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FXAK67 PAJK 232318
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
318 PM AKDT SAT JUL 23 2016

.SHORT TERM...A strong low pressure system over the NE gulf has
been causing 25-35kt winds across much of the region today. The
associated front has pushed through Gustavus and Hoonah as of 2pm,
indicated by the wind shift to W-SW along with some breaks in the
clouds seen with visible imagery. A wind shift is also expected in
Juneau/Auke Bay area but should be fairly short-lived then go back
to the S-SE that`s been occurring all day. The low center will
continue east to be just off of Cross Sound tonight. As the low
shifts to this position winds should shift back to the east
through Icy Strait and Cross Sound, however low placement/timing
may vary. Tightest pressure gradients are on the south side of
the low where SW winds off 25-35kt will continue overnight and
impact Baranof Island.

A second wrap with peak vorticity near the low center will move
onshore tonight. This looks to cause the heaviest showers over the
central panhandle along with more gusty winds. See the hydro
section below for more on that. The strong onshore flow aloft will
continue through the night and enhance the precip further along
west facing mountain slopes. No lightning strikes have been
reported today, but have kept the slight chance in the forecast
for early this evening near the low center since it is still
strengthening.

The low center will dissipate by Sunday morning but the southerly
pressure gradient across the inside waters will remain strong
enough for small craft advisories to remain most of the day in
places like Stephens Passage and Lynn Canal. Westerly onshore
flow will prevail through Sunday but weaker than tonight. This
will keep showers in the forecast for the much of the area.

.LONG TERM...Southwesterly flow aloft is forecast to persist
throughout much of the upcoming work week, which will favor wet
conditions across the region. Model guidance shows that the
heaviest rain will initially become confined to AKZ017 Monday and
Monday night as weak shortwave ridging develops over the
panhandle. However, rain will return to the entire panhandle going
into Tuesday as a shortwave trough breaks down the previously
mentioned ridge. Thereafter, an upper low will persist over the
western gulf through midweek, maintaining moist onshore flow
across SERN AK through at least Friday. At the surface, a ridge of
high pressure is forecast to be situated over the panhandle during
most of the week, which will favor southerly low-level flow.

The previous forecast was in good shape, no major deviations were
necessary. Minor updates to inherited grids were made using GFS,
ECMWF, and WPC guidance.

&&

.HYDROLOGY...The Taiya River near Skagway has gone over minor
flood stage this afternoon. It is expected to peak late tonight
then fall below flood stage Sunday morning as rainfall rates will
have diminished. Juneau area rivers showed a sharp rise with the
heavy rain this morning. Expect another sharp rise with heavy
showers this evening with 2nd wrap. This could bring them up near
bankfull, but once the heavy showers move out they will fall
rapidly again.

The Salmon River near Hyder crested this morning with a peak of
27.55 feet after a glacier dam release. The river will continue to
fall over the next 2 days despite rainfall from the current front.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...STRONG WIND until 4 PM AKDT this afternoon for AKZ025.
MARINE...Small Craft Advisory for PKZ012-013-021-022-031>036-041>043-051-
     052.
&&

$$

Ferrin/Garner

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