873
FXAK69 PAFG 042116
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
116 PM AKDT Thu Jul 4 2024

.SYNOPSIS...
The cooler and wetter pattern persists through the weekend as a
series of fronts push across northern Alaska. Most of northern
Alaska will see between half an inch and an inch of rain through
Sunday night, with locally higher amounts; the exceptions being
the Yukon Flats to Arctic Village which will see a quarter of an
inch or less, the far southern Y-K Delta and portions of the Upper
Tanana Valley, which will see less than a quarter of an inch.
Southwest winds increase across the Interior once again Friday
with the strongest winds occurring over Interior summits along the
Steese Highway east of Twelve Mile Summit, where a Wind Advisory
has been issued for gusts to 45 mph.

&&

.DISCUSSION...
Synoptic Analysis and Forecast...
Aloft, at 500 mb, a 529 dam (decameter) low is centered over the
western Canadian Archipelago, with a shortwave stretching west
over the Arctic waters. This low tracks westward to be centered
400 NM north of Kaktovik Friday afternoon, dropping south to be
centered 200 NM north of Nuiqsut Saturday afternoon, and then
heads east to be 150 NM north of Prudhoe Bay. As the low tracks
westward, the shortwave will drop south and east across the Arctic
Coast through Friday, with a second shortwave tracking east
across the Arctic Coast Saturday and Sunday. Meanwhile, a 546 dam
low offshore northeast Kamchatka lifts northeast to be centered in
the Gulf of Anadyr by Friday afternoon and then weakens as it
moves to Kotzebue Sound by Saturday morning. This low gets
absorbed by the low over the Arctic waters Saturday, resulting in
broad troughing across much of mainland Alaska.

At the surface, a 993 mb low is over Victoria Island with a front
extending west over the offshore Arctic Waters, a developing 998
mb low is over Prince Patrick Island, a 1005 mb low is 50 NM south
of Demarcation Point, and a 1002 mb low is 175 NM northwest of
Point Hope. As the the low over Victoria Island tracks off to the
east Friday and Saturday, the 998 mb low over Prince Patrick
Island will weaken as it moves to be 350 NM N of Kaktovik Friday
afternoon at 1002 mb, to 200 NM north of Prudhoe Bay at 1004 mb
Saturday morning, and continue to weaken. The low 50 NM south of
Demarcation Point weakens through Saturday. The low northwest of
Point Hope this afternoon moves to Point Hope by Saturday morning
as a 1000 mb low and then weakens as a front pushes across the
Chukchi Sea Coast and West Coast Friday night and a 1002 mb low
develops over the northwestern Brooks Range. This low deepens to
998 mb as it moves to Demarcation Point Saturday afternoon,
dragging the front across the western Brooks Range, Seward
Peninsula, and northwestern Interior by Saturday afternoon. The
front continues eastward Sunday across the eastern Brooks Range
and Interior, as a 1008 mb low develops near Arctic Village Sunday
morning.

Models...
The 04/12Z models initialize fairly well against the 12Z RAOBS but
were 10 to 20 meters too weak with weak ridge axis extending out
of the North Pacific and into Anchorage. Models are in good
agreement with the overall synoptic pattern through the weekend.
There continue to be differences in QPF amounts through the
weekend. All models bring in significant wetting rains to northern
Alaska, but vary in amounts. Opted to lean towards a blend to
account for the differences and come to a middle ground. Leaned
towards the NAM and NAM Nest to capture the stronger winds across
the Interior Summits and the stronger southerly gap winds
developing in the Alaska Range passes.

North Slope and Brooks Range...
A cool and wet couple of days is in store for the North Slope and
Brooks Range as a series of fronts move across the region. West
winds will shift to the north northeast along the coast Friday and
across the Arctic Plains, while winds in the Brooks Range largely
remain out of the southwest 10 to 20 mph and gusty through
Friday. A northerly surge Saturday evening and night will shift
winds in the Brooks Range to the north. Rain and shower activity
picks up this evening and tonight, increasing greatly on Friday
and Saturday. Rainfall totals of half an inch to an inch are
expected through Sunday night, with up to 2 inches possible in the
Brooks Range. Heading into Saturday, especially the afternoon and
evening, temperatures will be dropping off pretty significantly
with high temperatures in the 30s to near 40 along the coast.
There is a chance for a rain/snow mix, or a complete changeover to
snow west of Deadhorse. Given the rain beforehand, accumulations
are not likely at this point.

