827
FXAK68 PAFC 200010
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
410 PM AKDT Sun May 19 2024

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)...

An upper level trough currently located over the Gulf of Alaska
near Prince William Sound will begin moving eastward starting
tonight before departing into Canada. As the low moves eastward, a
few shortwaves will spin around the low back into the northern
parts of the Copper River near the Wrangell Mountains. Widespread
precipitation is expected across the eastern portion of the
forecast area through tomorrow afternoon, with some areas near
Paxson and Mentasta Lake receiving snowfall tonight of around 1-2
inches. Warmer surfaces like roads will struggle to accumulate
snow, but grassier spots could see snow stick to the surface.

For the rest of Southcentral through Tuesday afternoon, weak
ridging will cover the area and allow for a brief period of dryer
weather. Areas of partly cloudy skies over the Kenai Peninsula and
portions of the Mat-Su will also be possible before the next
system impacts the region.

An upper level low in the Bering will continue to move eastward,
with its front moving into Southcentral by Tuesday afternoon.
Widespread heavy rain and pockets of snow near the mountainsides
will pass over the region through at least Wednesday afternoon.
With the ridge just of to the east, a building pressure gradient
over the Chugach and Kenai Mountains will result in stronger
southerly gap winds taking place Tuesday afternoon near the
Kamishak Gap, Turnagain and Kink Arms, and the Copper River Basin.
Southwesterly flow aloft should allow the Anchorage Bowl to get
some rainfall Tuesday afternoon, but a switch in flow to a
southeasterly direction on Wednesday will cause downslope drying
to occur over the area. This next system will result in a brief
cool down over the entire region, but should quickly rebound to
closer to normal temperatures later in the week.

-BS

&&


.SHORT TERM FORECAST SOUTHWEST ALASKA, THE BERING SEA AND THE ALEUTIANS
(Days 1 through 3: This afternoon through Wednesday evening)...

After some fog and low stratus this morning, conditions have
improved for Southwestern Alaska as today progressed. There is
another chance for low stratus and misty conditions Monday
morning, especially for coastal locations of Bristol Bay and the
Kuskokwim Delta. Other than the potential for low stratus, the
first half of Monday is looking quiet across the southwestern
mainland. A Kamchatka low will enter the Bering Sea tonight and
send its front across the Aleutian Chain, to the Alaska Peninsula
(AKPEN), and eventually to the southwestern coastline by Monday
afternoon. There looks to be enough cold air in place for Nunivak
Island and northern portions of the Kuskokwim Delta coast to start
as a period of snow or rain/snow mix mid-day Monday before
changing over to rain in the afternoon and evening. This front,
along with its widespread precipitation, will continue to push
inland to interior Southwest through Tuesday. Moderate to heavy
rain is possible for Bristol Bay Tuesday morning and into the
afternoon. In addition to the heavy precipitation, the pressure
gradient between this front and higher pressure in the Gulf of
Alaska will promote gusty southeasterly Kamishak Gap winds into
interior Bristol Bay for Tuesday.

Colder air will work in behind the front Tuesday morning to the
Kuskokwim Delta where additional shortwaves rotating around the
upper low in the Bering will promote more rain/snow mix there.
This will be same case for the Pribilof Islands as well.
Confidence is low if areas as far west as Bethel will see any
rain/snow mix on Tuesday. The low itself moves to the Kuskokwim
Delta coast Wednesday morning as widespread showers continue
through Wednesday for the southwestern mainland and Bering Sea
side of the AKPEN.

The next system, a stronger North Pacific low, looks lift to the
western Bering and western Aleutian Chain Wednesday. This gale-
force low sends its front eastward to the central Aleutians by
Wednesday evening. Moderate to heavy rain will accompany this
front.

&&

.LONG TERM FORECAST (Days 4 through 7)...

Thursday, an upper-level low centered over the Bering on Thursday
begins to elongate southeastward into the Gulf. Surface
precipitation may start as snow then transition to rain for the
Western Capes, Kuskokwim Delta, and Nunivak Island. A brief ridge
forms before the next upper-level low consolidates and moves
eastward from Attu Island. By Friday the new low has transited the
Bering and continued across Southwest Alaska into the Gulf by
Sunday. The highest rain amounts are expected along the Kenai
Peninsula and the northern Gulf coast. High pressure builds behind
this low across the Bering Saturday and Sunday.

&&

.AVIATION...

PANC...VFR conditions will persist with scattered showers and
ceilings around 4000 ft. Light northerly winds shift to the
southeast for the afternoon/evening as a weak Turnagain Arm wind
develops. Southeasterly winds will diminish through the evening
hours, with ceilings rising above 5000 ft.

-ME

&&


$$