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FXAK67 PAJK 151435
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
535 AM AKST Mon Jan 15 2018

.SHORT TERM.../Through Tuesday night/ Rather difficult forecast
for the next 48 hours as a series of three fronts move through the
area. A very weak cool front moved through last night and is now
shearing apart over the northern panhandle. This is what brought
the brief period of light rain and gusty winds last night. The
winds also caused wild swings in temperatures overnight as a combo
of localized downsloping, and terrain blocking made some areas
warmer then others. Some of these swings were by as much as 11
degrees in less then an hour in both directions.

unseasonably warm temps continue for today and tonight as
southerly flow persists, but are not expected to be as warm as
yesterday. The weak front that went through last night brought in
some slightly cooler air, but another warm front will be moving
north through the panhandle mid day. The warm air mass behind it
is not as warm as yesterday but with 850 mb temps getting up to 7
above zero C it will still be much warmer then normal. As a
result, highs for today are still expected to be in the mid and
upper 50s for many areas with some 60s possible for the southern
panhandle. Some places have already hit their highs for the day as
temperatures were rather warm overnight. A stronger cold front
moving through early Tue morning will bring cooler (highs in the
40s Tue, lows in the 30s Tue night) but still above normal
temperatures to the panhandle.

The series of fronts will also be bringing more periods of gusty
winds (and wind shear for aviation concerns) and rain. Winds and
any lingering light rain will diminish this morning as last
night`s front moves north. The warm front midday will not have
much wind associated with it however there will be some bands of
rain keeping pops in the likely category for most of the day. One
more break in winds and precip this evening before the cold front
moves in for early Tue morning. More gale force winds expected
out in the gulf with this cold front while gusty winds return for
the panhandle. Ptype expected to be rain for all areas except
White Pass and Hyder where temps will cold enough for at least a
mix of snow at times.

Changes to the forecast mainly centered around winds and
temperatures using GFS and Nam for guidance. Winds mainly focused
on local effects and the higher winds with frontal passages. High
temperatures for today were increased up to 5 to 10 degrees over
the previous forecast with lower increases for tonight`s lows and
Tuesday`s highs. Temperature guidance was way too low for many
areas today with current obs already surpassing highs suggested by
the models for some areas.

.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
features.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Strong Wind until 6 AM AKST early this morning for AKZ023.
     Strong Wind until noon AKST today for AKZ017.
MARINE...Gale Warning for PKZ041>043-051>053.
     Small Craft Advisory for PKZ012-021-022-033-036.

&&

$$

EAL/Voveris

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