Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
655 PM EST Thu Mar 10 2022
Valid 12Z Mon Mar 14 2022 - 12Z Fri Mar 18 2022
...Overview...
Potent energy is forecast to dive southward into the Alaska
mainland early next week after rounding the northern side of an
upper high over Siberia this weekend. This will create a
southwest-northeast oriented upper trough across the state around
midweek, with an embedded upper low perhaps closing off near or
over the Alaska Peninsula. Farther south, an active storm track is
expected for the northern Pacific influencing southern Alaska with
upper-level shortwaves and surface low pressure systems,
especially for the first half of the week before the flow becomes
more dominated by the aforementioned upper trough, but with some
interaction of the various energies and additional Gulf of Alaska
lows.
...Guidance/Predictability Assessment...
The easternmost upper low transitioning to a trough in a series of
northern Pacific systems is forecast to support a surface low
pressure system moving toward the Alaska Panhandle early in the
workweek. This initial surface low has fairly good clustering
among model guidance, though with perhaps the GEFS and GFS runs
are slightly slow Monday-Tuesday compared to consensus of the
other guidance. Later lows forced by this energy train and
eventually the northern stream upper trough are not quite as
agreeable with the details, led by some differences in the smaller
scale shortwaves that may take until the short range to resolve,
but also related to differences with the trough dropping into the
mainland. For the mainland trough, model guidance has trended
slightly weaker today compared to the previous forecast, but the
westward extent of its reach remains in question. Most
deterministic guidance from the 12Z model cycle showed a westward
shift in the trough/embedded low compared to the ensemble means by
Wednesday-Thursday. At this point it seems too early to tell if
this is a consistent trend to follow or not, since the ensemble
means remained east. The 12Z ECMWF mean that was not available in
time of forecast creation did show a slight westward shift
compared to the previous one, but not to the extent of the
operational runs. By late in the period the ensemble means agree
that the primary focus for low pressure should eventually
gravitate to the northeastern Pacific/Gulf of Alaska due to the
mainland upper trough. However, differences in the placement and
strength of the surface lows remain notable, with a general idea
of ensemble means farther north with the lows and operational
models farther south.
Thus the WPC forecast began with a multi-model deterministic blend
early in the period, but as the period progressed phased in the
GEFS/EC ensemble means, which were at least somewhat well
clustered. Kept mainly the ECMWF in the blend in terms of the
deterministicÂguidance as it may be the best proxy for the
consensus and to keep some depth for some of those lows. This led
to a middle ground solution with positions of the mainland
trough/upper low and surface lows, somewhat favoring the ensemble
means at this point pending future model cycles.
...Weather/Hazard Highlights...
Much of the mainland should see dry conditions during the period,
as precipitation is expected to focus along southern parts of
Alaska given the northern Pacific storm track. The Panhandle in
particular could see rounds of modest to enhanced totals beginning
Monday given moist inflow and a series of low pressure systems.
Some lighter precipitation is also possible farther west, from the
Aleutians to Alaska Peninsula to Southcentral Alaska.
Additionally, brisk winds are possible next week, with current
forecasts indicating gusty winds in the Gulf/northeast Pacific
with the initial low Monday-Tuesday and then breezy northerly
winds over the Aleutians for later in the week.
A transition to colder than average temperatures is forecast next
week for much of Alaska with troughing aloft. This will
particularly be true in terms of highs, which could be 10-30F
below normal for mid-March. The North Slope will be the main area
that can expect near to above normal temperatures. Meanwhile, the
Panhandle should see below normal highs through the period and a
mix of above and below normal lows.
Tate
No significant hazards are expected over Alaska during this
forecast period.
Additional 3-7 Day Hazard Information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
WPC medium range Alaskan products including 500mb, surface
fronts/pressures progs and sensible weather grids can also be
found at:
https://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml
https://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html