Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
639 PM EDT Thu Jun 24 2021
Valid 12Z Mon Jun 28 2021 - 12Z Fri Jul 02 2021
...Unsettled weather expected from portions of the Aleutians to
the Southern Coast...
...Overview and Guidance/Predictability Evaluation...
The latest models and ensembles show very good agreement that an
upper low will drift slowly eastward over or just south of the
Aleutians, essentially becoming blocked by upper level ridging
building over the Mainland Wednesday-Friday. Perturbations
rounding the base of the trough will send a couple of waves of low
pressure/systems into the Aleutians through much of next week.
Details, especially the second half of the period, become more
uncertain, but models have trended in the direction of a
stronger/deeper low affecting the Aleutians while upper ridging
across the state may hold off a few days as troughing moves
quickly from Alaska into western Canada by mid-week. To mitigate
the smaller scale, less predictable, features, WPC trended towards
a 50/50 model/ensemble blend by day 8. The first half of the
period leaned very heavily on the 12z operational model runs
(GFS/ECMWF/CMC).
...Weather/Threats Highlights...
Surface lows and fronts ejecting into the Aleutians next week is
expected to set up a wet and windy pattern from especially the
eastern Aleutians into the Alaska Peninsula and parts of the
Southern Coast. This should bring at least moderate rainfall to
the region, although exact amounts remain uncertain. Gusty winds
will also accompany these systems as they cross the region. In
terms of temperatures, upper troughing across the state Monday and
Tuesday will keep temperatures cool, especially across the Brooks
Range and northern Slope region where daytime highs as much as 20
degrees below normal are possible. As upper level ridging builds
over the state during the later half of next week, temperatures
should warm to modestly above normal, with pleasant highs in the
70s for parts of eastern Alaska. Southern Alaska and back to the
Aleutians should remain near or below normal underneath cloudy
skies and unsettled conditions.
Santorelli
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:
-No significant hazards are expected over Alaska during this
forecast period.
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