Area Forecast Discussion
Issued by NWS Anchorage, AK

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000
FXAK68 PAFC 160014
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
414 PM AKDT Wed Aug 15 2018


.ANALYSIS AND UPPER LEVELS...
A trough spans across Alaska this afternoon with a closed low
centered over the eastern Bering near the Kuskokwim Delta.
Scattered showers are developing along weak boundaries across the
southern mainland. West of this low, another front is situated
along the west and central Aleutians and is the next stronger
system to watch for as it stays on an easterly track through the
end of this week.

&&

.MODEL DISCUSSION... Models are in rather good agreement through the
first 48 hours. This is leading to moderate to high forecast
confidence regarding synoptic features, however pinpointing showers
across Southcentral and SW AK will remain tricky. Models are
struggling somewhat with fog across SW AK Thu morning, so used some
hand edits to incorporate that weather element. The low moving up
from the N Pacific Fri PM starts to cause some problems among the
members. There are some differences in timing associated with it and
strength on current runs ranges from 994 mb to 979 mb. Either way,
it does looks like it will be the next big weather maker as we head
towards the weekend.
&&

.AVIATION...
PANC...VFR conditions prevails through Thursday night, however
showers are possible through this time from low pressure moving a
front to the coast tonight. The front remains stationary along
the coast through Thursday while slowly diminishing. Light winds
may vary a bit as the surface gradient weakens as low pressure
sags southwest.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2...Thu and
Fri)... Scattered shower will continue to develop through Thursday
as low pressure remains the dominant synoptic force over the
southern mainland. The main low center pushes a front across
Kodiak this evening and then swings it northeast to the coast
overnight. Only a few hundredths of new accumulation is expected
as the front quickly washes out as the low center is pulled
southeast and is absorbed into the next approaching storm system.
Friday will be the warmest and driest day of the week across the
region; however, this is only a brief break as the next storm
system moves to Kodiak Island by late Friday morning.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2...Thu and
Fri)... A vertically stacked low will remain in place over the
Eastern Bering keeping the weather cool and unsettled for the next
couple of days. The low is readily visible just off the coast of
Cape Newenham. It will keep showers going through much of SW AK,
especially along the coast and the Aleutian Range, this evening.
The parent low will drift south towards Cold Bay on Thu. While
this should allow for a slight drying trend for most of SW AK,
there will still be a chance for some light showers throughout
Bristol Bay. Wind will be generally light across the area which
could lead to some patchy fog to start the day Thu.

For Fri, some weak, induced ridging will try to slide in from the
north. This could bring a better chance for fog Fri morning. The
day should generally be dry with the exception of a stray shower
along the higher terrain and the Bristol Bay coastline. A
developing N Pacific low will approach the area from south to
north late Fri. This will bring an increase in E to SE winds
across the area overnight into Sat. These winds will initially
provide some lee-side drying (downsloping) before rain moves back
into Bristol Bay Sat.


&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2...Thu and
Fri)...
The domain will be split by 2 separate weather systems. First is a
rather tight, vertically stacked low over the Eastern Bering. The
other is an elongating front over the Western Aleutians. The first
low will bring sub-small craft level winds and showers with it as
it drifts towards Cold Bay through Thu. The front along the
Western Aleutians will bring steady rain and small-craft
southeasterly winds through Thu morning. The front will weaken as
it stretches towards the Central Aleutians.

By Fri, the front will drift south of the chain and absorb the
previously mentioned low. This will leave the area rather quiet to
start the day. Attention will then shift to a developing N Pacific
low. This system looks to move towards Sand Point bringing gale-
force sustained winds with storm-force gusts. It will also have a
deep sub-tropical moisture fetch associated with it allowing for
another round of moderate-heavy rain across the Eastern Aleutians
and Alaska Peninsula.

&&

.LONG TERM FORECAST (Days 3 through 7)...
The long term beginning Friday night starts with a North Pacific
low sandwiched between two ridges. The first ridge will be over
the eastern Gulf while the other is over the central Bering. There
is some discrepancy between the models on the exact position of
the low and subsequently its front, but the general consensus is
that the front will bring rain to the Alaska Peninsula and Kodiak
Island Friday night. Through the weekend the system will slowly
track north spreading rain to the southern mainland with the
heaviest amounts along the north Gulf coast and Alaska Peninsula.

Meanwhile out west, another system will push into the Bering over
the weekend as the central Bering ridge breaks down. Early next
week the upper level low centers of the two main lows look to
merge into a broad area of low pressure over the Bering with
ridging off to the east. This setup would keep a rainy pattern
for the region into mid next week.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...None.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...KH/MO
SOUTHCENTRAL ALASKA...KH
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MO
LONG TERM...DK


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