Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
415 PM EDT Thu Sep 19 2019
Valid 12Z Mon Sep 23 2019 - 12Z Fri Sep 27 2019
Through the extended period a mean upper-level low will be
positioned over the Bering Sea and during this time, multiple
longwave troughs will send low pressure systems across the
Aleutian chain through the Gulf of Alaska and into Southern
Mainland/Southeast and western Canada. This setup will favor a wet
pattern for southern portions of the Mainland and the panhandle.
Weak ridging is also expected to setup over parts of western
Canada/Alaska as the week progresses - this will help transition
from a cool and wet pattern to a drier and near normal air mass
across the northern part of the state.
Model guidance and the ensemble means are in fair agreement with
the synoptic pattern; however the deterministic guidance has
noticeable timing/strength differences with each of the passing
shortwaves. At times the CMC lagged behind consensus while the GFS
was faster and deeper. This forecast package primarily used the
ECENS/GEFS/NAEFS means along with some inclusion of the ECWMF and
GFS; which helped mute some of these differences.
Campbell
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:
- Heavy rain across portions of the Alaska Panhandle, Mon-Tue, Sep
23-Sep 24.
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