Small Craft Advisory 732, NWS Juneau, AK

Southeast Alaska Forecast Discussion...CORRECTED
National Weather Service Juneau AK
1016 PM AKST Tue Nov 22 2016

.SHORT TERM...Satellite imagery this afternoon showing two
surface lows under a broad upper level low over the AK gulf. One
low in the western gulf will continue to progress westward while
weakening. The second low, off the coast of Haida Gwaii, will
show some eastward progression, but mainly weaken in place. For
Wednesday another surface low drops in from the western gulf on a
southeasterly track heading again for the Haida Gwaii coast.

Frontal band tracked over the panhandle overnight with mid level
short waves continuing to move northward behind the main front.
Warming trend began after frontal passage with some sharp
increases in temperatures. Yakutat airport had an 18 degree rise
when the front moved over, winds shifted to the southeast and
increased. Expect the general warming trend to continue with many
locations overnight temps remaining steady or showing a slight
increase. While northerly and outflow winds will diminish as the
low to the south weakens these may still be enough for some temps
to show little rise.

Snow showers for locations north of Frederick Sound today
produced low visibilities but not much accumulations. Amounts
ranged from 1 to almost 2 inches with very fine light snow grains.
Locations to the south where temps warmed to the 40s reported only
rain showers. As the next bands associated with the advancing mid
level short waves move over this evening expect more rain to begin
to mix in with the scattered snow showers. At most only another
inch of snow accumulation is expected.

Gulf winds will remain at small craft levels under low level 850
mb jet along the coast. Inside water wind lull begins the
afternoon but as next surface low moves in pressure gradient
increases with northerly small craft winds developing for most of
the inner channels Wednesday.

Models in good agreement for synoptic pattern. NAM was tracking
the short waves fairly well, but none of the higher res models
initialized winds accurately today. Overall left forecast as is
with a slight adjustment with NAM on outside waters. Forecast
confidence is average.

.LONG TERM...While a low rests south of the Panhandle Wednesday
night and Thursday, a related front may quickly swing up from
Dixon Entrance Wednesday to allow some wind to develop across
Prince of Wales Island. Ordinarily a low to the south means drier
weather for points north of Frederick Sound. Currently, we have
kept the scattered snow/rain showers here, as a consensus has not
been reached on how dry things will become. We also added some fog
as gradients should begin to fall through Thursday morning,
especially for the central Panhandle. If stronger offshore flow
does develop we look for skies to begin to clear.

The main changes to the long-range forecast were reserved for the
weekend into next week. Models have come together fairly nicely in
representing a front moving into the eastern gulf. Thus we have
increased winds and seas...especially for Sunday as westerlies
behind the front will reach gale force in the central gulf waters.
Likewise, with increasing southerlies associated with a low level
jet ahead of the system, we raised temperatures Saturday night
into early next week in order to mix rain with the snow or to
allow an all-out transition in some areas. Currently, models are
not signaling a high confidence rain event as snow levels will be
around 1000 feet across the central Panhandle, give or take a 1000
feet on each end, but we at least wanted to hedge. Still there is
the possibility of advisory level snow amounts Sunday morning
before precipitation potentially mixes with or changes to rain.

We used NAM Wednesday night into Thursday before transitioning to
GFS/EC/WPC into the weekend. WPC used for next week.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ012-013-022-031>036-041>043-051-052.
     Small Craft Advisory due to Seas for PKZ053.
&&

PRB/JWA

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