Gale Warning 296, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
334 AM AKDT Tue Mar 19 2024

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

An upper level ridge is continuing to build over the southern half
of Southcentral down to the Gulf of Alaska. This ridge will remain
in place through the most of the week with the ridge axis shifting
from near Kodiak Island today to Kayak Island by mid to late week.
The result will be generally quiet weather across Southcentral
with temperatures at or slightly above normal through the week
with only occasional mid and high level clouds moving over the
region.

Subsidence on the east side of the ridge axis has helped dry out
the mid and lower level of the atmosphere following the rain and
snow of Sunday night and Monday morning. As such, widespread fog,
and especially any potential for freezing drizzle, looks to be
less of a concern this morning. There remains the possibility for
fog overnight Tuesday into early Wednesday, especially along Cook
Inlet, as the ridge axis shifts east of this region and a
southwesterly flow and weak moisture advection sets up. Any fog
development, though, will be dependent the eastward extent of high
cloud cover as a weak shortwave moves through Southwest Alaska
and along the Alaska Range Wednesday morning.

Northerly gap winds are expected to increase Wednesday in the wake
of the aforementioned shortwave as a weak coastal trough develops.
While these winds are not expected to be very strong, the winds
may allow for some additional warming that could bring daytime
highs Wednesday to near 50 degrees for locations such as Whittier
and Seward.

-TM

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS
(Days 1 through 3)...

Key Messages:

*Blizzard Warning Remains in Effect for the Kuskokwim Delta
 through 7am this morning. Additional snowfall amounts through 7am
 up to 1 to 2 inches, wind gusts up to 45 mph, and visibility
 reduced to a quarter mile. Conditions will improve through
 morning as snow changes over to rain.

*Elevated southerly winds 35 to 45 mph with gusts up to 60mph will
continue through tonight for the Eastern Bering, highest winds
expected along coastal southwest Alaska and gap-wind prone areas
along the Alaska Peninsula and Eastern Aleutians.

*Otherwise, no major changes to an active forecast period as
multiple storm systems will track across the Aleutian chain and into
the Bering through end week.

Discussion:

A soggy forecast is on tap for much of southwest Alaska out
through the Aleutians as a train of low pressure systems will
bring persistent southerly wind and precipitation to the area.
Strong southerly winds in the North Pacific and Bering Sea will
continue through at Wednesday evening. Gap winds are forecasted to
increase up to 50 to 60 mph in the Eastern Aleutian Islands this
afternoon as an upper level reinforcing wave pushes overhead;
fastest from Dutch Harbor east to Nelson Lagoon and within gap-
wind prone areas. Snow and wind gusts ranging from 30 to 40 mph
that created blizzard conditions from the Kuskokwim Delta through
the night are slowly diminishing as warmer air continues to push
northwards into the area, increasing surface temperatures above
freezing and slowly changing the lingering snow showers to rain.

Looking ahead, across Southwest Alaska, southerly to southwesterly
wind flow is expected to continue through at least mid-week. As for
the the Bering Sea and Aleutians, southerly to southwesterly wind
flow is expected to taper by mid-week, decreasing after Thursday as
an upper level flow goes zonal relative to the Chain. Overall,
temperatures will be above average with highs in the mid 30s to low
40s and lows in the upper 20s to mid 30s.

&&

.LONG TERM FORECAST (Days 4 through 7: Friday through Sunday)...

A highly amplified pattern, featuring deep troughing over the
Bering Sea and Aleutians and a strong ridge across much of
Mainland Alaska and the Gulf remains throughout the period. This
large scale weather pattern will favor above average temperatures
across all of Southern Alaska. While drier weather and mainly calm
conditions are expected for Southcentral Alaska under the ridge,
a warm and stormy pattern is in store for the Bering Sea, Aleutian
Islands, and Southwest Alaska as multiple waves and storms move
through. The biggest challenge in the long term will be honing in
on the track and evolution of these storms, and the timing on when
the ridge begins to break down, allowing for any moisture to make
its way into Southcentral Alaska.

The first major storm complex will be on Friday as models show a
sub-980 mb North Pacific low/low complex moving north and crossing
the Aleutians sometime Friday into Saturday. However, confidence
in the exact details of the low(s) itself still remains low,
leading to high model variability in the location and timing of
the heaviest precipitation and strongest winds. The GFS and
various ensemble members show a single strong, occluding low,
while the EC/Canadian begin to form a low complex with multiple
precipitation and wind maxima.

Forecast confidence continues to decrease by Saturday, with the
question of whether the aforementioned low and troughing is strong
enough to begin to break down the ridge extending across much of
Alaska and the Gulf. Due to the single low, the GFS/GEFS keep the
ridge in place continuing drier and calmer conditions across
Southcentral, while the Canadian/EC and some of their respective
ensembles push a front from the easternmost low eastward, bringing
stronger winds and widespread precipitation into Southcentral.

-ME

&&

.AVIATION...

PANC...VFR conditions and light winds will persist. The potential
for fog development this morning looks less a concern with high
clouds moving over the region and drier air near the surface.
There remains the potential for fog development overnight Tuesday
into Wednesday morning, but again will be dependent on the
extent of mid and high level cloud coverage across the region.

&&

Preliminary Local Storm Report
National Weather Service Anchorage AK
1246 PM AKDT Tue Mar 19 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0623 AM     Non-Tstm Wnd Gst 1 SSE Cold Bay          55.21N 162.73W
03/19/2024  E78 MPH          Aleutians East     AK   Mesonet

&&