080
FXAK69 PAFG 211051
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
251 AM AKDT Tue May 21 2024

.SYNOPSIS...
A Bering Sea front is moving inland across the West Coast tonight,
and this will shift northeast today. Alaska Range gap winds will
increase as well and will peak late this afternoon and evening,
but it should become breezy across most of the Interior today with
that chinook flow. Temperatures remain above seasonal norms for
the Interior into Wednesday, then things cool down with chances
for rainfall on Thursday. Break-up continues over the Yukon Delta
and Lower Yukon, and breaking is beginning over parts of the N
Slope, as well. Snowmelt flooding will be a concern over the Yukon
Flats along the Porcupine River in the coming days.

&&

.DISCUSSION...

Upper Levels and Analysis...
There is a 522 dam mobile low over the Bering Sea with a leading
shortwave trough/front moving into the YK Delta this morning in
the form of widespread rain/rain showers. There is a shortwave
ridge aloft over the E Interior, with heights around 555 dam.
There is a departing mobile shortwave trough over the BC region of
Canada, with heights around 540 dam. There is a 991 mb low over
the Bering Sea and a 1029 mb high over the arctic waters. There is
a weak thermal trough over the S Interior.

Model Discussion...
Models are in very good agreement with the general pattern but
they continue to struggle with the way the Bering low transitions
into the Gulf of Alaska, which will then have a significant
influence on the precipitation pattern over the Interior Wed night
and Thu. Overall, the models all show something semi-similar but
all different, so we will just favor a continued blend at this
time, which continues the theme of cooler by Thu with increased
chances for rain showers. Prior to that, we favored the hi-res
winds and we also increased winds today over the Interior due to
the chinook flow.

Central and Eastern Interior...
Another nice day today, with increased southerly winds and temps
pushing up to near or slightly above 70 once again. Gap winds in
the AK Range will peak today and this evening with gusts to near
50 mph then trend down Wednesday evening. Heavy rain showers will
develop Wed evening and into Thursday, but there is very low
confidence where those will occur, and right now, the best bet is
likely over the higher elevations, with less chances over the
lower elevation valleys. Showers persist into Friday along with
cooler temps from the recent string of above average readings.

West Coast and Western Interior...
A front with widespread rain/rain showers and easterly winds is
moving inland across the YK Delta and shifts across the Seward
Peninsula and Interior through tonight. Rain showers behind this
front will rotate in from the Bering Sea and will persist into
Wednesday. Another front brings more rain to the SW Coast and
Lower Yukon Thu night and Fri. Three day total rainfall amounts
will be rather light, with around 0.5 inches on the lower Yukon to
0.25 inches or less further north.

North Slope and Brooks Range...
Stratus, fog, periodic snow showers and east winds will dominate
for the next several days. Wind gusts to gale force will develop over
the W Arctic from Point Lay to Point Hope later today into early
Wednesday. There is a chance that snow showers may turn to mixed
precip after today as warmer air aloft moves in, with spotty ice
pellets or possibly freezing drizzle. The crest of the Brooks
Range will see increased chances for rain (snow above 2500 feet by
Wed night) showers midweek and beyond as an arctic front stalls
over the mountains.

Extended Forecast Days 4-7...
A progressive Bering sea flow continues in the extended period as
yet another Bering front is moving inland across SW AK early
Friday. This low takes the exact same path as the last and will
dive into the Gulf of AK and bring showers to the Interior. After
Monday, it looks fairly blase weather-wise with minimal
significant impacts, and no significant anomalies to note as the
Mainland finds itself sandwiched between several weak upper level
lows.

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

&&

.FIRE WEATHER...
No changes to thinking with a minor chinook pattern today, but
strong enough to push AK Range gap winds to 30+ mph, which will
support red flag conditions down by Delta Junction. However, it
will be generally dry and breezy everywhere this afternoon in the
Interior with widespread min RH values in the teens and low 20s.
And with temps in the low 70s, it will be near critical weather
conditions across most of the E Interior and Tanana Valley today.

Wednesday the chinook is waning and temps come down, along with
weaker winds. Rain shower chances increase Thu with cooler temps
into Fri. Right now, no thunderstorm chances are anticipated,
although there is a less than 5 percent chance on Thu along the
ALCAN.

&&

.HYDROLOGY...

Lower Yukon break-up continues as running ice and high water
remain at St Mary`s, Pitkas Point and Mountain Village and a ice
jam flood watch remains for those areas through Tue. The break up
front is now downstream of Mountain Village and will likely get to
the Yukon Delta at Alakanuk, Emmonak, Nunam Iqua and Kotlik
sometime between late tonight and Fri, bringing the risk of ice
jam flooding to those areas tonight through Fri. Flood watches
are out for all these areas.

The water levels along the Porcupine River at the Border rose to
record levels over the weekend due to heavy snowmelt. This high
water is expected to reach Ft Yukon on Wed, where it will
gradually fills sloughs and swales east of Ft Yukon and eventually
bring high water into Ft Yukon late this week with high water
continuing into next week. A flood watch is valid front this Wed
through next week Wed.

There are no new reports about the Buckland River, but there was a
reported ice jam downstream of Buckland a couple days ago with
rising water levels. We will continue to monitor.

Rivers on the North Slope are beginning to flow with water
flowing over ice with some open water areas. Those area will
continue to see increasing melt this week.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Flood Watch for AKZ825.
     Flood Watch for AKZ826.
     Flood Watch for AKZ833.
     Red Flag Warning for AKZ937.
PK...Small Craft Advisory for PKZ803.
     Small Craft Advisory for PKZ804-805-807.
     Brisk Wind Advisory for PKZ806.
     Brisk Wind Advisory for PKZ810.
     Small Craft Advisory for PKZ811.
     Small Craft Advisory for PKZ812.
     Brisk Wind Advisory for PKZ814.
     Brisk Wind Advisory for PKZ815.
     Small Craft Advisory for PKZ816.
     Small Craft Advisory for PKZ817.
     Small Craft Advisory for PKZ850.
     Small Craft Advisory for PKZ851.
     Small Craft Advisory for PKZ852.
     Brisk Wind Advisory for PKZ853.
     Small Craft Advisory for PKZ854.
     Brisk Wind Advisory for PKZ856.
     Brisk Wind Advisory for PKZ857-858.
     Brisk Wind Advisory for PKZ860-861.
&&

$$

Ahsenmacher