Area Forecast Discussion
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FXAK67 PAJK 261418

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
618 AM AKDT Tue Sep 26 2017

.SYNOPSIS...A warm front extending east to west will lift north
across the gulf and the Panhandle today spreading bands of
moderate to heavy rain across Southeast today. Another front
aligned north to south will follow tonight and persist offshore of
the Panhandle into Wednesday. This will keep rainfall in the
forecast through Wednesday night and potentially longer.


.SHORT TERM...Fresh from one day without raincoats, residents and
visitors of Southeast Alaska will need to tolerate several days in
a row of rainfall, some of it heavy through mid-week as a very
moist, subtropical air mass spreads across the area. The fog
issues are a thing of the past, and are now replaced by rain and
wind. Gusts to 35 mph will likely afflict Ketchikan and the coast
today. More wind associated with a stronger front approaching our
area Tuesday night and stalling on Wednesday will result in
stronger winds Panhandle wide. With rainy weather and a well mixed
atmosphere, we expect little diurnal change in temperatures
through midweek.

.LONG TERM.../Thu night through Tue/ A lot of differences with
models and their ensembles for the weekend and early next week.
Many operational models show a low level ridge over the gulf while
the ensemble means (and latest WPC) have a low. Spread is large
in the ensembles and there has been little run to run consistency.
Given that background, opted to leave current forecast as is.

For Thu night and Fri, cold front should slowly move E of the
area and rain should become showers. Cooler air should move in for
the weekend it appears, but the model differences make for a
difficult temp forecast especially the min temps over the weekend.
All in all, confidence in longer range forecast is very low at
this point.


.AVIATION...TAF sites begin with MVMC and IMC conditions from
Juneau/Gustavus south and VMC conditions ahead of the front to
the north. Wind shear persists across the southern areas.
Conditions improve through the day marginally, but should fall yet
again tonight as heavier rain bands focus on the northern


.MARINE...We have elevated wind hazards in the gulf to gale
warnings as the warm front lifts north. Gales will reemerge in
the forecast tonight as a second front aligned north to south
approaches Southeast tonight and Wednesday. In addition, we raised
wind speeds through portions of the Inner Channels including a
small craft advisory for Cross Sound this morning and another for
30 kt in Clarence Strait this morning.


.HYDROLOGY...A warm subtropical air mass with model-estimated
integrated vapor transport values of around 3.5 standard
deviations above normal will enter Southeast Alaska today. Owing
to its origins from the subtropical Pacific, snow levels will rise
prominently as well. There is at least a chance of flooding
Wednesday night in some streams in the north. After analysis later
today, should flooding becoming likely, a flood watch may be
considered. What is certain is that area streams and rivers will
rise significantly through early Thursday, and a special weather
statement continues to cover these possibilities.


.AJK Watches/Warnings/Advisories...
MARINE...Gale Warning for PKZ042-043-051-052.
     Small Craft Advisory for PKZ022-032-033-036-041-053.




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