Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
602 PM EST Wed Jan 22 2020
Valid 12Z Sun Jan 26 2020 - 12Z Thu Jan 30 2020
...Well below average temperatures for most of mainland Alaska...
The guidance continues to offer good consensus that an upper level
ridge will build northward over the Bering Sea Saturday onward,
while an upper level trough anchors itself over the Mainland.
Forecast confidence is high that the implication for much of
mainland Alaska will be strong surface high pressure intensifying
near the Bering Strait, as increasingly cold conditions settle
over most of the state. Both maximum and minimum temperatures
could be near or exceeding 20 degrees F below normal, especially
across the Interior, southwestern Alaska, and the northern Alaskan
Peninsula.
An active North Pacific jet will send various shortwaves/surface
lows across the North Pacific into the Gulf of Alaska, which
should act to reinforce a closed upper low lingering somewhere
near the southern mainland, or northern Gulf. This setup would
keep Southeast Alaska with relatively high precipitation chances
through much of the period. Chilly temperatures would support
snow, not only in the higher elevations, but also working its way
into parts of southern Alaska, and the northern Panhandle.
While models agree on the overall larger scale pattern, they
continue to struggle with the evolution and progression of the
series of surface lows entering the Gulf and how they interact
with the larger scale trough over Alaska. Accordingly, the
specifics of this aspect of the forecast remains more chaotic with
below average predictability. As a result, the WPC progs utilized
the agreeable 12z GFS/ECMWF with the ensemble means for days 4-5,
increasing weighting of the means beyond that time.
Santorelli
Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
Hazards:
- Much below normal temperatures across portions of mainland
Alaska, Sat-Wed, Jan 25-Jan 29.
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