Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
633 PM EDT Fri Jul 22 2022
Valid 12Z Tue Jul 26 2022 - 12Z Sat Jul 30 2022
***Heavy rain possible across portions of southeast Alaska through
Tuesday and high winds possible Tuesday across western portions of
the state***
...General Overview...
An anomalous cold upper low will be in place across western Alaska
for early next week along with below average temperatures. This
is forecast to weaken going into the middle to end of the week as
a weak ridge axis tries to build ahead of the next trough across
the Aleutians.
...Guidance/Predictability Assessment...
The 12Z model guidance suite is in very good overall agreement for
the beginning of next week and even into Wednesday, and agree on
weakening the deep upper low over the northwestern mainland,
although the GFS is slightly slower in doing so. By the end of
next week, models generally agree on height rises across the
mainland ahead of an amplifying trough over the Aleutians. The
CMC is among the strongest with the Aleutians trough compared to
the weaker and more progressive ECMWF/GFS by next Saturday, but
overall differences at this time scale are less than typically
seen. Therefore, some deterministic guidance can be maintained
through the entire extended forecast period, whilst keeping
contributions from the ECENS/GEFS less than 50%.
...Sensible Weather...60s
Through the course of the extended forecast period, a potent
upper-level low and related surface low pressure system will track
northward from the Bering Sea along the western coastline.
Temperatures will remain cool through midweek, with many locations
expected to be below normal for late July. However, readings will
begin to moderate/warm across the Southwest as weak ridging moves
into the area in the wake of the first system. Another low is
expected to cross the Aleutians by the middle to end of the week.
Overnight lows are forecast to range from the 30s over the Arctic
Coast, to the 40s and low 50s elsewhere. The daily maximums will
likely range from the 50s to 60s south of the Brooks Range,
however a few locations may actually reach the low 70s. Strong
wind gusts will be possible on Tuesday from the Southwest to the
Brooks Range with the Bering low pressure system. Periods of
moderate to heavy rainfall is expected through next Tuesday, which
may lead to areas that receive excessive rainfall and develop
localized flooding concerns. During this time, 3 to 6+ inches of
rainfall is forecast with isolated higher amounts possible.
Hamrick
Hazards:
- Heavy rain across portions of the Alaska Panhandle and mainland
Alaska, Mon-Tue, Jul 25-Jul 26.
- High winds across portions of mainland Alaska, Mon-Tue, Jul
25-Jul 26.
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