Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
357 PM EDT Fri Sep 20 2019
Valid 12Z Tue Sep 24 2019 - 12Z Sat Sep 28 2019
The mean pattern for the extended periods has a low/trough over
the Bering Sea and ridging over western Canada/eastern Gulf of
Alaska. Guidance shows that multiple low pressure systems will
track from the Bering Sea across the Aleutians into the central
Gulf and portions of the Mainland. However, model spread/phasing
begins by the 24th and increases through the end of the forecast
period. The models seem to be struggling with the evolution of
Typhoon Ta pah, which is contributing to the strength of
pressures, timing and track. This forecast package primarily used
nearly 50% weighting of the ECENS/GEFS/NAEFS means and about 50%
ECWMF and GFS.
In general, this will be favorable for wet conditions for southern
portions of the Mainland and the panhandle. The ridging will help
the northern part of the state transition from a cool and wet
pattern to a drier and near normal air mass.
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