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FXAK67 PAJK 252238

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
238 PM AKDT Sun Jun 25 2017

.SHORT TERM...Through Tue night...Relatively quiet short term
forecast for the panhandle. What is left of a weakening low
is slowly moving eastward through the SE Gulf at the moment
spreading showers and clouds over most of the panhandle. The
exception is Yakutat where offshore flow has caused them to
significantly lose their cloud cover. Winds are generally 15 kt or
less for most areas.

Three features of note for the short term. First is the weak low
in the SE Gulf. That feature will be traversing over the southern
panhandle tonight with continued showers and clouds being the main
effect for the southern 2/3rds of the panhandle. Expected rainfall
will be low. The northern third of the panhandle can expect
improving conditions as offshore flow increases and the low pulls

Second feature of note is the building ridge in the gulf behind
the weakening low. The ridge is looking to be somewhat flat in
nature initially so onshore flow from it will lead to showers
especially in and near the higher elevations of the panhandle
through Tue due to orthographic lifting. Kept at least chance
showers around the area as a result. Also, NW flow in the NE gulf
will lead to the formation of tip jets off the southern parts of
the St. Elias range and Baranof Island Mon evening. Winds at Cross
Sound and Cape Decision are likely to reach 25 or even 30 kt Mon
evening as a result of this. The higher winds will likely last
into Tue morning before the general flow shifts to W or SW turning
off the tip jets. The ridge begins to sharpen up a bit more into
Tue afternoon shutting off the showers.

Feature number three is several shortwaves that are pressing the
ridge against the panhandle on Tue night. The ridge over the
panhandle will keep the rain from these waves confined to the
northern gulf coast. Timing of these short waves is still up in
the air as the models are handling how far east the ridge over the
panhandle is differently. Decided to keep chance pops for the
northern gulf coast and gulf Tue night as a result.

Short range models in decent agreement at least until the short
waves start coming in from the west on Tue night. Decided to stick
with the NAM and GFS for any updates.

.LONG TERM...Wednesday through Sunday...As of 900 PM Sat...
Period begins with upper ridge over SE pushing inland as an upper
trough approaches the W gulf. Models continue to struggle coming
to a consensus on the approaching trough. Although all are in fair
agreement with the main axis, the differences lie in the timing
and strength of the initial short waves ejecting out from the
parent trough and their associated frontal systems. 18Z GFS was a
fast outlier while the 00Z run has slowed slightly coming more in
line with ECMWF on eastward spread of precip with initial
perturbation heading into Wed. Expect most of the panhandle to
begin Wed dry with precip chances expanding from the N gulf coast
early Wed into the entire panhandle late Wed into Thu. Ensembles
continue to indicate fairly large spread with the evolution of
these waves. ECMWF has shown decent run to run consistency
leading to higher confidence in it`s solution over GFS. Inherited
forecast represented this fairly well, but did have a longer dry
period to begin the long range. Increased PoPs/sky cover and
lowered MaxT slightly beyond Thu using ECMWF/GEM/WPC guidance.
Given the high model spread continued trending forecast towards
WPC guidance with active weather continuing through next weekend.


.AJK Watches/Warnings/Advisories...
MARINE...Small Craft Advisory for PKZ012-022-041>043.




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