650
FXAK02 KWNH 182327
PMDAK

Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
727 PM EDT Tue Jun 18 2024

Valid 12Z Sat Jun 22 2024 - 12Z Wed Jun 26 2024

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

There will be three main low pressure systems of interest in the
extended forecast.  The first will be a slowly retrograding polar
upper low across eastern Siberia, a surface low/upper low tracking
in the general direction of the southern Southeast Panhandle this
weekend, and a third system tracking south of the Aleutians.
There may be a fourth system on the distant horizon that
approaches the western Aleutians by next Wednesday.  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.

The 12Z model guidance, along with the 18Z GFS, are in good
overall agreement across the Alaska domain to start the forecast
period Saturday, with a general deterministic model blend
sufficing as a good starting point for fronts and pressures, and
mainly a GFS/ECMWF blend for QPF with some ensemble biased
corrected QPF. Going into Sunday, there are some minor placement
differences with the polar low over eastern Siberia, but more
noticeable with the weaker upper trough/surface low near the
central Aleutians with the GFS stronger and more progressive.
Model differences grow quite a bit going into the first half of
next week across the North Pacific, and also across the northern
half of the mainland as a potential second polar low drifts south.
 There is a broader signal in the guidance for another low
pressure system approaching the western Aleutians next Wednesday,
albeit with limited confidence on specifics.  The ensemble means
accounted for about half of the forecast blend going into
early-mid next week.

...Weather/Hazards Highlights...

Light to moderate rain will be on the increase this weekend across
the Southeast Panhandle with the approach of the Gulf low along
with gusty southerly winds, followed by more showery conditions
Sunday as the low weakens.  Some showers are also likely across
the central and eastern Aleutians as the next low pressure system
passes by to the south.  Isolated to scattered showers and storms
are expected for portions of the Interior and the Alaska Range,
mainly during the afternoon and evening hours.  Given dry fuels
for portions of the Interior, there are some potential fire
weather concerns with dry lightning strikes.  Most areas north of
the Brooks Range should remain dry through the forecast period.

In terms of temperatures, afternoon highs are expected to reach
well 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.

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

$$