Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
753 PM EDT Sun Aug 29 2021
Valid 12Z Thu Sep 02 2021 - 12Z Mon Sep 06 2021
...Heavy rainfall possible for portions of the southern Coast
region during the middle part of next week...
...Pattern Overview and Model Guidance...
The models have been persistent with the evolution of the
upper-level trough and the surface low pressure systems that track
across the Gulf of Alaska. The ridging in place over the Interior
and the Southeast is expected to drift to the east as the trough
progresses eastward from the Bering Sea. In general, the latest
guidance remains fairly clustered given the typical spread on
specific details. Again, the approach of utilizing a blend of the
12Z ECWMF/CMC/GFS and 06Z GFS and their associated ensemble means
helped smooth out the spread. The models are in agreement where
the higher QPF will set up along the coast and adjacent locations
through day 6 and begins to differ a little for the remainder of
the extended period, especially across the Panhandle.
...Sensible Weather...
Moderate to heavy rain will spread from the Aleutians to the
southern coast of the Mainland by midweek and to the Panhandle by
Friday. Rain will decrease over the western portion of the
southern Coast while persisting over the Southeast this weekend
and into early next week. Portions of western and eastern Interior
may have a few showers this weekend as well as the frontal
boundary will be draped across the northern Gulf of Alaska. These
areas may also experience gusty winds. Initially, temperatures
across parts of the Interior and Southeast may be above seasonal
normal but will return to normal as the cloud cover and rain
increases.
Campbell
Additional 3-7 Day Hazard Information can be found on the WPC
medium range hazards outlook 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