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FXAK67 PAJK 010029
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
329 PM AKST Tue Jan 31 2017

.SHORT TERM...Relatively quiet weather across the region through
the next 24hrs. Currently there is a ridge of high pressure over
the eastern gulf which is driving flow over the area to be
northerly, although light. Clouds have been spreading over the top
of the ridge all day and kept things mostly cloudy or cloudy for
the northern and central panhandle. A few showers remain just off
the coast as seen on radar, but these will be diminishing this
evening. Yakutat still has potential for isolated snow showers to
make it over the ridge top from a front to the west, but so far
none have transpired today. If any were to occur it would likely
be very light with next to no accumulation.

Tomorrow the high pressure in the gulf weakens and an inverted
trough will start to form along the coast. This will increase the
pressure gradient with high pressure in the Yukon, causing north
winds to increase through the day, reaching about 20kt in N. Lynn
Canal in the afternoon.

Temperatures were a bit tricky today due to persistent cloud
cover. Cloudy places were able to stay warmer this morning, but
also didn`t get much warming from the sun, so the diurnal range
was around 5 degrees. Southern areas that were mostly clear had a
larger diurnal range of around 10 degrees. Thinking that there
should be fewer clouds tomorrow, so expect colder temperatures
when you start the car in the morning but a good rebound in the
afternoon with near normal highs.

Used mainly the NAM12 for minor changes to this forecast package,
but other models were utilized for some elements along with
adjustments for local effects. Forecast confidence is above
average, but slightly lower for cloud cover.

.LONG TERM...Main focus of the long range remains the strong cold
air outflow for later this week. Very cold air mass dropping into
the southern Yukon and northern British Columbia late week as 850
mb temps drop to around -20 to -25 C. The cold air will cause
MSLP in the southern Yukon to rise up to 1045 mb. The combination
of the strong pressure gradient across the northern panhandle and
the plentiful cold air spilling through the mountain passes will
generate gale force winds in many of the northern inner channels
and northern gulf Thu into Fri night (storm force winds are also
possible in Lynn Canal as well). In addition a prolonged Taku Wind
event is also possible for the downtown Juneau and Douglas area
Thu night into Fri night. Cross barrier flow is forecast to reach
around 60 to 70 kt with a strong inversion present. A critical
level is also present but it is more speed shear rather then the
directional sheer that is ideal. Still this should be enough for
at least strong wind gusts in the usual Taku wind area.

Winds diminish into the weekend as the cold air moves off to the
east. A lingering surface inverted trough over the panhandle and a
strong blocking upper ridge to our west will keep us dry at least
through Monday. After that point some models are starting to break
the ridge down or retrograde it to the west opening the door for
some potential wetter weather to move in for mid next week. Model
agreement is not that great however so kept chance pops and
mostly cloudy skies going for the extended using WPC for most
extended updates.


&&

.AJK Watches/Warnings/Advisories...
PUBLIC...None.
MARINE...Small Craft Advisory due to Seas for PKZ041>043-051-052.
&&

$$

Ferrin/EAL

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