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FXAK67 PAJK 171347
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
547 AM AKDT Wed Jul 17 2024

.SHORT TERM.../through Wednesday night/...The next surge of
moderate to heavy rain has begun. Still expecting upwards of 2 to
3 inches of rain over 24 hours for areas along Icy Strait
(including Gustavus, Hoonah, and Juneau), and south to near
Petersburg. Much lighter amounts, around an inch or less,
elsewhere.

After the center of low pressure moves out of the area, SE AK will
transition to the backside of the low which will push the rain
east and southeast. As this happens, rain rates will decrease,
cloud cover will decrease, and wind speeds will decrease.

.LONG TERM.../Thursday through Tuesday/...
Overview: A relatively quite weather period is likely for SE AK. A
number of breaks are in the mid to long range, not exactly dry but
not the intense rainfall and stronger winds we have been seeing.

Mid level low with trough extended into the AK Gulf moves eastward
then drops to the south into the weekend. As part of a blocking
pattern, to the west a ridge then another low, this mid level
pattern will shift in position somewhat by likely not change until
late next week. For Thursday remnants of the Wednesday front will be
over the southern region keeping rain going. Points north of
Frederick Sound not have higher chances of rain breaks that day.
With the 500 mb low in place flow pattern will move a low extending
from a deeper system over the far SW Gulf northward into the SE Gulf
by Friday. For now winds around the low expected to be in the 20 kt
range with lighter winds to the north. Light to moderate rainfall
amounts move in with the system with most models keeping precip over
the south with diminishing rates as the low moves northward. GFS
tracks furthest north with highest winds and pop. By late Saturday
this low will have dissipated, but the main low remains in place
into next week and thus can keep pushing precip bands over the
panhandle. The southerly flow and weather breaks will let day time
highs pick back up into the upper 60s to low 70s. With the run to
run inconsistencies seen that past few days not fully jumping on any
one solution so overall keeping with SE AK climatology: mostly
cloudy chance of rain.

&&

.AVIATION...Conditions deteriorate through the morning hours on
Wednesday as another system arrives. Anticipate widespread IFR
and LIFR conditions arriving, along with LLWS for some locations.
Gusty surface winds are expected. Conditions will begin to improve
during the afternoon and evening hours, especially across the
Northern panhandle, as the wave departs.

&&

.MARINE...Main marine concerns are centered around the quick
moving low that will move through the panhandle today. Early this
morning, wind speeds ahead of the low are around 5 to 15 knots out
of a general northerly direction. But as the low moves north,
these winds will quickly shift to the south and pick up speeds to
around 15 to 25 knots.

The timing of that switch will be closely watched but for now,
expecting marine zones south of Icy Strait to see the switch this
morning. Areas along and north of Icy Strait look to see the
switch late this morning to early afternoon.

After the low clears out, wind speeds will decrease, to around 5
to 10 knots, this evening into overnight from south to north. The
lighter wind speeds will last into Thursday.

&&

.HYDROLOGY...The forecasted rain amounts of 1.5 to 3 inches for
the area today and the saturated soils will cause rivers and
streams to rise rapidly. There is good ensemble agreement on this
heavy rain event with 50 to 70% chance the area will see the
forecasted rain amounts and these values are very anomalous for
this time of year. With that said there are flood advisories out
for the Chilkat River area, Taiya River area and the Mendenhall
valley area for minor flooding through Thursday morning. Flooding
is expected to develop through Wednesday afternoon and persist
into the evening time frame. A flood watch is still in affect for
the full Juneau borough as other non gauge rivers/streams that may
flow out of their banks. For other areas outside of the flood
advisories, there is a special weather statement out for
significant river rises but not flood is expected for those areas.
Some of the large rivers may stay above flood stage longer due to
the lag in draining all the rainfall runoff and melted ice.



&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Flood Watch through late tonight for AKZ325.
MARINE...Small Craft Advisory for PKZ011>013-021-022-031>036-641-642-661-
     662.

&&

$$

SHORT TERM...GJS
LONG TERM....PRB
AVIATION...GFS
MARINE...GJS
HYDROLOGY...GJS

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