521
FXAK68 PAFC 251316
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
516 AM AKDT Sat May 25 2024

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

Warmer and drier conditions are on deck for southcentral Alaska. An
area of low pressure in the Gulf of Alaska will continue shifting
southward today, resulting in precipitation gradually diminishing
north to south. Breaks in cloud cover in conjunction with warmer
boundary layer temps will result in surface temperatures warming
into the upper 50s to lower 60s for most of lower elevation areas.
These warmer conditions will yield some modest instability...
resulting in showers developing across the Copper River Basin,
Talkeetnas, and perhaps the Mat-Su Valley. An isolated lightning
strike or two from a particularly strong shower cannot be ruled out.
Southwesterly storm motion combined with upper-level support from a
shortwave dropping south across the Alaska Range may allow for some
rain showers to push into Anchorage and the western Kenai late
Saturday evening into the overnight hours.

Then, an upper-level low dropping from south of the North Slope
will interact with the low lingering over the Gulf and one or more
easterly shortwaves tracking in from Yukon. This produces a
fairly uncertain forecast for Sunday and beyond, though the
combination of features will provide support for rain showers and
likely some steadier rainfall at times nudging into the
easternmost portions of the forecast area as early as Saturday
night. These precipitation features will propagate generally east
to west, with the most likely areas to see over a tenth of an inch
of rainfall in the Copper River Basin. However, there is moderate
potential for this heavier rain to reach the western half of
Southcentral late Sunday and heading into next week. Regardless,
expect continued generally cool and cloudy weather with the
occasional break of sun as well as the occasional shower.

-Brown/Quesada

&&


.SHORT TERM FORECAST SOUTHWEST ALASKA, THE BERING SEA AND THE
ALEUTIANS (Days 1 through 3)...

An elongated trough remains over the Bering this morning with an
upper low, currently stretched from Bristol Bay into Kodiak
Island, to exit southwest Alaska and move into the northern Gulf
through this afternoon. Ultimately, this will see what had been
persistent shower activity over Southwest come to an end. Later
this afternoon a shortwave trough moves from the Seward Peninsula
into the Western Alaska Range and Alaska Peninsula. With shower
activity expected to gradually clear throughout the day, models
are hinting at least some instability developing. Wet thunderstorm
potential will not be zero as a result. MUCAPE of roughly 300
J/kg and total/totals of ranging from 40 to 50 are present on the
NAM across the eastern Kuskokwim Delta, coincident with the
passage of the aforementioned shortwave trough. Thus, a isolated
wet thunderstorms may be possible in the late afternoon and early
evening hours. Coverage of any thunderstorm activity should be
limited, with activity propagating southwestward along the western
side of the Kuskokwim Mountains through the evening hours.

With the departure of the upper low over Southwest, weak
northerly flow will become more prominent over both Southwest and
the Bering the next couple of days. Sunday sees the arrival of a
front into the Western and Central Aleutians, which will signal an
increase in showers over the western half of the Aleutian Chain.
The front weakens late Monday as it reaches the Eastern Aleutians,
but scattered shower activity will likely persist for portions of
the southern Bering. New shortwave activity along the front may
reinvigorate winds and showers as the front moves into Southwest
Alaska Tuesday morning


-BL

&&


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

The long term begins Tuesday with weak deformation and troughing
remaining over Southcentral and a transient ridge moving from the
AKPen and eastern Aleutians toward Southwest Alaska. The weak
troughing over Southcentral will lend to continued shower activity
across the region, mainly across the mountains and interior
portions of Southcentral. The ridge continues east for Wednesday,
helping bring a temporary reprieve to the extensive cloud cover
and shower activity. However, the ridge quickly moves to the
Alaska Panhandle as the upper-level trough, anchored by an upper-
level low and associated surface low, reestablishes itself over
the eastern Bering and Aleutians by late Wednesday. The result
will be a return to widespread cloud cover and precipitation
moving from the AKPen Wednesday afternoon across almost all of
the Southern Mainland through Thursday. The broad long-wave trough
remains in place with continued unsettled weather and cooler
temperatures through the end of the week and into the start of
next weekend.

- TM

&&


.AVIATION...

PANC...High MVFR to VFR conditions will persist throughout the
TAF period. Ceilings could remain at or below the 5000 ft
threshold for much of the morning, but this deck will likely
scatter/lift out by the afternoon. A short period of southeast
winds is again possible as winds bend into the terminal from the
Turnagain Arm, but the duration and intensity will likely be
weaker compared to yesterday.

&&


$$