Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
643 PM EST Sat Mar 05 2022
Valid 12Z Wed Mar 09 2022 - 12Z Sun Mar 13 2022
...Overview...
A persistent upper high atop eastern Russia and the Chukchi Sea
will help promote above normal temperatures particularly for
northern and eastern parts of Alaska during the period (next
Wednesday to Sunday). Mainland Alaska will generally be in a col
pattern between this feature, rounds of upper troughing/lows over
the Aleutians, ridging over the East Pacific that should get
shunted eastward by late week, and periods of troughing in the
northeastern part of the state. This should lead to unsettled
weather particularly over the Aleutians, with some precipitation
spreading east in the southern half of the mainland and Panhandle.
...Guidance/Predictability Assessment...
Recent model guidance is generally most agreeable with the upper
high to the northwest of Alaska, with more variability among
models to the south and east. Upper lows and energy are forecast
to meander across the Aleutians and the surrounding waters,
supporting development of likely several surface lows during the
period. The details of these smaller scale features within this
broader troughing pattern are quite uncertain and will likely take
a few more days for models to converge properly. Regardless,
models generally show some of this energy spilling eastward to
shunt the East Pacific ridge east into North America by late week,
though with some timing differences. Another uncertain part of the
forecast is how much troughing/energy can influence eastern Alaska
at times, to the east of the blocking upper high. In general the
12Z guidance suite indicated stronger energy there compared to
previous cycles (with the ECMWF the strongest) by late next week,
which led to a more stationary high compared to the previous
forecast that had the high migrating farther into the Chukchi Sea.
There is low confidence with these high latitude features though.
Given the somewhat agreeable overall pattern but the ample
differences in the details, the WPC forecast was based on a blend
of the ECMWF/GFS/UKMET early in the period, transitioning to a
ECMWF/ECens mean/GFS/GEFS mean by the latter part of next week
into the weekend. The CMC was excluded this time given some
differences from consensus particularly in the northern Pacific.
...Weather/Hazard Highlights...
A series of lows (and triple point lows) will rotate through and
reform near the Aleutians through the extended period. This will
keep much of this part of the region unsettled, with periods of
enhanced rains/winds for the Aleutians. Modest precipitation is
expected to spread eastward into southern parts of the mainland
and then the Panhandle for the latter part of the week as ridging
shifts away from the state. The heaviest amounts are forecast
along the coast, but some snow should spread farther north in the
mainland as well.
Milder temperatures than normal are forecast for much of the
mainland through at least midweek, particularly in terms of low
temperatures that should be 15-30F above average, while highs
10-20F above normal are expected especially for northern and
western parts of the state. Temperatures should moderate closer to
normal by next weekend but remain above average for western
Alaska, while the Panhandle and eastern mainland are cooler.
Tate
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