Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
711 PM EDT Thu Oct 22 2020
Valid 12Z Mon Oct 26 2020 - 12Z Fri Oct 30 2020
...Heavy precipitation possible for the Panhandle and coastal
Southcentral areas late weekend/early next week...
...Guidance/Predictability Assessment...
Generally speaking the latest guidance shows multiple waves
passing through the Gulf and skirting the southern part of the
state. Spread intermittently increased especially with the low in
the central Pacific that lifts northward into the region.
Yesterday the GFS was on the cusp of the envelope; however, today
its evolution of the features are fairly inline with the EC, CMC
and the means. The consensus for this package was to incorporate
the 12Z GFS/ECWMF/CMC and with time increasing the weighting of
their respective means.
...Weather/Threats Highlights..
Heavier precipitation is expected across the panhandle and
portions of the far southern Mainland over the next week as
multiple frontal waves pass through the Gulf of Alaska and
progress onshore. During this time, several locations could pick
up several inches of rainfall. And for the highest terrain, snow
accumulations of a few feet will be possible.
Also during this period temperatures will largely remain
above/much above normal for the Mainland and areas north of the
Alaska Range. The areas with the strongest departures from normal
will be western Mainland and along the North Slope. Once the cold
front approaches early in the week, temperatures will begin to
cool and trend toward normal. Given the cloud cover and rounds of
precipitation across the southern/southeast parts of the state,
daily temperatures will more than likely be below normal through
next weekend.
Campbell
Hazards:
- Heavy precipitation across portions of the Alaska Panhandle and
mainland Alaska, Sun-Mon, Oct 25-Oct 26 and lower Alaskan
Panhandle, Sun-Thu, Oct 25-Oct 29.
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