Small Craft Advisory 530, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
206 PM AKST Sun Nov 7 2021

.SHORT TERM.../Sunday Evening through Tuesday Night/...Through
Sunday night, a relatively weak low in the southeast Gulf will
bring some isolated to scattered light shower activity to the
southern Panhandle. It is possible that the higher elevations on
the road system on Prince of Wales Island could get some light
snow accumulations up to around one inch Sunday night. Places
whose temperatures are moderated by being near sea level such as
Hydaburg, Craig, Klawock, and Edna Bay will stay warm enough to
only see scattered rain showers.

For the rest of the Panhandle, a ridge of high pressure up at
500mb look to give the central and northern Panhandle subjectively
nice weather through Sunday night with dry conditions and clear
to partly cloudy skies. Relatively non-impactful sustained land
winds will be felt over the Panhandle, generally staying less than
20 mph through Sunday night.

A weak front will move from south to north over the Panhandle on
Monday, bringing only very slight chances for shower activity.
The likelihood that most areas will remain dry on Monday is high.
Primarily, people will see increased cloudiness and marginally
increased wind magnitudes according to ECMWF and GFS ensemble
average model output.

Unlike Saturday night into Sunday morning, increased wind speeds
of at least 10 mph, causing convective mixing of the boundary-
layer, will keep the threat of any widespread persistent dense fog
at bay for the area, tonight, and for the remainder of the short-
term forecast period.

On Monday night, a much stronger system will move well to the
south of the southeast Gulf and Panhandle. The main impactful
changes for the region will be increased marine winds up to
borderline small craft and Gale over southeast Gulf outside waters
and over the Inner Channel waters. This will be due to the
increased pressure gradient between the aforementioned strong low
and established higher pressure over the Canadian Yukon region.
This will bring northerly outflow winds over the northern Inner
Channels where the pressure gradient will be the tightest.

Since chances remain quite low for any appreciable precipitation
over the Panhandle, temperatures will remain relatively non-
impactful through the short-term forecast period. Low
temperatures will primarily be in the 20s to 30s over the
Panhandle from north to south, respectively. Highs will generally
be in the 30s to 40s over the region.

Overall, forecast confidence remains above average, due to good
model agreement. Not many significant changes had to be made to
the forecast that we inherited to keep the forecast on-track.

.LONG TERM.../Tuesday through Sunday as of 10 PM Saturday/ Start
of the long term continues to hint at below-normal temperatures,
above-normal precipitation in the late long term, and chances
that whoever does not see their first snowfall at the start of the
short term, will likely see snow in the long term.

The surface low mentioned in the short term meanders south of the
panhandle, resulting in a very slight chance of precipitation in
the southern portion of Prince of Wales, but leaving the remainder
of the panhandle with offshore flow and dry weather through mid-
week. N/S pressure gradients will be strong, resulting in small
craft advisory potential for N/S oriented channels, especially
Northern Lynn Canal.

Models are still in agreement with the main system, which will
approach the panhandle sometime on Thursday/Friday with heavy
rainfall rates that may start as snow in the northern half of the
panhandle. This increase in precipitation is signaled in the
climate predication centers outlook, ensemble tables, and the
Alaska RFC. Winds will pick up in the Gulf first and then as the
low approaches the panhandle a strong W/E pressure gradient
will increase the chances of small crafts to those oriented
channels.

Continued to use the WPC and blended with GFS/NAM where
appropriate. Increasing confidence of a drying trend mid-week and
an impactful storm at the end of the week. Main changes tonight
included decreasing the probability of precipitation for Tuesday
and thus removing the snowfall, adding in the winds/precipitation
for the late week system, adding possibility of snowfall at the
start of the end of week system.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ012-022-041>043.

&&

JLC/KRT

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