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FXAK67 PAJK 161239
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
439 AM AKDT Mon Sep 16 2024

.SHORT TERM...Chances of rain showers continue across the northern
half of the area through the day on Monday, while a stronger low
passing across the southern half of the panhandle brings
widespread rain to areas south of Sumner Strait. Drier weather is
in store Monday night into Tuesday.

Satellite and radar imagery as of the time of writing (12z)
depict a developing low moving into the southern panhandle, with
its associated cloud shield reaching as far N as the Icy Strait
Corridor. Upper level analysis reveals the culprit behind the low
as a weak upper level shortwave trough moving within a broader
area of troughing across the gulf. Overall dynamics aren`t all
that conducive to a strong system developing, and the primary
impact of this system will be the rainfall it produces across the
southern half of the area through the day. The rainfall itself
will also be less than outstanding, with amounts near sea level
between 0.25 and 0.75 inches of rain expected through the daytime
hours. Across the northern panhandle, chances of rain showers are
expected given continued onshore flow, although these will be
less widespread in nature.

Chances of rain will diminish through the evening and overnight
timeframe on Monday across most of the area as northerly flow
develops, with most locations drying out save for a few passing
showers by Monday night. The exception to this will be parts of
the far southern panhandle like Revillagigedo Island and Hyder,
where PoP chances will remain more robust until Tuesday morning.

As PoPs diminish, increasing breaks in the clouds will set the
stage for fog or low stratus development across parts of the
area, though this will largely dissipate through the morning
hours on Tuesday.

Winds will continue to diminish through Monday, with Lynn Canal,
the Icy Strait Corridor, and Clarence Strait likely remaining the
last holdouts for elevated winds, through even these areas,
barring Clarence Strait, will drop below 15 kt by late Monday
night. Primary changes to the forecast were to add some additional
detail to the PoP and QPF fields for the low moving in across the
south, as well as to extend the duration of elevated winds for a
few locations given a continued sharp pressure gradient.

.LONG TERM.../Tuesday through Friday/...
Quick Notes:
-Rainy weather continues.
-24 hour rainfall amounts are not out of the ordinary for this
 time of year.
-Marine winds will be elevated late Tuesday night through
 Wednesday night with sustained winds around 15-25 kts for some
 of the inner channels.

Details:
The active pattern will continue across the panhandle through
next week.

To start off, an exiting system on Tuesday with brief 500mb ridging
may give the area a short break in the rainy weather, and even some
breaks in the clouds, on Tuesday.

The short break will come to an end Wednesday as the next front
pushes through. There will be both wind and rain with this front.
That being said, rainfall amounts aren`t all the impressive for this
time of year, with 24 hour rainfall amounts around 0.50 to 1 inch.

Wind speeds will increase as the front tracks through, but nothing
too out of the ordinary with frontal passes this time of year.
Beginning late Tuesday night, most inner channels will see speeds
increase to around 10 to 20 knots for Wednesday. The exception
will be Lynn Canal where sustained speeds upwards of 25 knots are
possible based on forecasted pressure gradients.

Once the front clears the area, lingering light, on/off rain will
last through Friday with decreasing wind speeds.

Ultimately, what is currently on the radar as the next impactful
rain event could possibly be next weekend, into early next week.
There are early indications of a long duration rain event. At this
time, there is 40-60% chance of IVT values exceeding 250 kg/m/s for
three days. Unfortunately, details are scarce, but it will be
monitored closely.

&&

.AVIATION...Areas of rain and some fog/low clouds are making for
a mixed bag of aviation conditions this morning. Ceilings and
visibility range from VFR (6000 ft ceilings and 10 mile vis) all
the way down to LIFR (200 ft ceilings and 1.5 mile vis) in some
areas. Winds are mostly light except for the northern Lynn Canal
area where gusts to 40 mph are being observed. The forecast is for
general improving conditions through the day with most areas
becoming VFR by late afternoon. The southern panhandle will be the
slowest to improve as there is a disturbance moving through that
area this morning. Winds near Skagway will likely persist through
the day before diminishing this evening. Tonight will possibly
bring a mixed bag of ceilings and vis conditions again. This time
due to fog possibly developing in many areas and persisting into
Tuesday morning. Expect areas of VFR with IFR or lower conditions
where fog develops.



&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Strong Wind until 7 AM AKDT this morning for AKZ318.
MARINE...Small Craft Advisory for PKZ012-013-022-641>644-651-652-661>664-
     671-672.

&&

$$

SHORT TERM...GFS
LONG TERM....GJS
AVIATION...EAL

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