Area Forecast Discussion Issued by NWS Anchorage, AK
000
FXAK68 PAFC 140033
AFDAFC
Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
433 PM AKDT Wed Mar 13 2024
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: This
afternoon through Saturday afternoon)...
Few changes to the forecast through Friday afternoon. A strong
storm system will bring warmer, wetter, and windier weather from
Friday evening through Saturday, but forecast confidence remains
low due to poor model agreement.
As seen on radar, snow showers continue to move into Prince
William Sound and across Kenai Peninsula, the last vestiges of the
system that brought yesterday`s heavy snowfall. These showers may
be heavy at times, but they will gradually taper off through
evening. Then attention shifts towards a low currently moving into
the Gulf from the North Pacific. This North Pacific low had
previously been a major source of uncertainty, but models have
finally converged on a solution, leading to improving forecast
confidence. Overall, impacts should remain minor with this
system. Gusty gap winds will pick up, especially out of Whittier
and Valdez/Thompson Pass, but precipitation will be largely
limited to the Copper River Basin. This means that there will be
minimal threat of significant visibility reductions in blowing
snow.
By Thursday afternoon, several shortwaves will move across the
north Gulf coast behind the departing low. These shortwaves will
help drive snow showers along Prince William Sound and Kenai
Peninsula. Due to uncertainty in where showers will be most
prolific, forecast snow amounts may be a bit underdone.
Regardless, total snow accumulations are not expected to be more
than a couple inches.
Much higher precipitation amounts are expected from late Friday
through Saturday, as a strong front moves west to east across
Southcentral. Forecast confidence remains low, with high
uncertainty and model spread. This forecast package has delayed
the arrival of the front from the overnight forecast package, but
major shifts in timing and other forecast details remain possible.
What we do know is that this system will bring stronger winds,
moderate to heavy precipitation, and warmer air, with moderate to
high confidence that many locations will warm into the high 30s
and low 40s by Saturday afternoon. Likely the biggest forecast
question will revolve around precipitation - where precipitation
will be greatest/how much downsloping is expected, if/when
precipitation will transition from snow to rain at lower
elevations, and how much snow versus how much rain is expected.
Stay tuned as we monitor this system and continue to refine the
forecast.
- KC
&&
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (Days
1 through 3)...
A deep trough over Southwest Alaska continues mostly dry
conditions with the cold arctic airmass expected to remain in
place through Saturday.
A robust low off the coast of Kamchatka continues to push a front
with near storm force winds and a mix of rain and snow into the
western Aleutians. As this front approaches ridging over the
Bering, it will slow down significantly but slowly weaken as it
approaches the central Aleutians late Thursday into Friday,
continuing areas of light to moderate precipitation. Northerly
flow will also continue scattered snow showers across the
Aleutians over the next few days.
Precipitation chances return to the Alaska Peninsula late
Saturday into Sunday as a North Pacific low moves into the western
Gulf, however, confidence in the exact timing and the western
extent of any snow remains low.
-ME
&&
.LONG TERM FORECAST (Days 4 through 7) Sunday through Wednesday...
A large Arctic upper level trough stretching over the Bering
continues to deepen and regress through the forecast period. In
the East, a ridge continues to build over Mainland Alaska,
expanding to cover the the Interior and influences Northern Alaska
weather by the end of the period. These two features help steer
surface lows and fronts across the region, with most of the active
weather occurring across the Southern half of the state.
A couple of well developed lows to the South of the Aleutians
spread their fronts over the Aleutians and Southern Bering. The
first moves across the Aleutians starting Sunday, and crosses the
Alaska Peninsula for Wednesday. The second moves over the Western
Aleutians by Wednesday. Locally heavy rain and snow mixed becomes
rain will spread over the Central Aleutians Monday and Tuesday,
and into the Eastern Aleutians and AKPEN into Wednesday. Gusty
Easterly winds starts Sunday over the Western Aleutians, becoming
Southerly with possible gale force winds over the Eastern
Aleutians and AKPEN Tuesday through Wednesday.
The remnants of a front will spread precipitation from Kodiak
Island along the Eastern Kenai into Prince William Sound, but
concentrates its energy further East on Sunday. The Southeast will
draw a break as the ridge continues its build over the state
through Wednesday. Warmer temperatures and rainfall will move over
Kodiak Island and Cook Inlet through Wednesday.
-Kutz
&&
.AVIATION...
PANC...VFR conditions and light winds will persist.
&&
$$