Gale Warning 202, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
218 PM AKDT Fri Oct 12 2018

.SHORT TERM.../ Through Sunday / A developing atmospheric river
is moving into the north central gulf coast region Friday night as
the lead lower pressure system moves quickly into the Central Gulf
Coast area. Strong winds and heavy rains are accompanying the
low. The moisture stream extends nearly to the Hawaiian Islands. A
secondary wave further back on the frontal band will run along
the front to move inland Saturday afternoon and a third for the
northern panhandle early sunday. The frontal band will shift east
to be over the northern- central half of the panhandle Sunday
before the developing wave pulls the frontal band back north to
the Yakutat area Sunday night. A tight gradient on the east side
of the front will see strong south winds helping to push some
warmer air northward the will spread slightly into the southern
panhandle. Do not expect much warming only a few degrees.

Southern panhandle not expecting much of the frontal band as it
stalls north of Frederick Sound. So while the northern panhandle
is receiving 3 to 5 inches, the southern will likely see 3 to 5
tenths of an inch.

Gusty wind on the coastal area near the frontal band and less
gusty across the inner channels. Have gusts 40 mph or so
forecasted from Cross Sound north to the Yakutat area on
Saturday. Have kept the strong wind headline and added the Cross
Sound area to it. Northern inner channels will likely be gusting
to 35 mph.

.LONG TERM.../Sunday through Friday, As of 10 PM Thursday/...An
active period of wet and windy weather will persist through the
week. Sunday will begin with an atmospheric river impacting the
northern Panhandle. This will produce widespread heavy rain over
the northern Panhandle. The heavy rain band will likely meander
through the day pushing south through the morning hours and then
drifting back to the northwest through the late afternoon and
evening. While the southern Panhandle will see some rain on Sunday
the heaviest rates will likely stay north of Sumner Strait.
Monday a surface low near the Bering Sea will send another front
northward; this will act to renew the heavy rainfall rates along
the northeast Gulf coast. The rain will spread east through the
day; however, most of the long lasting heavy rainfall will impact
the northern Panhandle, especially, the NE Gulf Coast. Between
late Wednesday and Thursday a brief dry period may occur before
the next surface low tracks into the Gulf sometime Thursday. One
thing to note is with the tropical origins of these systems
temperatures will stay seasonably warm, so low elevation snowfall
will not be a concern with snow levels remaining between
4000-7000ft.

Besides the heavy rainfall, winds will be a concern over the Gulf
with a large band of 25-30 kt winds expected Sunday From
Fairweather to Cape Decision. The same will be true for the inner
channels with 25 kt winds expected in portions Lynn Canal, Chatham
Strait, Stephens Passage, Frederick Sound, and Cross Sound. The
inner channel winds may see a few periods of stronger winds as the
system meanders S and N. Winds in the inner Channels will diminish
between late Sunday and Monday before increasing Monday morning
once again as the next front pushes N. The system later this week
looks like it will carry a band of gale force winds into the Gulf;
however, confidence is not high enough to place a definitive band
in the forecast yet.

Overall no major changes to the extended forecast were made. Winds
in the inner channels were increase on both Sunday and Monday.
Also the precipitation forecast was adjusted to add greater
detail to the location of the atmospheric rivers heaviest rainfall
rates between Sunday and Monday. Forecast confidence is above
average through Monday, average Tuesday and Wednesday, and below
average Thursday and beyond.

&&

.AVIATION...Few hazards this evening with only some lower clouds
in the northern panhandle and patchy fog stubbornly holding on
through the afternoon. Ceilings and visibilities should crash
down to IFR or low MFVR in the Yakutat area tonight in the
moderate to heavy rain and then will see these conditions slowly
move to the northern panhandle by Saturday. The second hazard,
more for tonight and Saturday, will be LLWS with a strong low
level jet with the Atmospheric River along the frontal band.

&&

.MARINE...A more typical fall storm is finally moving across the
gulf and into the northeast gulf coast area late Friday and early
Saturday. Winds ahead of the front increasing 35 to 45 kt with a
couple small pockets of 50 kt storm force winds. Gales for nearly
the rest of the outer coastal waters. Small craft wind of 25 to
30 for much of the inner channels as the front moves toward the
northern panhandle.

&&

.HYDROLOGY...Wet for the northern panhandle and NE Gulf coast
areas for the next several days to to an atmospheric river
developing. 3 to 5 inches through Sunday and higher amounts in
the coastal windward terrain. Rivers and streams expected to rise
significantly, however do not expect flooding on them. The smaller
quicker reaction streams might have an issued depending on the
rain rates experienced. South of Sumner Strait the flow pattern
unfortunately protects the area and less than 3/4 inch is expected
through the weekend.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Strong Wind Saturday afternoon for AKZ022.
     Strong Wind from Saturday morning through Saturday afternoon for
     AKZ017.
MARINE...Storm Warning for PKZ052.
     Gale Warning for PKZ043-051.
     Small Craft Advisory for PKZ011>013-021-022-031-032-041-042-053.

&&

Bezenek/JB

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