Area Forecast Discussion
Issued by NWS Juneau, AK

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FXAK67 PAJK 031459
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
659 AM AKDT Mon Aug 3 2020

.SHORT TERM.../Monday through Tuesday/ The short term remains
active with showers continuing today with more steady rain
expected for Tuesday as a front moves through. Slight ridging
builds over the region through the afternoon ahead of the next
weather system moving into the western gulf. The surface ridge
axis will be right over the Panhandle keeping moist onshore flow
and showers present. By tonight, an area of low pressure in the
western gulf moves eastward while swinging a front into the
Panhandle late Monday night through early Tuesday morning. As the
front approaches, the surface ridge will sharpen increasing
southeasterly winds throughout the Inner Channels to 15 to 20 kt.
As the front pushes through, expect an area of SCA winds to spread
northward overnight through the central gulf and coastal waters.
After the frontal passage, the gradient takes on a more easterly
component and continues to sharpen with SCA conditions developing
in the Southern Inner Channels overnight while winds in Lynn Canal
subside due to a more parallel gradient.

The gradient remains tight on Tuesday as a wave rotates around
the low in the gulf. This will keep winds over the Inner Channels
at 15 to 25 kt through Tuesday night. The strongest winds are
expected in the southern Inner Channels and E to W oriented water
ways. As the wave rotates northward, precipitation, already
ongoing, will increase in intensity especially across the Southern
Panhandle and Coast Mountains. A plume of moisture will be drawn
northward by an approaching jet streak Tuesday evening with IVT
values around 500 pushing into the southern Panhandle. Rain could
be locally heavy at times.

Overall forecast confidence is above average as models are all in
agreement with the current weather pattern. Used the NAM Nest and
hi-res models to increase winds with the approaching front and
waves through Tuesday.

.LONG TERM.../Wednesday through Monday as of 10 pm Sunday/ Active
weather pattern for SE Alaska continues through the long range
forecast as series of lows/fronts track into the AK Gulf. For
Wednesday the previous days low weakening to an open wave trough
as it moves into the SE Gulf. Precipitation and winds will
diminishing from north to south was the low exits the region by
early Thursday. The northern areas may get bit more drying due to
offshore flow as the low center moves towards Dixon Entrance. an
dry period will be short lived as the next front, associated with
a low pushing into the NE Gulf, crosses over the Eastern Gulf and
over the Panhandle Thursday evening into Friday. Expecting
approximately 1-1.5 inches of rainfall thru Friday. Strongest
winds expected Friday due to the advancing front with gulf winds
in the 20 to 30 kt range and inner channels of 10 to 20 kt.
Generally cooler temperatures with highs in the low 60s to upper
50s and lows in the low 50s to upper 40s. Beyond the end of the
week significant model spread on timing and position of the next
feature develops.

Good confidence that SE AK will be in a wet pattern but low
confidence in details, even at the start of the long range. Used
a blend of GFS/ECMWF for Wednesday but still uncertainty the gulf
low position. Getting better resolution for the next front
however still used ensemble approach with WPC solution.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ035-036-041>043-051-052.

&&

$$

CM/PRB

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