355
FXAK67 PAJK 121409
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
609 AM AKDT Fri Jul 12 2024

.SHORT TERM...Active weather pattern continues over the region
with a weakening low pressure over the N gulf the main story for
today. Light on/off precip will diminish through the day with
lowest precip chances this evening. Elevated winds this morning
will ease through the day before rising again tonight into Sat.
Today could be considered the calm before the storm as an
unseasonably strong low will impact the region this weekend into
next week.

.LONG TERM.../Saturday through Wednesday/ Continuing from the
short range, the break over the panhandle will be relatively brief
as our next system moves into the northern gulf by late Saturday
morning. As mentioned in the special weather statement sent out
Wednesday evening, this system is expected to bring a strong
frontal band into the panhandle through the day Sunday and bring
widespread moderate to heavy rainfall through late Sunday night
into Monday morning, with heaviest rainfall expected along the NE
gulf coast and along the Icy Strait Corridor. The orientation and
progression of this front could strongly influence rainfall totals
during this time depending on where the plume of moisture sets
up and how much it wobbles. Ensemble model guidance continues to
support high probabilities of 24 hour precipitation totals greater
than 1 inch for the above mentioned areas. As of this forecast,
the highest rainfall totals are expected along the NE gulf coast
and Yakutat, with a 60% or greater chance of 2.5 inches or more in
a 24 hour period. The expected timing of the heaviest rain
remains Sunday morning through early Monday morning, progressing
from west to east, with peak timing sometime Sunday afternoon or
evening. Through the day Monday the front is expected to begin
shearing apart with moisture transport on a downward trend and as
such should see precipitation begin to lighten up and a potential
transition to showers as opposed to persistent rain. However cloud
cover overall is expected to persist with Wednesday still giving
the best chance for more breaks. With this expected heavy rain,
many area streams and rivers are likely to see significant rises
during this timeframe. Close coordination with the Alaska River
Forecast Center continues as flood potential is assessed as the
event approaches.

In term of winds, this strong frontal band is likely to produce
low end gales west of Yakutat due to development of a barrier jet.
For the NE gulf coast expectations are for high end small craft
winds of around 30 kt by late Saturday night into Sunday morning.
The front will then gradually push inland through Sunday afternoon
and into the evening. This will lead to increasing winds of 15 kt
or more along the front, especially for the northern and central
inner channels. For land areas along the Icy Strait corridor as
well as outer coastal communities, can expect gusts up to 30 mph
with the frontal passage, with winds across the panhandle trending
downwards Monday night into Tuesday.

Looking towards the middle of next week we are likely to have a
brief lull between systems, though the pattern overall looks to
remain active.

&&

.AVIATION... As the next front moves through, conditions throughout
the panhandle will remain MVFR with times of IFR. Times of IFR
will be from lower VIS and lowered CIGS with heavier precipitation.
These lower CIGs and VIS will continue and can cause times of IFR
to LIFR later tonight in the northern panhandle as even heavier
rain enters the area.

&&

.MARINE...Low pressure over the N gulf will slowly weaken and move
inland through the morning. Expect fresh breezes over the N gulf
and N Lynn to ease by late morning. The lull will be brief and
winds will rise again tonight into Sat as a gale low moves into
the NW gulf. This will bring gales to the N gulf and strong to
near gale winds to the inner channels late Sat through early next
week.

&&

.HYDROLOGY...Confidence increasing on anomalous rainfall event
beginning this weekend and persisting into next week. ESAT
indicating IVTs 5-7 std dev above normal and EFI greater than 95%
with SoTs 1-2 for the NE gulf coast and Icy Strait corridor. This
means 24hr rainfall totals over 2 inches along the NE gulf coast
are nearly 100% with the probability of 3 inches around 30%.
These become over 95% of 1 inch and nearly 60% of 2 inch totals
for the Icy Strait corridor including Juneau. This event will be
longer than 24 hours spanning from Sat through Mon. Record daily
rainfall records will likely be set and all area rivers and
streams will see rises from this rainfall.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ652-671-672.

&&

$$

SHORT TERM...BC
LONG TERM....STJ
AVIATION...EAB/BC
MARINE...BC
HYDROLOGY...BC

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