198
FXAK02 KWNH 222357
PMDAK

Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
756 PM EDT Wed May 22 2024

Valid 12Z Sun May 26 2024 - 12Z Thu May 30 2024

...Overview...

An upper low over the northeastern Pacific early next week will
spin down as it slowly moves east. Meanwhile there is some
increasing model signal for a small upper low to track from near
the northwest to southwest Mainland. As the week progresses,
troughing/energy are likely to spill east into the Bering Sea and
Aleutians but with low confidence in the details.


...Guidance Evaluation and Preferences...

Model guidance is agreeable with the large upper low and
associated surface low over the northeast Pacific gradually
drifting east while weakening Sunday through midweek. Meanwhile, a
small upper low is showing a bit more consistency among recent
guidance. By Sunday most models have the feature dropped toward
the Bering Strait and vicinity, with the exception of the CMC that
meandered it north of the North Slope. A general drop south is
likely through Monday and Tuesday, but beyond that models diverge
with where that low goes, which is dependent on the upstream
features. Model spread increases quite a bit upstream as larger
scale upper troughing/possible lows and vorticity maxima tracking
eastward. The ECMWF for example pushes some energy east across the
Aleutians Monday-Tuesday while maintaining most energy to the west
near or west of Kamchatka. GFS runs on the other hand consolidate
into one upper low steadily progressing eastward across the
Aleutians Tuesday-Thursday. There is low confidence on how this
will play out but a more troughy pattern is likely over the Bering
Sea/Aleutians in general.

The WPC forecast used a model blend heavily favoring GFS runs and
the ECMWF early in the forecast. Gradually progressed to include
more ensemble means to just over half by Days 7-8 amid the
increasing spread and uncertainty.


...Weather/Hazards Highlights...

Rain amounts should be modest through the period overall. Southern
parts of the Panhandle may see a relative maximum as the northeast
Pacific upper low directs moisture there. Light to moderate lower
elevation rain and higher elevation snow in the southeastern
quadrant of the Mainland to the Alaska Range in particular, with
some light amounts farther west, and by midweek farther north into
the Interior. Energies and possible lows/frontal systems pushing
through the Aleutians to Alaska Peninsula could lead to periodic
precipitation as well. There is some possibility for enhanced
winds across western Alaska early in the week but do not look too
strong.

Interior Alaska is likely to see the mildest temperatures across
the state, with highs generally in the 60s to nearing 70 as the
week progresses with a warming trend. The Brooks Range to North
Slope should also see temperatures warm with time, from around to
above the freezing mark for highs in the Arctic Coast communities.
For the southern coast, temperatures at least for highs are
forecast to stay below normal, with 40s and 50s for the most part.


Tate


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

$$