Area Forecast Discussion
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FXAK67 PAJK 152251

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
151 PM AKST Mon Jan 15 2018

.SHORT TERM.../Monday night through Tuesday night/...With a quick
succession of fronts continues to move across the forecast area.
Another warm front moved over the panhandle from south to north
today, but was significantly weaker and did not produce as much
wide spread precipitation as those in recent days. Today`s front
did not have nearly as much warm low level air behind it either
with observed temperatures through this afternoon ranging from the
mid 40s to the mid 50s. Although not as warm as yesterday, new
record high temperatures for today are likely. Hyder and Skagway
are the exceptions only reaching into the mid to upper 30`s.
Tuesday will feature a mild cold front that will lower daytime
highs tomorrow 5 to 10 degrees.

Satellite and radar data are showing the bulk of the clouds and
precipitation from the present system to be moving west-northwest.
With limited easterly progress, the cold front tonight may not be
overly impactful away from the central and northern outer coast.
Orographic lifting along the coast mountains south of Tracy Arm
should result in enhanced precipitation there as well. Total rainfall
amounts will not be particularly note worthy, with a quarter of
an inch or less overnight. The front will ride over the Coast
Mountains and fall apart Tuesday.

Gale force southerly or southeasterly winds are forecast over the
gulf in advance of the front tonight and are expected to last
through late Tuesday night with little to no post frontal wind
shift. Typical small craft responses expected over the inner
channels with southeasterly gales over Clarence Strait by mid day
tomorrow. There are some indications that the front may go aloft
as it moves inland over the panhandle, which would result in less
gusty conditions than were experienced Sunday night.

GFS and NAM were the favored models. Brought temperatures
up a degree or two in a few locations overnight, otherwise the
temperatures showed a good trend with the cold front moving in
Tuesday. Used the GFS to update the precipitation related parts of
the forecast that resulted in little overall change.

.LONG TERM...Wednesday through Monday...We appear to be in store
for a relatively active pattern through the end of the week and
into the weekend. As the upper level ridge over western Canada
continues to break down further and push east, a very broad
trough with embedded shortwaves will build largely over the gulf.
Current model analysis generally agrees that these shortwaves, and
their associated surface lows, will stay on a mostly southeastern
trajectory through the eastern gulf. Fortunately, this means that
the subsequent positions of these incoming shortwaves indicate a
drier pattern for the panhandle, as it should provide enough
offshore flow to keep northern locations with relatively lower
chances for precipitation. Depending on the exact position of the
surface features that develop, which major models generally
disagree on at this point, southern areas of the panhandle may see
some additional precipitation with the passing of these systems.

For the most part, we`ve trended temperatures downward in the
forecast, especially into the weekend. Potential temperature
analysis shows much colder air wrapping in aloft beginning Friday,
and model spreads also imply cooler air moving in at the surface.

We used the GEM for updates in the Wednesday through Thursday
timeframe and elected to remain with WPC guidance past this point,
as major models do not agree on the position and timing of surface


.AVIATION...Some wind shear remains in panhandle TAFs, but the
parent circulation for the front tonight will remain far enough
offshore that the bulk of the turbulence should remain offshore.
Generally, MVMC will prevail over the next 24 hours due to both
lower CIGS and reduced VSBY at different times. There are areas of
VMC out there as of this afternoon, but confidence in conditions
remains this good as the next front moves in is not good. Periods
of IMC primarily due to reduced VSBY in fog are also expected and
have already occurred over the far northern inner channels.


.AJK Watches/Warnings/Advisories...
PUBLIC...Strong Wind until noon AKST today for AKZ017.
MARINE...Gale Warning for PKZ041>043-051-052.
     Small Craft Advisory for PKZ012-022-033-036-053.




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