National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXAK67 PAJK 121323
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
523 AM AKDT Fri Apr 12 2024

.SHORT TERM...

Key Message:
-An approaching front will bring intermittent rain and snow
 showers to the area and increase winds up to Small Craft Advisory
 within inner channels this afternoon through Saturday morning.

Discussion:
No major changes in the short term forecast at this time.
Anticipating wet conditions to remain on tap as approaching
mid/upper level long wave trough and an attendant surface front
will bring intermittent rain and snow showers to southeast Alaska
through the weekend. As the front approaches the area, expecting
it to lose upper LVL support, weaken and eventually stall over the
panhandle. Snow levels will remain fairly low aided by lingering
cooler temperatures at 850 mb. As a result, still thinking that
snow will mix in at times through today and tonight, with some
minor snow accumulations being possible across northern portions
of the AOR. Anticipating this trough to become a closed mid/upper
low as it traverses down the eastern Gulf of Alaska through
Saturday afternoon into Sunday night. PoP chances decrease Sunday
into the first half of the week as a stout mid/upper LVL ridge
pushes in from the west.

.LONG TERM...
Relatively quiet mid to long range forecast with the most active
portion front loaded Saturday morning. Covered mainly by the short
term discussion, a front will make its way through the panhandle
Friday into Saturday morning. By Saturday afternoon, stratiform
precipitation will transition to convective showers as the post
frontal environment pushes into the AOR. As precipitation changes
to showers with the introduction of minor CAA in the 850-700 mb
layer, the likelihood of snow increases. Do not expect any
significant snow accumulations, if any. In fact, as CAA advection
moves over the area with temperatures rising from breaks in
clouds, the atmospheric profile could support ice pellets and
graupel. Kept rain and snow in the forecast to represent the many
things inbetween (except freezing rain).

As time progresses, the trough aloft moves off to the southeast
and a broad ridge replaces it. From this somewhat flat ridge,
northerly, dry winds begin to infiltrate the panhandle with a
surface ridge developing in the Yukon and over the gulf waters.
The result is clearing skies with lighter winds and relatively
warmer temperatures. There is the chance for a marine layer to
develop over the gulf waters, however, current thoughts is that
even if one develops, it will not work its way into the land areas
of the AOR with broad north to northwesterly winds in the gulf.
There is the chance that areas along the NE gulf coast will see
some cloud cover and possibly rain, but this chance was discarded
for this forecast until better confidence can arrive at this
solution.

Leaned a bit heavier on the GFS runs as the 12z deterministic GFS
run matches LREF ensemble mean guidance and the EC AIFS and ML
12z runs on days 4 and 5 onwards. For significant changes to the
forecast, reduced the chance for PoPs significantly on days 4 and
5. Additionally, kept enhanced southerly winds in Lynn Canal and
Stephens Passage for longer through the early portion of day 3.
Lee side troughing from westerly winds over mountain ranges will
likely help these winds blowing for longer. Beyond day 5 however,
significant model divergence has led to rather low confidence with
no clear trend.

&&

.AVIATION.../12z issuance/...The next frontal passage is expected
today, bringing rain and lowered flying conditions. VFR lowering to
MVFR is mainly expected, with isolated and short-lived IFR
conditions possible.

This front will move from north to south through Friday with
leftover showers lingering around the area Friday night into
Saturday.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Strong Wind through this evening for AKZ318.
MARINE...Gale Warning for PKZ652.
     Small Craft Advisory for PKZ012-013-022-031>034-641>644-651-
     661>664-671-672.

&&

$$

SHORT TERM...NM
LONG TERM....NC
AVIATION...GJS

Visit us at http://www.weather.gov/Juneau