Gale Warning 603, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
439 PM AKST Sun Nov 3 2019

.ANALYSIS AND UPPER LEVELS...

There is an upper level ridge that extends from just off the west
coast of North America into the central Gulf of Alaska with an
upper level low well south of the Aleutians. The jet stream is
running south of this low and then turns sharply to the Alaska
Peninsula where it then accelerates as it moves from west-to-east
across Southwest and Southcentral Alaska. This pattern continues
to bring warm air into southern Alaska and the front that is in
the western Gulf and moving into the Bristol Bay region is a warm
front which will keep most of Southern Alaska in unseasonably warm
conditions.

&&

.MODEL DISCUSSION...
Models are doing well overall the next few days. There is a
period in the middle of the week where there is a noticeable
disparity with their solutions with the low in the eastern Bering
Sea. This looks to be due to the way a small upper level low near
the Gulf of Anadyr on Monday rides down the eastern side of the
main Bering Sea ridge and merges with the upper level low
approaching from the North Pacific. In spite of this, the main
features hold together and therefore this model discrepancy is
likely just an issue for the eastern Bering Sea region and not
something that is likely to cause major shifts in thinking over
the entire area.

&&

.AVIATION...
PANC...Stratus will be the main concern around the airport tonight
through Monday morning. With the mid-level clouds increasing over
the area, development of fog over the airport looks less likely
and this appears to be more of a low stratus situation.

&&

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

Skies will partially clear overnight, with offshore flow
continuing into Monday morning. However fog remains somewhat
uncertain, dependent on how much high cloud cover persists over
the region. In any case, it remains a possibility, particularly
in low-lying areas.

High pressure over the Brooks Range will track southeastward into
the Yukon Territory on Monday. This will both inhibit the
northward progression of a front in the Gulf and increase
northeasterly winds in gaps in the terrain including Thompson
Pass, Broad Pass and the Matanuska Valley. These winds are
expected to be strongest Monday evening into Tuesday. Winds will
diminish Tuesday as the pressure gradient weakens. This in turn
will allow the front and associated precipitation to move onshore
and thus rain is likely across coastal areas of Prince William
Sound and the eastern Kenai. Anchorage and the Mat-Su are expected
to remain dry in downsloped cross-barrier flow, while the front
will remain south of the Copper River Basin.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1-3)...

A warm front, associated with a North Pacific low, lifting north
into Southwest Alaska will cause some complications in
precipitation type for the next few days. As the front moves
across the AKPEN and interior Bristol Bay, the main precipitation
type should initially be rain this evening. There is the potential
for freezing rain Monday afternoon through early Tuesday morning,
which would stay north of Dillingham. There could be a brief
period of freezing rain for Dillingham, but temperatures look like
they will remain above freezing as this front brings in warmer
air, resulting in rain. Therefore, no products have been issued
at this time for the Bristol Bay region, but we will continue to
keep an eye on this overnight.

Looking farther north across the Kuskokwim Delta and Valley, there
is higher confidence that there will be freezing rain starting on
Monday evening. Colder temperatures already in place across the
Kuskokwim Delta and Valley will allow for a longer duration of
freezing rain to stay around the area. A Winter Storm Watch has
been issued for the Kuskokwim Delta, which could see ice
accumulations of two tenths to four tenths of an inch from Monday
evening through Tuesday evening. As it gets closer to this event,
it is likely that an Ice Storm Warning will be issued. Across the
Kuskokwim Valley, freezing rain is expected during this time as
well. A Winter Weather Advisory will likely be issued tomorrow
for mixed precipitation (freezing rain/snow). By Wednesday, the
front begins to weaken, leaving a showery (mostly rainy) pattern
across the region.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...

Small craft advisory winds will continue across the eastern
Aleutians and Bering as a North Pacific low continues to lift
northward through Monday. Northerly flow over the central and
eastern Bering could lead to gale force winds out of bays and
passed along the Aleutian Chain Monday afternoon through evening.
A gale force front will briefly pass over the western Aleutians
and Bering starting Monday afternoon, which will quickly lift
north out of the region Tuesday night.

&&

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

Localized gale force winds are possible through Bristol Bay
and across the Barren Islands and Shelikof Strait on Wednesday,
all on easterly winds. No gales are expected on Thursday. On
Friday, a gale force front may cross into the western Aleutians,
but there is significant model disagreement on the timing of that
feature and the gales may hold off until Saturday.

&&

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

The long-term forecast is mostly uncertain with a lot of model
disagreement for much of the period. On Wednesday, a low over the
southern Bering somewhere between the Pribilofs and Dutch Harbor
will keep the weather warm and unstable from the Gulf over to
Southwest Alaska, and for much of the southern Bering. The low
will weaken and remain nearly stationary in the same area on
Thursday. The weather remains showery and unstable across both
Southwest Alaska and Southcentral on Thursday. By Friday, there is
significant model uncertainty regarding a strong trough of cold
air over the Yukon while ridging and warm air persist over western
Alaska.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale Warning 127 130 138 172 178.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...EZ
SOUTHCENTRAL ALASKA...AP
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...AH
MARINE/LONG TERM...JW