Small Craft Advisory 1, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
313 PM AKST Sat Dec 31 2016

.SHORT TERM...Sat imagery and sfc analysis indicate high pressure
building NE across the gulf. A weak perturbation dropping down the
back of the building ridge will bring another shot of mid/hi
clouds to NRN/ERN portions of CWA as it dives south, but fair
weather will persist across SE AK through Sun. This wave is also
contributing to weaker Nly winds than models progged and less
drying as a result. RHs this afternoon across the N gulf coast
and N Ctl panhandle remain in the mid to upper 80%s. Given light
winds over this area already and mostly clear skies tonight,
elected to introduce patchy radiational fog for portions of the
central panhandle and gulf coast tonight. Winds over the N inner
channels also diminishing quickly with only SCA remaining for
N Lynn into this evening. Further S...winds remain breezy through
late tonight with SCA for Clarence Strait through late this
evening. Otherwise, advisories for seas over the outer waters will
persist this evening and begin to subside from NW-SE through Sun
afternoon. Models continue to indicate favorable conditions for a
strong inversion to develop Sun as ridging builds NE. WAA in the
low levels will aid in strengthening the near sfc inversion.
Inherited forecast represented this thinking well and made minor
adjustments to mass fields representing current conditions and
trends.

.LONG TERM...PoP and wind not much of a concern in the extended
range forecast period. Big issue will be extent and duration of
widespread fog that is anticipated. Driving force behind this will
be clear or mostly clear skies under a very strong low level
inversion that will encompass nearly all of the panhandle, the
inner channels, and the eastern Gulf of Alaska. Most difficult
aspect of the long range forecast today has been to accurately
depict the sky while also depicting extensive fog. In the end,
emphasis was placed on depicting more cloud cover over water to
imply a low level marine layer, and less cloud cover over land, to
imply that, above the fog, conditions will be basically sunny.
Take away from all this is that there will mostly likely be
impacts to travel during the upcoming week as a result of
widespread fog.

There will be a very modest warm up Sunday night through Monday
night and then temps will begin to fall once again. However,
conditions not expected to be much below normal for this time of
the year, if at all.

Used an ensemble approach for updates to pressure and wind through
Wednesday. PoP and QPF not a factor. No changes to temps. Overall
confidence is average.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ031-036-041>043.
     Small Craft Advisory due to Seas for PKZ022-051>053.
&&

BC/Fritsch

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