Area Forecast Discussion
Issued by NWS Anchorage, AK

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000
FXAK68 PAFC 141309
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
509 AM AKDT Tue May 14 2019

.ANALYSIS AND UPPER LEVELS...Quiet weather continues as the large
scale weather pattern is moving quite slowly, almost stagnant.
Upper level troughing continues to exist extending from the Bering
then SE into the Gulf of Alaska. It is anchored by a low pressure
system there. Weak ridging exists over the Aleutians. This
translates to the surface with not much change in weather. Weak
high pressure still exists over Southcentral AK, while low
pressure spins in the southern Gulf of AK. Some smaller
circulations can be seen on satellite in the Bering Sea as well.
Isolated showers are also present in the Gulf of AK and SW AK.

&&

.MODEL DISCUSSION...Models are continuing to handle this quiet
weather pattern well. Thus, forecast confidence remains high for
the next few days. One difference to note between models is
placement and amount of precipitation along the Southcentral
Coast late Wednesday. A blend of models was used for a solution
tonight, leaning towards the NAM to resolve this issue.

&&

.AVIATION...
PANC...VFR conditions and light winds will persist. A light sea
breeze is possible this afternoon and is reflected in the TAF.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3...Tue
through Thu)...
The area remains caught between an upper level trough over
Bristol Bay and a sharp ridge over NW Canada. The net effect
continues to be a slow trend towards slightly warmer and drier
conditions for most areas, but still an abundance of mid and upper
level clouds. For today, just about all areas should stay dry (to
include Kodiak) with the exception of a few stray showers, mainly
along the mountains in the afternoon. The ridge will have the
most influence over the eastern half of Southcentral AK (east of
Eureka) where temperatures will climb into the mid-upper 60s with
a fair amount of sunshine.

By Wednesday, the ridge will move to the north and open the door
for a broad North Pacific Low to start to influence the area. For
most population centers, this will just mean an increase in
southeast winds and clouds. However, for coastal locations and
Kodiak, expect steady rain to settle in through the day. Over the
Copper River Basin, instability will be on the rise within a
developing thermal trough. This coupled with a subtle influx of
moisture could result in a few thunderstorms developing over the
higher terrain during peak heating.

For Thursday, the North Pacific Low will dominate the synoptic
pattern. This will leave the area open to multiple waves of energy
embedded in easterly flow. At the surface, the thermal trough
will continue to gain strength, primarily over the Copper River
Basin north through the AK Range. Thunderstorms will once again be
possible in these areas Thu afternoon and evening.

&&

.FIRE WEATHER...
The Copper River Basin will see another day of warming and drying
today. RH values should start to trend up slightly Wed as high
pressure moves north of the area. However, with an intensifying
coastal ridge and inland thermal trough, gusty southeast winds are
looking more likely to develop Wed afternoon. These winds
combined with temperatures in the mid 60s and relatively low RH
values could approach critical thresholds. We will continue to
monitor this possibility closely.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3)...
The low over the Kuskokwim Delta will slowly push north through
today before changing direction and tracking south on Wednesday
making it past the Alaska Peninsula Thursday. This setup will
result in light winds and showers for southwest Alaska through
Thursday. With daytime heating in a convective environment, the
afternoon hours will see more shower activity than the overnight
hours.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3)...
An upper level low over the eastern Bering will bring showers to
areas around the eastern Bering including the eastern Aleutians
and Alaska Peninsula. Showers will continue through Thursday as
the low tracks south and eventually moves into the North Pacific.
Out west, a North Pacific low will approach the central and
western Aleutians bringing small craft level easterly winds to
the waters around the islands tonight through Wednesday. Wednesday
night the low will track off to the south which will diminish the
winds and shift them to the north.

&&

.MARINE (Days 3 through 5)...
For Thursday through Saturday in the Gulf, a series of lows will
cross the area from east to west. Winds and seas are expected to
be fairly low, but small craft advisory conditions area possible
with these systems if they area stronger than currently shown in
the models.

For the Bering Sea and Aleutians, generally northerly winds are
expected with high pressure to the west and low pressure to the
east. Some small craft advisory winds and seas are possible over
the eastern Bering from the Kuskokwim Delta south through the
Pribilofs to the eastern Aleutians.

&&

.LONG TERM FORECAST (Days 3 through 7)...
The general pattern for the extended portion of the forecast will
consist of a low over the Gulf with a trough extending northwest
into the eastern Bering, and a ridge over northwest Canada
extending into central and northern Alaska. Much of the
uncertainty exists in just how the various low centers and troughs
rotate around the the main low, with a series of weak easterly
waves pushing across the Gulf into southern Alaska. The weather
conditions over southern Alaska will consist of showery periods
due to the proximity of the low, with the timing difficult to
discern. Precipitation chances are fairly low. Temperatures will
generally be a bit above normal.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...BJB
SOUTHCENTRAL ALASKA...MSO
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK
MARINE/LONG TERM...BL



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