Gale Warning 767, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
451 AM AKST Sun Nov 10 2024

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

A large and mature 966mb low currently centered over the Gulf of
Alaska is now near peak strength, exhibiting a well-defined cyclonic
swirl about 180 nm southeast of Kodiak Island, with pronounced dry
air wrapping into the core, as seen in the GOES West Air Mass RGB
imagery. The system is actively drawing up abundant moisture as
evident by the CIMSS MIMIC Layer Precipitable Water product
showing a tongue of 0.80-1.00" wrapping northward into the Gulf.
This influx of moist air is resulting in widespread precipitation
across the Gulf, with moderate to heavy precipitation for Kodiak
Island and the immediate coastal areas. Observations note about
0.50 to 0.75" of precip has fallen in areas such as Kodiak north
to Chenega, as well as Portage. Farther inland, just enough
residual cold air has allowing precipitation to fall as snow on
the northern end of the precipitation shield, with the AK511
webcams at Turnagain Pass and Summit Lake showing snow overnight
with surface temperatures hovering near the freezing mark. In
fact, the Turnagain Pass SNOTEL located at 1880ft, about 1000ft
above the road, has recorded about 7 inches of snowfall and 7
tenths of liquid equivalent since last evening.

Precipitation will gradually taper off as we progress through the
morning. The low will continue the occlusion process, gradually
weakening through the day as it drifts to the southeast and
farther away from southcentral Alaska. In fact, radar returns
across the Kenai Peninsula have already begun to decrease in
intensity. All in all it should be a rather quiet and otherwise
pleasant day for much of southcentral, with skies clearing from
north to south as the low pulls away.

Monday will be much of the same as the area will remain in a weak
upper-level flow regime. A transient low-amplitude trough axis or
two may pass Monday into Tuesday, but precipitation looks minimal
given lack of moisture. One forecast challenge is that of potential
Cook Inlet / Marine fog and low stratus development as clear skies
and weak-surface winds typically allows this stuff to development,
but with low confidence on the when/where details.

Tuesday will be similar to Monday, though with a slightly deeper
trough axis projected to swing through. Sensible weather impacts
will be minimal, though models are signaling eastern Gulf of Alaska
precipitation will pick up a bit later in the day, but generally
staying out of the forecast area.

Each day through the short term forecast (Sunday through Tuesday)
will be progressively colder as cooler air settles into place. The
temperature and pressure gradients will induce near continuous
outflow gap winds through the period in places such as the Copper
River Delta, out of Resurrection Bay, Passage Canal, and the
Valdez Arm.

-Brown

&&

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

Ridging will start to nudge into the Kuskokwim Delta region from
the Bering Sea and patchy fog and or low stratus will be possible
this morning. Potential for patchy fog may return Monday morning
as well as the ridge strengthens overhead. Expect cool overnight
temperatures, especially for interior Bristol Bay and the
Kuskokwim Valley.

A front moves into the western Bering Sea Monday morning and
progresses eastward through Tuesday afternoon. The front weakens
and loses strength as it approaches the Southwest coast, however,
precipitation is likely to spread inland by Tuesday evening.

&&

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

A shortwave trough emerging out of the North Pacific and
associated strong surface low pressure will cross the western
Aleutians into the Bering on Wednesday, moving northeastward and
approaching the Southwest Alaska coast by Thursday. There is still
disagreement on the timing and exact placement and accompanying
upper level features with this low, but there is the potential for
gale-force winds and enhanced precipitation near the Southwest
coast on Thursday.

Additional shortwave energy will then stream underneath this low
and likely form a new triple point low, but given the timing and
location differences with the main low, the location of this new
low remains uncertain. A faster more progressive solution may
allow the low to form west of the Alaska Peninsula continuing
winds and moisture into Southwest Alaska. However, a slower more
amplified solution could allow this new low to form in the Gulf of
Alaska. Regardless of which solution is correct, precipitation in
the form of snow is possible across Southcentral into Friday.

-ME

&&.AVIATION...

PANC...VFR conditions and light winds will persist. An occasional
gust up to 15 kts is possible through Sunday morning.

&&