Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
630 PM EST Sat Jan 01 2022
Valid 12Z Wed Jan 05 2022 - 12Z Sun Jan 09 2022
...Record cold possible for some areas of the Panhandle next
week...
...Overview...
A blocky pattern will continue through much of the medium range
period over the high latitudes as an upper high over northeastern
Russia/Chukchi Sea meanders in place while reorienting itself.
This favors very cold high pressure over most of the region south
of the Brooks Range, while a storm track near the Aleutians leads
to periods of generally light to moderate precipitation and brisk
winds there, before the possibility of increasing moisture for
Southcentral Alaska by next weekend.
...Guidance Evaluation and Preferences...
Model guidance particularly in terms of the ensemble means showed
reasonably good agreement with the overall blocky pattern, though
with some typical model differences in the details. The upper high
centered over northeastern Russia and the Chukchi Sea still looks
to be oriented west-east on Wednesday before gradually changing
shape and reorienting north-south by Friday, and back to west-east
over the weekend. Its position and orientation were pretty
consistent among model guidance, except for the 12Z UKMET, which
tended to have a westward displacement of the upper high compared
to consensus around days 4-5. Though with some differences in
timing and strength, shortwave energy could drop south through
northwestern Canada on the eastern side of the high and push a
cold front through eastern parts of Alaska late in the week. For
the early part of the period, favored a deterministic blend of the
12Z GFS/ECMWF/CMC, which aligned well with the ensemble means.
By Friday to Sunday (days 6-8), deterministic model variations and
thus uncertainty increase for the prevailing storm track near the
Aleutians and potentially eventually spreading into the Gulf of
Alaska next weekend as the influence of the upper high retracts.
Once again GFS runs retrograde a surface low north of the
Aleutians by Saturday led by different placement of a closed
mid-upper low compared to the EC/ensemble guidance, which is not
impossible but currently contradicts the ensemble guidance.
Favored the ECMWF in terms of the deterministic models instead,
and gradually increased the weighting of the ensemble means
gradually to 50% by the end of the period, but kept a good
proportion of the EC in the blend to enhance strength of features.
...Weather/Hazard Highlights...
Precipitation during the latter half of next week will be
generally limited to light to locally moderate rain/snow over the
Aleutians to Kodiak Island, while much of the mainland should see
dry conditions given periods of high pressure. One exception over
the mainland could be light snow showers for far northeastern
Alaska as a weak surface cold front slips through northwest
Canada. Then by next weekend, a warm front is currently forecast
to push toward or into the Gulf stemming from a low over the
northern Pacific, increasing moisture and potentially spreading
rain/snow into Southcentral Alaska.
Given the cold surface high pressure encroaching into Alaska, much
below normal temperatures remain forecast for the mainland south
of the Brooks Range, gradually trending less extreme with time.
However, temperatures over the Panhandle should stay well below
normal the entire week with offshore flow, and temperatures could
approach record cold for overnight lows and/or daytime highs. The
North Slope will see well above average temperatures midweek
moderating closer to normal by next weekend.
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