889
FXAK68 PAFC 061311
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
511 AM AKDT Mon May 6 2024

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

Composite radar, satellite imagery, and surface observations
early this morning indicate that much of the precipitation has
moved out of the Copper River Valley with main precipitation axis
extending from the southern Kenai Peninsula to the Mat-Su Valley
and Talkeetna Mountains. This main swath of precipitation will
gradually push westwards this morning with precipitation lingering
across the Susitna Valley and western Kenai Peninsula through
this afternoon. As expected, the Copper Basin and Mat Valley saw
the bulk of the precipitation from this wave with Gulkana and
Palmer receiving almost three-quarters of an inch of rainfall over
the past 12-24 hrs. Elsewhere, including Wasilla down to the
Anchorage Bowl, a quarter to half an inch of rainfall were common.

The large area of low pressure remains out across the northern Gulf
today, but will quickly weaken by tonight as it opens and lifts
inland. This shortwave will provide enough lift to get another round
of showers to develop near the Wrangells before they push northward.
Otherwise, generally quiet weather today with just some isolated to
scattered showers for most of Southcentral.

While the aforementioned Gulf low will move out tonight, another low
will quickly lift into the Gulf from the north Pacific on Tuesday.
As the associated front lifts across the Gulf, precipitation will
spread northward along the front. Models tend to be in good
agreement with the bulk of the precipitation impacting Southeast
Alaska, but will see enhanced showers develop along the northern
Gulf coastal areas, Prince William Sound, and the eastern Kenai
Peninsula through Wednesday night.

- PP

&&


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

Light, scattered rain and snow showers will continue through mid-
week. Conditions favorable for freezing spray accumulation will
be heaviest just south of the ice edge from west of Nunivak Island
northward through this afternoon. An Arctic High over Eastern
Russia and a low over Western Alaska are funneling arctic air
south through the Bering Strait today. The coldest air is
expected across the Pribilof Islands, coastal areas of the
Kuskokwim Delta to the Alaska Peninsula, and along the Bristol Bay
coast. Persistent onshore winds will keep temperatures below
normal under mostly cloudy skies. Persistent onshore winds will
keep tonight and tomorrow`s temperatures below normal under a
mostly cloudy sky. Tuesday morning, a weak low pressure drops
south from the Bering Strait, bringing a reinforcing push of cold
air southward to the Alaska Peninsula and Aleutians by the evening
hours. This low will move into Bristol Bay by Wednesday night.
Thursday morning a Kamchatka low moves into the Bering Sea along a
path just north of the Aleutian Chain, resulting in heavier snow
and rain showers for areas west of Dutch Harbor.


&&
.LONG TERM FORECAST (Days 4 through 7: Thursday through Sunday)...

Broad troughing stretches from the western Aleutians towards the
Gulf of Alaska, with multiple surface lows tracking across the
Aleutians and into the Gulf. Precipitation along coastal regions
of Southcentral, including Kodiak Island, will persist through
much of the long term. Some precipitation will likely spill over
into Southwest Alaska as the Gulf low moves over the Kenai
Peninsula on Thursday. Since the low developing out near the
Western Aleutians on Thursday stays south of the Aleutians as it
travels towards the Gulf, precipitation will likely diminish over
Southwest by late Friday. An upper-level ridge attempts to build
through the weekend across portions of the Bering and Aleutians,
however, each model solution shows differences in the way the
ridge interacts with the surrounding lows/troughs.

&&

.AVIATION...

PANC...Southeasterly winds out of Turnagain Arm are expected to
see a slight lull by mid-morning before picking back up this
afternoon and continuing until Tuesday morning. Lingering showers
moving over the terminal are possible this morning but will
likely diminish into the afternoon. During periods of showers,
ceilings and visibility may drop near MVFR levels and may go MVFR
for a time. However, southeasterly Turnagain Arm winds may limit
the persistence of the MVFR periods, favoring VFR conditions.

&&


$$