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000
FXAK68 PAFC 242348
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
348 PM AKDT Tue May 24 2022

.ANALYSIS AND UPPER LEVELS...

The pattern aloft is a very typical high latitude weak-flow
situation. While the main branch of the subtropical jet stream is
well to the south (impacting the lower 48), there are two main
features aloft controlling our short term weather over the Great
Land. A broad, weak, multi-centered trough stretches from the
Canadian Yukon southward through the Gulf of Alaska into the
northern Pacific Ocean. The other is a closed ridge over the
western Bering Sea. Between those two is some weak enhancement of
northerly winds and a shearing out disturbance responsisble for
Monday`s thunderstorms over Southwest Alaska.

In terms of sensible weather, there remains considerable
cloudiness left over from showers/thunderstorms as well as the
disturbance in the Gulf, forming a thin mid-level cloud deck
across most of Southcentral. Weak rain showers exist from the
northern Gulf through the Copper River Basin, as well as the
southwest mainland.

&&

.MODEL DISCUSSION...

Guidance has a good handle on the large scale synoptics over the
next few days. Generally they feature the ridge over the Bering
Sea strengthening and impinging on the mainland for the weekend.
Any differences in the models are small scale instability/shower
placement on the terrain. Confidence is higher than normal.

&&

.AVIATION...

PANC...VFR conditions and light winds will persist.

&&

.FIRE WEATHER...

Looking later in the week and toward the weekend, it appears as if
conditions are going to return toward hotter and drier. An upper
level ridge building over the southwest mainland from the Pacific
will bring a drying northerly flow and the warmest air mass of the
year so far. At this time winds don`t look like they will reach
red flag conditions, but it`s too soon to say. Temperatures look
to reach into the 70s for much of Southcentral with RH values in
the teens/20s.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3;
Tonight through Saturday afternoon)...

An upper-level ridge builds in from the west as a shortwave trough
shears apart over the Copper River Basin. Rain showers associated
with the trough will taper off overnight tonight across the
Copper River Basin and Prince William Sound area. Meanwhile, the
high pressure ridge will continue expanding from west to east
across Southcentral through Saturday. As a result, expect dry and
hot conditions to prevail across much of the region for this
weekend. Winds are expected to stay light, with diurnal sea
breezes for coastal locations.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: This
afternoon through Friday)...

The last in a series of shortwaves is moving across Southwest
Alaska this afternoon and evening producing showers and isolated
thunderstorms. CAPE will approach 500 J/kg and Total Totals in
the lower 50s will combine with surface heating and an upper
level shortwave to produce isolated thunderstorms mainly near the
higher terrain of the Kuskokwim Mountains and western Alaskan
Range and portions of the Kuskokwim Valley near Kalskag and Aniak.
Currently thunderstorms have fired near Kalskag and Aniak along
an area of low level convergence and should continue to fire near
this area and drift southward as the storm motion is from the
north. These storms could move into southern portions of the
Kilbuck Mountains approaching coastal locations near Togiak and
westward towards Goodnews Bay. As the shortwave moves south
tonight showers will linger across the area and gradually diminish
by Wednesday morning as high pressure builds in from the west. No
fog expected tonight or tomorrow morning as cloud cover and the
shortwave energy will keep the area a bit too unstable for fog
formation. By Wednesday afternoon most of the area will become
mostly sunny and drier as the high pushes into Southwest Alaska.
Patchy fog is possible across the Kuskokwim Delta Thursday morning
due to light onshore flow. As we head into Thursday and Friday
the high will stall across western Alaska which will create hot
and dry conditions especially on Friday as highs will be in the
mid to upper 70s across the Kuskokwim Valley as well as portions
of Bristol Bay. The Kuskokwim Delta will stay a bit cooler with
highs in the upper 60s to low 70s.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3: This
afternoon through Friday)...

High pressure continues to dominate most of the Bering with a
couple of weak lows producing periods of showers across the
Aleutian Chain. Stratus and areas of fog are expected across the
central Bering and across the Pribilofs through most of the short
term forecast period. A weak surface trough stretches across
parts of the eastern Bering with a few showers possible. A frontal
system will approach the western and central Aleutians Wednesday
and Thursday with small craft winds likely as well as light rain.
Otherwise high pressure will dominate the rest of the area through
Friday, with the exception of the AKPen and eastern Aleutians that
will experience showers Thursday and Friday as an upper level
shortwave moves across that area.

&&.

MARINE (Days 3 through 5/Friday through Sunday)...

Gulf of Alaska - High pressure lingers across the Southern Gulf
through Sunday. A weak trough remains over the North Gulf Coast
through Sunday. Forecast confidence is good. Gusty westerly winds
extend from the Alaska Peninsula along Southeastern Kodiak Island
into the central Gulf through Sunday. Seas less than 10 feet.

Aleutians / Bering - The Bering high moves northward through
Sunday. A Kamchatka low and front tracks over the Western
Aleutians and Bering for Sunday. Forecast confidence is fair due
to the speeds of movement of the low and front. Gusty Northerly
winds continue over the Eastern Bering through Sunday. Gusty
Southeasterly winds ahead of the Western Bering low. Seas less
than 10 feet.

&&

.LONG TERM FORECAST (Days 4 through 7/Saturday through Tuesday)...

A key feature in the long term that models have consistently
hinted at is a broad upper level ridge in place over the mainland
while an upper level trough extends from Kamchatka southward into
the north Pacific. There are some notable differences between
model solutions. Currently the EC solution maintains more of a
blocking ridge over the mainland through the weekend, while the
GFS and Canadian solutions both advertise the ridge weakening and
moving eastward over the Alaska-Yukon border earlier in time than
the EC. Sunday night, the GFS holds steady on a weak upper level
low lifting inland from the Gulf. This feature has the potential
to introduce showers, but confidence remains low as no other model
has locked onto this feature. By Monday, there is consensus that
a North Pacific low will lift into the Gulf and move inland over
Southcentral. This low will likely introduce a pattern change,
bringing cloudy, wet weather to the southern half of the state,
including Southcentral, the Alaska Peninsula, and the Copper River
Basin, for the start of the next workweek.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Flood Advisory: 141.
MARINE...NONE.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...ML
SOUTHCENTRAL ALASKA...AF
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...RC
MARINE/LONG TERM...KZ/KO