Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
558 PM EST Sun Feb 16 2020
Valid 12Z Thu Feb 20 2020 - 12Z Mon Feb 24 2020
Troughing along 180 is favored late this week through the weekend
and into next week as subtropical ridging off Asia meanders
offshore. Most of the 12Z models were in good agreement to start
as a robust system traverses the eastern Aleutians/AKPEN. The GFS
has remained to the northwest of all other deterministic models
for several days (and stood alone/farthest northwest among all
recent ~90 ensemble members) and was again discounted. Again
followed the lead of the 12Z ECMWF with support from the UKMET and
Canadian as well as the GEFS mean and ECMWF ensemble mean. Parent
low will likely linger in the Gulf through the weekend as the
front pushes through the Panhandle. Models have become more
bullish on a weak trailing front that may attempt to lift toward
at least the southern Panhandle Saturday (GFS farther north than
most) into Sunday. At the same time, another system will likely
push eastward along or just south of the Aleutians through next
Monday. With continued model disparity, relied fully on an
ensemble consensus between the NAEFS and ECMWF ensemble mean which
may take the system toward the eastern Aleutians by the end of the
period as heights rise into the Gulf.
Temperatures near to above average in interior/eastern areas will
trend back toward below average as colder air is dragged down from
the north behind the lead system. The Panhandle should see nearer
to average temperatures (but still trending a bit cooler) with
mainly westerly onshore flow and a nearly daily chance of
precipitation. Highest rain/snow totals are likely over the
southeast side of the Kenai Peninsula eastward across Prince
William Sound to Yakutat and through the Panhandle, perhaps with
additional heavier amounts over the southern Panhandle depending
on the trailing front this coming weekend. More rain/snow will
spread across the Aleutians Sat-Mon as the next system passes
eastward.
Fracasso
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
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