Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
541 PM EST Sat Nov 23 2024

Valid 12Z Wed Nov 27 2024 - 12Z Sun Dec 01 2024

...Much colder airmass to focus over the Interior next week...

...Protracted Wet/Snowy Pattern through the extended Thanksgiving
weekend for Southeast Alaska...


...Guidance Evaluation/Preferences...

Guidance forecast clustering has increased through medium range
time scales, limiting confidence. Prefer a larger scale compatible
12 UTC GFS/ECMWF/UKMET and GEFS/ECMWF ensemble means composite to
maximize forecast continuity amid growing system uncertainties.
The flow pattern next week should be highlighted by a much below
normal cold airmass focus over the Interior and an uncertain
intensity and overall protracted wet/snowy pattern for Southeast
Alaska. There is some guidance that offers stronger potential from
Thanksgiving northern stream energy to monitor and subsequent
impact from later extended holiday weekend slow approach of a
major and moist Gulf of Alaska storm well offshore that will also
support evolving and long duration maritime threats.

...Weather/Hazards Highlights...

Upper ridging in place up into the Interior will break down and
retrograde over the Bering Sea next week, leading to a much colder
and unsettling trend for especially Interior Alaska under renewed
mean upper troughing. As is typical, the coldest readings will be
on the North Slope and central to especially the eastern interior
where below normal temperature anomalies will be most prominent.
Post-frontal gap winds may periodically strengthen in flow over
the southern to southeastern Alaskan tier.

Guidance spread next week becomes more significant over time with
the handling of deep offshore storms re-developing/working from
south of the Aleutians to the Gulf of Alaska. This impacts the
timing for emergence of a subsequent downstream deeper moisture
and enhancing precipitation pattern for the Southeast, perhaps
with heaviest onset and possible heavy snow threat next weekend to
be monitored.

Schichtel


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