Gale Warning 578, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
451 AM AKST Sun Nov 10 2019

.ANALYSIS AND UPPER LEVELS...

The very slow moving pattern we have in place means little change
in the weather from the past couple days, so there is not much to
update in the AFD. High pressure continues to cover most of the
mainland and Gulf of Alaska. Patchy stratus and fog continues to
remain trapped under the high. Disorganized low pressure is in
the Bering Sea, though not much is happening with it since it is
pretty weak.

&&

.MODEL DISCUSSION...

Models continue to be in good agreement in the short term.
Precipitation type in Southwest AK remains the only challenge.
Forecast confidence is above average.

&&

.AVIATION...
PANC...VFR conditions and light winds will persist. Guidance
indicates IFR ceilings for the airfield tonight, so added that to
the last line of the TAF. Will take another look at this later
this morning.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...

A weak upper level wave and associated surface trough will move
north across Southcentral today and then weakens as it heads into
the interior tonight. It will mainly bring increased chances of
rain to the Kenai Peninsula, especially over southern and eastern
coasts, and chances of light snow over the Susitna Valley. Most
other areas will experience increased cloud cover and low
probability precipitation. A general drying trend is expected
again tonight as the upper ridge rebuilds and offshore flow and
gap winds strengthen. These conditions are expected to continue
through Monday. Patchy fog is possible in sheltered areas. A
strong front moving slowly north over the Gulf brings easterly
gales to offshore waters this evening through Monday.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...

With high pressure to the east and low pressure to the west,
southerly flow is expected aloft for southwest Alaska through
Monday. At the surface, the pressure gradient will help keep cold
offshore flow. This setup will allow for the possibility of
freezing rain for areas around southwest Alaska through Monday.
However, precipitation is expected to be light and intermittent.
Any that does fall will primarily be either rain or snow which
will limit the chance of any significant freezing rain. More than
likely any freezing rain will be localized and short lived.

&&

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

A triple point low is forming along a frontal boundary that
stretches through the western Bering and across the central
Aleutians. The low is forming near the central Aleutians and will
then track to the northeast pushing rain east across the eastern
Aleutians, Pribilof Islands and Alaska Peninsula through tonight.
On Monday the low will track into the northern Bering and weaken.
Cold air will move in behind the low bringing a mix of light rain
and snow to the western Aleutians through Monday. Monday night a
North Pacific low will approach the eastern Aleutians with its
front bringing rain to the islands.

&&

.MARINE (Days 3 through 5)...

Beginning the extended marine forecast on Tuesday evening,
attention will be focused on a storm force low over the North
Pacific, with the strong gale force front moving as far north as
the Eastern Aleutians and southeast Bering Sea This low will
remain in place and weaken through Wednesday. Thereafter, a
wintery pattern will develop over the Bering as the first strong
push of arctic air develops a widespread area of strong offshore
gale force winds centered over the eastern Bering Sea and Bering
Strait. This pattern will likely last through the end of the work
week as the storm track then shifts into the Gulf of Alaska. This
looks to be a rather stormy pattern for the Gulf of Alaska toward
the end of the period Thu-Sat with a series of lows/fronts moving
toward the Gulf Coast as a strong Pacific jet pattern develops.

&&

.LONG TERM FORECAST (Days 3 through 7)...

Beginning the extended period forecast on Tuesday, there will be a
storm force low over the North Pacific with a gale force low
impacting the Eastern Aleutians. Farther north, a strong arctic
trough will be digging south across the Brooks Range. In between,
the mainland of Alaska will be sandwiched in between weak high
pressure which will help to keep the southern Mainland dry. By
Wednesday, the pattern will switch to a much more stormy pattern
as the deep storm force low eventually surges a warm front into
the Gulf of Alaska, with another barrage of wet and warm weather
for Southcentral as the arctic trough digs into the Bering Sea.
This stormy pattern looks to last through the work week as the
North Pacific firehose jet pattern establishes itself. With a
closer proximity to the arctic air, Southwest Alaska may see
better chances for snow as the warm fronts roll into the Gulf of
Alaska and assault Southcentral with continued warm anomalies.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALES: 170 173 175 351 352 413.
FIRE WEATHER...NONE.

&&

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