Heavy Freezing Spray Warning 1, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
309 PM AKST Mon Jan 25 2021

.SHORT TERM.../Through Tuesday night/ Today brought a mix of
clouds and sun across the panhandle with more clouds in the north
as a weak shorwave is passing through. TAFs have been a challenge,
specifically pinpointing when and where the various cloud decks
will make their appearance. High clouds over the north will likely
limit fog development, while the southern zones have fog
development potential from Monday evening through early Tuesday
morning. Drizzle and flurries were removed from the Monday night
forecast due to the limited moisture with this feature.

Winds will increase dramatically into Tuesday as the pressure
gradient tightens between a high in Canada and a low in the SW
gulf. Expect a strong northerly gale to develop in Lynn Canal
while small crafts develop in the Central and Southern Inner
Channels. Higher gusts are likely out of interior passes and in
typical outflow areas. Strong winds with gusts to 50 mph possible
in Skagway and along the Klondike Highway during this timeframe.
Mountain Wave guidance for downtown Juneau keeps conditions poor
for Taku winds through mid week with weak cross barrier flow,
around 40 kt, and a lack of a critical layer. Gusts to 50 mph are
still possible around downtown Juneau due to gap flow winds from
the tight pressure gradient; however do not expect a mountain wave
to develop at this time. Temperatures will also cool as the
outflow event progesses.

Overall forecast confidence is at or above average for the short
term. Lowest confidence remains in the fog and low cloud
development later this evening.

.LONG TERM.../Wednesday through Sunday/ As of 10pm Sunday. The
"cold air outbreak" will be reaching it's peak mid-week at the
beginning of the extended forecast period. High temperatures in
the teens to upper 20s will be widespread across the panhandle
while low temperatures will generally be in the teens to single
digits. A bigger temperature difference of 10+ degrees is likely
between interior valley locations and windy spots (ie. the
Mendenhall Valley and downtown Juneau). Strong high pressure
over the Yukon and an inverted trough over the inside waters will
cause predominately N-NE outflow winds through the inside waters,
reaching gale force for Northern Lynn Canal. As a result, freezing
spray remains in forecast and was even expanded to more marine
waters. Overall, this is a dry pattern for SE Alaska, so have
kept the POP forecast low.

The Yukon high pressure will shift down into northern B.C.
Wednesday night through Thursday. This will shift the best outflow
to be more out of the eastern interior passes, including potential
for Taku winds. Meanwhile, a low pressure system will move into
the northern gulf from the west Thursday night, increasing said
E-W pressure gradient. A front extending outward from the low
creates the potential for snow along the outer coast as the low
tracks slowly SE Friday into Saturday. Latest models, and their
previous runs, have had more differences with the position and
subsequent track of this low, so have only made minor changes to
this portion of the forecast. But more often than not, the high
pressure and dry air already in place wins out, limiting how far
inland the snow can reach - and may end up just causing increased
clouds. Once the low shifts SE, the cold/dry/northerly pattern
continues.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Strong Wind from Tuesday morning through Tuesday afternoon for
     AKZ025.
     Strong Wind from Tuesday morning through Tuesday afternoon for
     AKZ018-019.
MARINE...Gale Warning for PKZ012-013.
     Small Craft Advisory for PKZ021-022-031>034-041>043-051-052.

&&

BFL/Ferrin

Visit us at http://www.weather.gov/Juneau