809
FXAK02 KWNH 192342
PMDAK

Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
741 PM EDT Wed Jun 19 2024

Valid 12Z Sun Jun 23 2024 - 12Z Thu Jun 27 2024

...Overview and Guidance Evaluation/Preferences...

During the extended period there will be three main low pressure
systems of interest. One will be a slowly retrograding polar upper
low moving across eastern Siberia, another with be a surface
low/upper low tracking in the general direction of the southern
Southeast Panhandle this weekend, and finally a third system
tracking south of the Aleutians. The guidance is hinting that
there may be a fourth system that approaches the western Aleutians
by middle of next week, although details are uncertain.
Meanwhile, most of mainland Alaska will be between these Pacific
storm systems and an arctic upper trough north of the state, with
pleasant early summer weather expected south of the Brooks Range.

In general, there was fair agreement will the large scale pattern
through most of the extended period. Opted to begin with a
multi-model blend of the ECWMF, GFS, CMC and UKMET for the first
couple of days before dropping the UKMET, reducing inclusion of
the CMC while adding in the ECWMF and GEFS ensemble means for the
later period. As previously noted, the spread in guidance
increases a fair amount for the last couple of days of the
extended which lowers confidence on the exact track of the last
system near the Aleutians. This approach provided decent forecast
continuity.

...Weather/Hazards Highlights...

Increasing chances for light to moderate rain is expected for much
of the southern tier of the state and in the vicinity of the
Brooks Range through the extended period. Some showers are also
likely across the central and eastern Aleutians as the next low
pressure system passes by to the south. For the Interior, the
possibility for thunderstorms and dry lightning strikes during the
afternoons and evenings may increase the risk for fire weather
concerns given the dry fuels across the region. Areas north of the
Brooks Range will likely remain dry through the week.

Weak ridging across the Mainland will lead to near normal or
slightly warmer than normal temperatures. Afternoon maximums are
expected to climb into the 70s for many areas across the Interior,
perhaps reaching 80 degrees for the Yukon Flats, and also just
north of the Alaska Range.  Overnight lows here should also be
rather mild with readings bottoming out from the upper 40s to
upper 50s.  The Arctic Coast will likely remain chilly with
onshore flow from the Arctic Ocean, with highs generally from the
upper 30s to upper 40s.

Campbell/Hamrick


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

$$