms will be more isolated
after today as the thermal trough weakens. It will remain drier
north of the thermal trough across the Yukon Flats. Wed and Thu
will be near red flag criteria, with min RH in the low 20s and
highs near the mid 70s, but winds look to be around 6 to 11 mph
and just below criteria.

We are monitoring the chance for very high based thunderstorms
over the E Interior on Friday, as a ridge aloft builds in and
a disturbance passes over the E side of this ridge. Overall
though, a warming trend is expected over the eastern half of the
Interior this weekend, while it cools out west.

&&

.HYDROLOGY...
High water from snowmelt will make its way down rivers on the
Central North Slope over the next several days, and minor flooding
remains possible. Water levels will remain high through at least
Thursday, then fall slowly through the weekend. The high water
caused by warm temperatures and snow melt in the Brooks Range. It
is expected that high water will remain through at least Thursday,
and that water levels will fall slowly through the weekend. Water
levels will fall more significantly next week as temperatures
cool in the Brooks Range.

The Sagavanirktok River near Pump Station 3 crested on Saturday,
but remains high today. That high water is expected to reach the
coast today and to remain high for several days. Water will be
near bankfull, with minor flooding possible in low lying areas
downstream of Pump Station 3 over the next several days. Water
levels are expected fall slowly late this, then fall more next
week.

The Colville River at Umiat crested Monday and remains high on
Tuesday. That high water will reach the coast Today and Wednesday
and remain high for several days. Minor flooding of low lying
areas along the Colville River downstream of Nuiqsut is possible.

On the Kuparuk River at the Bridge, flooding is occuring. The
low-water crossings approaching the bridges are inundated with
water, with up to 8 inches of water over the road. Water will
remain high through Thursday, and then is expected to fall slowly
through the weekend.

Heavy showers over the next two days will result in the potential
for 1 to 3 inches of rainfall across parts of the Alaska Range,
which will likely result in fast stream rises and overall rises
along all rivers draining the Alaska Range. Some storms will be
strong and will drop copious rainfall in a short period of time.
Residents should be aware of the possibility of rapid stream
rises with heavy rainfalls generally lasting into Wednesday
evening.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...None.
PK...Small Craft Advisory for PKZ811.
     Small Craft Advisory for PKZ812-858.
     Brisk Wind Advisory for PKZ814-815.
     Small Craft Advisory for PKZ857.
     Brisk Wind Advisory for PKZ859.
&&

$$

Ahsenmacher
Hydro: Brader