Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
542 PM EST Mon Jan 13 2020
Valid 12Z Fri Jan 17 2020 - 12Z Tue Jan 21 2020
...Overview...
Upper pattern will feature increased troughing across the Bering,
AKPEN, and into the Gulf as an upper high rotates eastward across
the North Slope and into NW Canada before weakening. Well below
normal temperatures in eastern/southeastern portions will slowly
moderate starting this coming weekend as the upper low over the
Panhandle moves westward beneath the upper high. Precipitation
will be confined to the Aleutians Thu-Sat and then focus over the
Panhandle and Southcentral as weak systems rotate into the Gulf.
...Guidance/Predictability Assessment...
The 12Z GFS/ECMWF/Canadian/UKMET offered reasonable clustering
with the 00Z ECMWF ensemble mean and 12Z GEFS mean to start the
period, Fri-Sun, with the couple systems along 50N. Consensus
approach served well with the latest guidance on the track of the
upper high as well. Thereafter, uncertainty increases with the
smaller-scale systems rotating northward then northwestward into
the Gulf as the mean upper trough pulls westward. Trended toward
an ensemble blend (mostly 12Z GEFS mean and 00Z ECMWF ensemble
mean) to mitigate daily changes in the forecast. Canadian mean was
quite fast with the system just south of the Aleutians next
Tuesday by more than a day. Near the Gulf, weak systems will
maintain a stormy but milder pattern for the Panhandle.
...Weather/Hazards Highlights...
Much of eastern/southeastern Alaska, especially the Panhandle,
will slowly moderate back toward normal temperatures after this
weekend. Above normal temperatures may be limited to the North
Slope. Precipitation will be light overall until later in the week
through the weekend, focused over the Aleutians then to the
Panhandle/Southcentral. Highest amounts may lie over the southern
Panhandle closer to higher moisture values off the Pacific and a
better fetch.
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
- Much below normal temperatures across portions of the Alaska
Panhandle and mainland Alaska, Thu-Sat, Jan 16-Jan 18.
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