084
FXAK69 PAFG 100010
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
410 PM AKDT Thu May 9 2024

.SYNOPSIS...
Shower chances will persist over the next several days. A
combination of rain and snow showers are expected over the Yukon
Delta, Seward Peninsula, and areas along the Arctic Coast.
Locations farther inland and at lower elevations can expect mainly
rain showers. There is a small chance of thunderstorms over
portions of the Interior both north and south of the White
Mountains through this evening. Storm chances for Friday will push
a little farther north, primarily over the Yukon Flats.

Strong southerly winds aloft will translate to strong southerly
gap winds of 15 to 30 mph with gusts to 45 mph expected near Delta
Junction and the eastern Alaska Range Friday night and Saturday
morning.

&&

.DISCUSSION...
Model Analysis...
12Z deterministic models appear to have initialized better than
the 00Z set. At 500mb GFS, NAM, and ECMWF were still 2 dam
(decameter) too low over northwest Alaska compared to the 12Z
radiosonde flights and matched up well with the upper-level low
over the eastern Aleutians. Inverted trough arced from the
eastern Aleutian upper low over the Bering Sea west of the Yukon
Delta to to northeast Russia. A trough of low pressure, remnant of
an filling upper low, jutted northward over the Seward Peninsula
into northwest Alaska. Lobes of vorticity were noted near
Utqiagvik and over the Alaskan Panhandle which will continue to
propagate cyclonically around the state, which will lead to
enhanced forcing for ascent.

At the surface at 12Z, several areas of low pressure were
identified. A broad area of low pressure stretched from near
Norton Sound eastward across the Interior. Satellite imagery
revealed several focused circulations near Galena, Rampart, and
near Fort Greely. Expect those areas of low pressure to slowly
strengthen today and rotate cyclonically north and eastward. Look
for enhanced shower potential and a few thunderstorms this
afternoon.

Today through Saturday...

Diurnal showers and a few thunderstorms will continue to
percolate through this evening over the Interior. Mixed layer CAPE
values a high as 100-150 J/kg is forecast from the north slope of
the Alaska Range as far north as the White Mountains and Yukon
Flats. Hodographs over that area are straight in the lowest 3 km
with around 30-35 knots of 0-3km shear. Tall skinny CAPE profile
in conjunction with falling heights aloft should be sufficient for
a few thunderstorms. A heavy shower passed over our office a few
hours ago and produced very small hail. Expect a few of the
stronger cells to be capable of small hail in addition to a few
lightning strikes. As sun angle lowers later this evening,
instability will diminish and showers will gradually weaken.

Portions of Northwest Alaska, generally south of Utqiagvik to
Nome and Unalakleet will be under the northern lobe of vorticity
and should continue to see overcast skies and light snow. Snow
accumulations of 1 to 4 inches are expected. In the wake of the
upper trough from Utqiagvik east along the Arctic Coast have seen
forcing for ascent and clearing skies. Lower snow totals are
expected over the Yukon Delta as temperatures will trend warmer. A
few spots may pick up an inch or two, particularly in the higher
elevation areas.

The broad upper level pattern will continue to see cyclonic flow
aloft. The light snow over Northwest Alaska will push out over the
Chukchi Sea and the Bering Straight. Diurnal showers are forecast
again for the Interior Friday. A few thunderstorms are forecast
again, although the focus will be farther north, generally north
of the White Mountains and across the Yukon Flats. South of the
White Mountains, isolated to scattered showers are expected.

Another surge of stronger winds aloft will arrive over the Alaska
Range Friday afternoon and evening which will generate gap flow
through the passes. The strongest winds will be found from
Isabell Pass to Fort Greely and Delta Junction where winds of 15
to 30 mph and gusts to 45 mph are forecast Friday night into
Saturday morning. An upper-level trough will accompany those
stronger winds and will arrive over the eastern Interior and the
ALCAN border Saturday afternoon. Another day of showers and
perhaps a few thunderstorms are forecast for the Yukon Flats.

Extended Forecast Days 4-7...
Model guidance continues to indicate persistent broad upper level
troughing over most of the forecast area throughout the extended
forecast period. Periodic intrusions of ridging from Canada into
the eastern Interior are also suggested. This pattern will
continue to support scattered.. showers across much of northern
Alaska. Model solutions gradually disperse Sunday and beyond,
suggesting lower than average overall confidence in the forecast
beyond Day 3 Saturday.

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

.FIRE WEATHER...
High temperatures in the 50s to near 60 through Friday. Scattered
to numerous showers this evening throughout the Interior as a
disturbance moves through the region tonight. Slight chance of
thunderstorms this afternoon and early this evening over the
Fairbanks area and the Yukon Flats north of the White Mountains.
The thunderstorm threat will shift north for Friday with areas in
the Yukon Flats seeing the greatest potential for storms, around 5
to 10 percent. Isolated to scattered showers will remain
throughout the weekend as more disturbances move through the area.
Southerly gap winds of 15 to 30 mph with gusts to 45 mph are
forecast Friday night and Saturday morning from Isabell Pass to
Delta Junction areas. Near-critical fire weather conditions are
possible with RH values of 35 to 25 mph.

&&

.HYDROLOGY...
The breakup front on the Yukon river is approaching Circle and
expected to reach Circle in the near future. As of 7 pm Wednesday,
an ice jam was in place 12 miles upriver from Circle with some
overbank flooding of low areas with no water over higher banks.
Downstream of Circle, small sloughs and streams are clearing of
ice, but the main channel of the Yukon still has ice in-place.

The Tanana and Upper Kuskokwim River are mostly open.

Rivers north of the Yukon River have mostly intact ice.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Flood Watch for AKZ833.
PK...Heavy Freezing Spray Warning for PKZ806.
&&

$$

Huyck