Area Forecast Discussion
Issued by NWS Anchorage, AK

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000
FXAK68 PAFC 311253
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
453 AM AKDT Tue Mar 31 2020

.ANALYSIS AND UPPER LEVELS...

Mainland Alaska is dominated by an upper level high that is
keeping weather rather quiet. A weak surface low southwest of Cold
Bay is bringing some rain to the eastern Aleutians, while the
Alaska Peninsula and coastal southwestern Alaska are seeing a bit
of light snow.

&&

.MODEL DISCUSSION...

Models continue their agreement with the track of a triple point
low bringing it ashore near Cape Newenham Wednesday along with
the front hanging up west of the Alaska and Aleutian Ranges
Wednesday night. Models still in agreement with storm system
tracking across the western Bering on Wednesday. Models agreeing on
an area of precipitation activity setting up in southwest Alaska Thursday
on the northern edge of a persistent upper level ridge over the western
Gulf of Alaska.

&&

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

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
An upper level high over southwest Alaska this morning will move
east into Southcentral today, bringing sunny skies and continued
cool temperatures to the area. The surface gradient has weakened
considerably, and winds will be fairly light. The ridge will stall
over Southcentral tonight through Wednesday night, with the axis
settling in just east of 150 degrees west longitude. This will
open up southwesterly flow aloft, bringing some moisture into the
area. Clouds will increase, and some precipitation is possible
from the ridge axis westward by later Wednesday through Wednesday
night.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Today
through Friday morning)...

A weakening front will continue pushing to the east slowly this
morning with a few snow showers associated with it. Any activity
in the low elevations will dissipate by the mid to late morning
hours with snow showers continuing across the Kilbuck Mountains
into the afternoon hours.

The main story will be a new low forming along this front south
of Cold Bay this morning. This low is expected to track northward
towards Cape Newenham Wednesday morning, then north into the
Kuskokwim Delta and western Alaska. The exact track of this low
will still determine the precipitation types for the Bristol Bay
region for this event. Model guidance has come into better
agreement that this low will track over Cape Newenham, though, any
wobble in the track east will allow for more snowfall to occur in
the Dillingham area with less snow and more mixing or even a
change to rain if the low tracks slightly farther west. The
wobble to the west is looking less likely. Therefore, kept the
forecast leaning towards Dillingham remaining mostly snow for this
event. No changes were made to the snowfall forecast as the low
position still hasn`t really changed from the morning package.
Until this low starts moving northward, the exact track will mean
everything as to the precipitation type and how much downsloping
occurs around Iliamna and King Salmon. It appears that Iliamna and
the Aniak to Sleetmute areas will remain all snow for this event.
King Salmon will have enough warm air push in to change to all
rain Wednesday morning through early Thursday before changing back
to snow as colder air comes back in.

Another low will move northeast towards western Alaska with a
front extending to the south that will bring another round of
precipitation to the region in the form of snow Thursday afternoon
to Friday morning for the Kuskokwim Delta.

&&

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

A dissipating front over the eastern Bering will continue moving
onshore in Southwest Alaska this morning. A low south of Cold Bay
this morning will lift northward to near Cape Newenham Wednesday
morning, then into mainland Alaska. Impacts from this low will
primarily be felt over Southwest Alaska.

A low will move over the northern Bering on Thursday morning,
with some potential for areas of gale force winds across the
waters around Saint Matthew Island. This low will send a front
across the northern Bering and into Southwest Alaska Thursday
afternoon. Behind this front, another surge of cold air is
expected that will bring gusty winds to the northern Bering.

A much stronger front moves into the western Aleutians during the
day on Thursday. Gale force winds and high seas are possible with
this feature, as well as a good push of warm air.

&&

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

Bering Sea and Aleutians...
On Wednesday, there is better model agreement today with the
front entering the northwestern Bering. Winds are forecasted below
gale force at this time, but there will likely be gale force
winds and widespread precipitation accompanying this system that
is showing a stronger signal than yesterday`s model runs. Thus,
confidence is improving in the track and intensity of this low.
Impacts of this in the eastern Bering are minimal as the front is
expected to dissipate before reaching that area through Thursday.

Gulf of Alaska...
There is a chance of small craft southeasterly winds across the
western Gulf on Wednesday associated with a low over Bristol Bay.
Confidence in these small craft winds is low as there are
significant differences in solutions for the low track and
intensity. For Thursday there is low confidence in the wind
forecast, though the weather pattern is expected to remain benign.

&&

.LONG TERM FORECAST (Days 3 through 7/Wednesday through
Sunday)...

Guidance is consistent with an upper level ridge extending across
the Alaskan mainland on Wednesday as an upper trough is present
over the Bering/Aleutians. Due to this, temperatures will be
warmer with a benign weather pattern over the Alaskan mainland and
cooler with a more active weather pattern over the Bering/Aleutians.
Uncertainty increases into Thursday as guidance shows a higher
degree of variation in solutions with upper level synoptic features
which will affect the placement and intensity of surface synoptic
features. The only area of consistency is the upper level ridging
will continue over the eastern Alaskan mainland near the AlCan
border and thus, expect warm temperatures and quiet weather for
that region. Very low forecast confidence exists overall Friday
through Sunday as major differences in upper level synoptic
features exist between guidance which is causing significant
differences in the placement of surface features causing a high
degree of uncertainty in the forecast.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale 178.
         Heavy Freezing Spray 160.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...LTB
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MV
MARINE/LONG TERM...SEB


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