Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
800 PM EDT Thu Jul 21 2022
Valid 12Z Tue Jul 26 2022 - 12Z Sat Jul 30 2022
...Heavy rain possible across portions of the southern Alaska and
the Southeast coast through Tuesday...
...High winds possible Monday and Tuesday across parts of
Southwest to portions of the northern Interior...
...General Overview...
Two low pressure systems will lift northward up through the
western half of the Mainland, bringing rounds of moderate to heavy
rain to parts of the south and northwest portion of the Panhandle
along with strong wind gusts from the Southwest.
...Guidance/Predictability Assessment...
Overall, the latest guidance is handling the evolution of the
large scale pattern fairly well even though there are periods
where there are greater model spread with the timing, depth and
location of various features. The most recent runs of the GFS are
trend back toward the rest of guidance and less of an outlier. The
ECWMF/CMC and the respective means have been the preferred
solutions the past several days with light inclusion of the UKMET
and GFS. Today that remains true but more of the GFS was utilized
in the WPC model blend. With improvement in the clustering during
the day 6 and 7 periods, the weighting of the mean made up less
than 50% of blend.
...Sensible Weather...
Through the course of the extended forecast a potent upper-level
low and related surface low pressure system will track northward
from the Bering Sea along the western coastline. Temperatures will
cool through midweek, with several locations to likely to be
cooler than the climatological mean for late July. Temperatures
will begin to moderate/warm across the Southwest as weak ridging
moves into the area in the wake of the first system. Another low
will be lifting through the Aleutians by the mid/late periods.
Overnight lows are forecast to ranging from the 30s to the low
50s. The daily maximums will mostly range from the 40s to 60s,
however a few locations may actually reach the low 70s. Strong
wind gusts will be possible Monday and Tuesday from the Southwest
to the Brooks Range with this system. Multiple rounds of showers
and thunderstorms will pass over the southern part of the state
this weekend and the beginning of the week. Periods of moderate to
heavy rainfall is expected through Tuesday July 26th which may
lead to areas that receive excessive rainfall and develop
localized flooding concerns. During this time 3 to 7 inches of
rainfall is forecast with isolated higher amounts possible.
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
- Heavy rain across portions of the Alaska Panhandle and mainland
Alaska, Sun-Tue, Jul 24-Jul 26.
- High winds across portions of mainland Alaska, Mon-Tue, Jul
25-Jul 26.
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