Gale Warning 60, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
247 PM AKST Thu Feb 21 2019

.SHORT TERM...Current satellite imagery shows a well defined
frontal band currently pushing inland over Baranof Island. This
will provide the last of significant snowfall accumulations to
areas which are yet to climb above freezing. Highest known
accumulations (as of writing) are just shy of 5 inches in the
Juneau area and over 9 inches in Yakutat. A few winter weather
products remain in effect through the early part of this evening
for another inch or two of expected snowfall out of this system
before precipitation ceases. One thing to look out for this
evening are a few locally higher accumulations associated with the
widespread shower activity currently seen on visible satellite
imagery.

As the surface low continues to track to the southeast
precipitation will subside and northerly outflow winds will
increase. This means a return to strong gales down Lynn Canal and
strong winds for the Skagway area. Additionally by late tomorrow
afternoon conditions become favorable for a mountain wave
development or a "Taku Wind" event in the Juneau area. This has
prompted the issuance of a high wind watch from late Friday
afternoon through Saturday morning for the Downtown Juneau and
Douglas island area, where gusts up to 65 mph are possible.
Lastly, cooler temperatures and clearing skies are expected to
persist through the duration of the outflow pattern.

A fair number of forecast adjustments were made in the short
term. Precipitation type and temperatures were adjusted through
Thursday night to account for the current conditions. Overnight
lows Friday into Saturday morning were cooled associated with the
clearing skies. Lastly winds received a significant upward trend
especially over the north south orientated channels. This has
placed maximum gales into Lynn Canal; however, there is a
potential that storm force winds will develop Friday. Overall
forecast confidence is above average.

.LONG TERM.../Saturday through Thursday as of 10 pm Wednesday/
Long range period will be dominated by a big upper ridge or closed
off upper high over the gulf and interior AK. The developing
blocking pattern could last a week or more. There are still some
model differences on how far W the ridge axis will develop this
weekend and its evolution next week. The biggest difference that
results from the model discrepancies is how much cold air will
move into the area during the weekend into early next week, and
how much moderation might occur later on.

Did make some temp tweaks, mainly raising daytime highs a bit and
lowering nighttime temps in some of the usual cold spots with
decent amount of snowcover enhancing radiational cooling. Will see
some rather large diurnal temp ranges during next week as sun
angle is high enough to warm things somewhat during the day. In
some places, would not be surprised if the diurnal range reaches
30 degrees or more.

Will need to see how close upper ridge/high will be to the area
and how warm lower levels get. A strong subsidence inversion
coupled with potential snow melt maintaining a cool lower
layer could induce low clouds and fog where winds remain light.
Appears best chance of this happening will be during next week
when upper ridge/high will be closest to the area. Overall, forecast
confidence is above average for POPs, near average for temps, and
below average for clouds and winds.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Winter Weather Advisory until 6 PM AKST this evening for AKZ018-
     019-026.
     Winter Storm Warning until 6 PM AKST this evening for AKZ025.
     High Wind Watch from Friday afternoon through Saturday morning
     for AKZ025.
     Winter Weather Advisory until midnight AKST tonight for AKZ029.
     Strong Wind from late tonight through late Friday night for
     AKZ018.
     Winter Weather Advisory until 3 PM AKST this afternoon for
     AKZ017.
MARINE...Gale Warning for PKZ012-013-022-032-041-042.
     Small Craft Advisory for PKZ011-021-031-033-034-036-043-051>053.

&&

JB/RWT

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