Gale Warning 222, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
414 AM AKDT Sun Mar 31 2019

.ANALYSIS AND UPPER LEVELS...
High pressure continues to dominate the southern mainland keeping
skies clear of most cloud cover and light winds over the area. Out
west, an upper level low is approaching the Alaska Peninsula from
the south bringing showers to the area. Farther west still, a
trough sits over the central and western Aleutians bringing rain
to the islands.

&&

.MODEL DISCUSSION...
Model agreement remains high through early next week regarding the
persistent high over the mainland. In addition, model solutions
are consistent regarding a short wave progression from the North
Pacific into the Bering on Monday.

&&

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

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
The strong upper level high, currently centered over Mainland
Alaska will shift slowly to the southeast through Monday before
weakening to a flat ridge over the Gulf through Tuesday. A rather
flat pressure gradient over the area today bringing light general
winds, will allow for the development of localized sea breezes in
the afternoon. Troughing will develop along the northern Gulf
coast tonight, shifting winds to light offshore. Weak offshore
flow will persist Monday and then gradually increase Tuesday.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3/Sunday
through Tuesday)...

High pressure and fair weather will persist across Southwest
Alaska through Tuesday. The warm high pressure over the area will
mean the well above normal temperatures will continue, with highs
between 45 and 55 all across the area for the next several days.
There is a slight chance of a shower or two immediately along the
coast on Monday, but that's the only chance of any weather
occurring with this strong high pressure in place.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3/Sunday
through Tuesday).

Quiet weather persists in the eastern Bering and Aleutians due to
high pressure. A stalled out front is over the western Aleutians
and Bering west of Atka. This will continue the light rain and
gusty winds across those areas. The front will finally dissipate
Sunday night. A pair of North Pacific lows will then approach the
area. These lows will begin to merge on Monday into a large low
along the Aleutians by Monday night. This will result in widespread
small craft to gale conditions and continued southeasterly winds
over nearly all of the Bering through this time. Rain will
overspread much of the southern Bering as well, including all of
the Aleutians Monday night. Firmly entrenched high pressure to the
east will prevent any of that active weather from impacting the
eastern Bering and the coast.

&&

.MARINE (Days 3 through 5/Tuesday through Thursday)...

Gulf of Alaska...Confidence remains high for benign conditions
in the Gulf of Alaska waters through Wednesday. Forecast
confidence drops by Thursday as the pattern begins to shift and
become more active in the Gulf. Right now it looks favorable
for winds will remain small craft or lower.

Bering Sea/Aleutians...There is uncertainty in the track of
storms just south of the Aleutian chain. However, this is largely
a continuation of current weather, so would expect periods of gale
force winds as each storm passes by.

&&

.LONG TERM FORECAST (Days 4 through 7/Wednesday through Saturday)...

The long-term period begins on Wednesday with an upper level ridge
centered from Southwest Alaska up to the Russian Arctic, dividing
the flow across Alaska. On the east side of the ridge a short-wave
trough will drop down the eastern half of mainland Alaska, with
arctic air spreading southward. Model guidance diverges on the
ultimate destination of this trough, with some stalling the trough
in the vicinity of Southcentral/the northern Gulf and others
rotating it westward as ridging over Southwest Alaska retreats
northward. The upper level jet associated with the trough is
weak, so do not expect a big bora windstorm. It looks more like a
harmless incursion of colder air into Southcentral - and possibly
into Southwest Alaska. Expect temperatures for Thursday through
Saturday to return to closer to normal, with high temperatures in
the upper 30s to lower 40s rather than the widespread upper 40s to
around 50 currently being observed. The precipitation forecast is
much more difficult because of the dependency on the evolution of
the trough. If it digs far enough south into the Gulf, could see
a weak surface low spin up and bring precipitation onshore to
Southcentral. Southwest Alaska is more likely to remain dry
through the forecast period.

Meanwhile, west of the upper ridge weather will remain active,
with deep storms over the Pacific impacting the Aleutian chain.
As has been the case, ridging to the north will keep the primary
storm track fairly far south. Thus, the Aleutians will be along
the northern periphery of these storms and likely won't experience
the worst of the winds or precipitation.

&&

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

&&

SYNOPSIS AND MODEL DISCUSSION...DK
SOUTHCENTRAL ALASKA...JR
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...BB
MARINE/LONG TERM...SEB