Gale Warning 36, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
251 PM AKST Wed Jan 30 2019

.SHORT TERM.../Through Friday night/ Short range forecast still on
track for an arctic air mass to plunge into the panhandle with
some of the coldest temperatures of the winter season so far. But
first, We have some lingering precipitation to deal with. The
front that brought the precip is on its way out of the panhandle
this afternoon, but the SW flow behind it continues to bring some
rain into the area especially as the flow hits the coast
mountains. Precip expected to diminish for all but the extreme
south (front is stalling over Dixon Entrance through Friday)
through the night. Many areas still warm enough for rain and will
stay that way through most of the night. The exceptions are White
Pass and Hyder where temps have stayed cold enough for snow
through accumulations are expected to be light.

By late Tonight and Tomorrow, The arctic air will be making its
initial push into the panhandle and temperatures will generally be
on a downward trend for the next 24 to 48 hours (did lower some
highs and lows 5 to 8 degrees for Thu night into Fri night
compared to the previous forecast). Daytime highs will be in the
20s for Fri, and overnight lows will be in the teens and 20s Thu
night and single digits to teens for Fri night. Previous forecasts
have also suggested that their would be a chance for an
overrunning snow event for some areas of the northern and central
panhandle Thu into Fri as this cold air advances, but that is
becoming increasingly unlikely. recent guidance is weakening the
low in the NE gulf much faster so mid level onshore flow is
expected to be weaker to non-existent. There may still be some
residual rain/snow Thu morning for the north, but it should mostly
be gone by afternoon. As such Pops and QPF have been noticeably
lowered through the period.

With the arctic push, Outflow winds will become a problem again
starting as early as Thu. Expect at least gale force winds, if not
stronger, in Lynn Canal by Thu night with equivalent winds blowing
out of Cross Sound, the passes near Yakutat and other similar
outflow areas. The Taku winds will also be making a return for
Downtown Juneau and Douglas with gusts increasing to around 50
mph by Fri night. Combined with the expected cold temps, wind
chills will become very low particularly along the Highways, and
freezing spray will show up in many marine areas as we get more
toward Fri and Sat.

Model agreement is still rather good for the arctic outbreak in
general and is getting better for the details. Main changes were
drying out the panhandle for Thu afternoon and onward, lowering
some temperatures a bit more, and adding details to the outflow
winds. Favored using the Nam and Gfs for updates.

.LONG TERM.../Friday through Wednesday as of 10 pm Tuesday/
Models falling more in line initially however mid level blocking
type pattern still causing problems beyond the weekend. For Friday
mid level trough over the N Panhandle drops south with high
pressure ridge over the central gulf extending into the far north
AK interior. The mid level waves shift to the east Sunday with
potential low forming over the NE AK gulf. GFS more progressive
with this low. This pattern looks to continue through the long
range but little in way of model resolution.

At the surface arctic air will remain in place with some slight
warming into next week. Pressure gradient will ease as surface
low drops south so outflow winds should start to subside into
Saturday relying on thermal gradient as forcing mechanism.
Lowered pops for Fri as waves drop south, so even with the cold
air central and northern panhandle not likely to get much more
snow but southern panhandle could get a few additional inches on
Fri. Next potential for snow is Monday, but as of now it depends
on which model solution you pick and where it places the next low.
Forecast confidence is average at the start then drops by the
start of next week.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Strong Wind Thursday afternoon for AKZ018.
MARINE...Gale Warning for PKZ012-013.
     Small Craft Advisory for PKZ022-031>034-043-051.
     Small Craft Advisory due to Seas for PKZ041-042.

&&

EAL/PRB

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