Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
743 PM EDT Tue Jun 01 2021
Valid 12Z Sat Jun 05 2021 - 12Z Wed Jun 09 2021
...Overview and Guidance Evaluation...
A deep upper-level low is forecast to be located between
northwestern Alaska and Siberia at the start of the medium-range
period this weekend. The ECMWF and CMC tend to dig this upper low
southeastward down the West Coast early next week toward the Gulf
of Alaska. Their ensemble means do not support this scenario,
however. A general model compromise was used to derive the WPC
Alaska medium-range grids. This blend included the 12Z GFS/GEFS,
12Z CMC/CMC mean, and the 12Z ECMWF/00Z EC mean, trending toward
the ensemble means for Days 7-8. With a general model compromise,
the upper low is kept nearly stationary between Alaska and Siberia
during the weekend before lifting and opening up into the Arctic
Ocean, a scenario that agrees better with the GFS. But some
troughing is maintained near the west coast of AK into early next
week. Elsewhere, upper troughing and a surface front appear to
linger near/south of the western Aleutians as weakening impulses
push northward toward the area from the northern Pacific. This
blend also agrees well with continuity.
...Weather/Threats Highlights...
Some enhanced precipitation will linger across the Alaska
Panhandle associated with weakening low pressure systems. Some
moderate precipitation is also forecast near the Tanana River
Valley in southeastern Alaska this weekend before diminishing
early next week. Increasing chance of rain can be expected for
western Alaska and the Aleutians early next week due to
approaching frontal systems. Temperatures are expected to be
above normal for western coastal sections of Alaska but below
normal for the North Slope and for southern and southeastern
Alaska. Much of the interior sections should see highs into the
60s but it will remain quite chilly north of the Brooks Range
where highs should remain in the 30s and 40s.
Kong
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
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