West Coast and Western Interior...
Not a lot of change through the weekend for the West Coast and
Western Interior as a series of fronts impact the area. Rain and
shower activity backs off a bit for St Lawrence Island and from the
Seward Peninsula south tonight and Friday morning before the next
round of precip moves in, while showers and rain continue across
the Chukchi Sea coast, southwestern Brooks Range, and Western
Interior. Most of the area will see between half an inch and an
inch of rain through Sunday night, with up to two inches over the
south slopes of the Western Brooks Range. The far southern Y-K
Delta will see a quarter of an inch or less. Gusty southwest winds
of 10 to 20 mph persist through at least Saturday, with winds to
25 mph in the higher terrain. High temperatures largely in the mid
50s to lower 60s across inland areas, and in the mid 40s to mid
50s along the coast, coolest temperatures further north.
Temperatures cool a degree or two Saturday.

Central and Eastern Interior...
A series of fronts moving across the area will maintain cooler and
wetter conditions through the weekend. Temperatures top out in
the mid 50s to mid 60s Saturday and Sunday. Much of the area will
see between half an inch and an inch of rain through Sunday night,
though the Yukon Flats to Arctic Village and areas south of
Chicken to the Upper Tanana Valley will see lighter accumulations,
generally a quarter of an inch or less. Gusty southwesterly winds
persist this afternoon, with the strongest winds occurring in the
higher terrain of the Interior. Winds strengthen late
tonight/early Friday across the central and eastern Interior
summits, especially those in the White Mountains and along the
Steese Highway, east of Twelve Mile Summit, where wind gusts to 45
mph are anticipated Friday and a Wind Advisory has been issued.
Southerly flow strengthens in the Alaska Range passes Friday into
Saturday, with gusts of 35 to 45 mph expected, potentially hitting
50 mph in the eastern Alaska Range. The eastern Alaska Range
passes will have to be closely monitored for Wind Advisory
potential.

Extended Forecast Days 4-7...The rainy and cooler pattern will
continue into next week as upper level troughing remains the
dominant feature. By the end of next week temperatures moderate,
especially over the eastern half of the state as an upper level
low in the Gulf brings southerly flow aloft.

Coastal Hazard Potential Days 3 and 4...As southwest winds
persist, expect water levels to remain about 0.5-2 feet above the
normal high tide line this weekend from Nome south. The highest
water levels are expected at Koyuk with 4 to 5 feet of rise in
water levels through the weekend. Residents with items on the
beach should continue to take precautions as water levels remain
high until the beginning of next week.

&&

.FIRE WEATHER...
Cooler and wetter will remain the rule this weekend as a series of
fronts push across northern Alaska. Wetting rains expected for
much of the area, with half an inch to an inch of rain being
common across the vast majority of the Interior;the exceptions
being the Yukon Flats to Arctic Village which will see a quarter
of an inch or less, the far southern Y-K Delta and portions of the
Upper Tanana Valley, which will see less than a quarter of an
inch. Gusty southwesterly winds persist this afternoon, with the
strongest winds occurring in the higher terrain of the Interior.
Winds strengthen late tonight/early Friday across the central and
eastern Interior summits, especially those in the White Mountains
and along the Steese Highway, east of Twelve Mile Summit, where
wind gusts to 45 mph are anticipated Friday. Not to be left out,
southerly flow strengthens in the Alaska Range passes Friday into
Saturday, with gusts of 35 to 45 mph expected, potentially hitting
50 mph in the eastern Alaska Range.

&&

.HYDROLOGY...
Heavy rainfall will continue from the Brooks Range south along the
West Coast, with some areas south of the Brooks Range seeing an
additional 1.5 to 2.5 inches of rainfall through the weekend.
Expect significant rises on rivers draining the Brooks Range,
including, but not limited to, the Wulik, Kobuk, Noatak, and
Koyukuk Rivers and smaller creeks and streams.

In the Interior, rain is going to be moving through each day
through the weekend as well with rainfall amounts upwards of
1 to 2 inches. The highest amounts should be expected in the higher
terrain. This may also lead to rises in some rivers and streams.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Wind Advisory for AKZ834.
PK...Small Craft Advisory for PKZ802-803-851>854.
     Small Craft Advisory for PKZ804.
     Small Craft Advisory for PKZ805.
     Small Craft Advisory for PKZ806.
     Small Craft Advisory for PKZ807-856.
     Small Craft Advisory for PKZ811.
     Small Craft Advisory for PKZ816.
     Small Craft Advisory for PKZ817.
     Small Craft Advisory for PKZ850.
&&

$$