Weather Service Report

FXAK67 PAJK 221322

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
522 AM AKDT SAT OCT 22 2016

.SHORT TERM...Somewhat quiet forecast for the next 24 hours as we
transition from widespread showers and southerly flow to drier
weather with northerly outflow starting to develop. Currently the
low that brought the wind to the southern panhandle yesterday is
still in the gulf though weaker then it was. As of 5 am it is
positioned just offshore of Baranof Island and is expected to
continue to slowly weaken through the day as it drifts to the
west. Into Sat night an upper trough will be starting to transits
over the area bringing cold surface high pressure into the Yukon
as it comes. Overall flow will switch to more offshore Sat night
and will allow the panhandle to start to dry out.

Precipitation remains rather convective in nature based on
satellite and radar imagery. However it is not as active as it was
yesterday. There has been a distinct lack of lightning overnight,
however with convective indexes still showing a rather unstable
atmosphere over the SE gulf through the day decided to keep a
slight chance of thunder going in that area. These showers will
gradually diminish in coverage through the next 24 hours
eventually drying up by late Sat night as outflow winds begin to
develop across the north.

Winds have been slowly coming down as the low weakens. Some
breezy conditions remain in some areas but most are 20 kt or less
at this point. The exceptions are in the NE gulf and Cross Sound
where a combo of synoptic flow around the weakening low and
increasing surface pressure in the Yukon are creating ne winds of
25 to 30 kt at the moment. Winds in the southern and central inner
channels will remain rather low through Sat night, but winds will
be increasing across the northern inner channels. The building
cold surface high in the Yukon will start to cause some outflow
winds to develop in the usual areas. Lynn Canal in particular will
likely reach 25 to 30 kt Sat night as a result.

Short range models are in decent agreement with few major
differences noted. NAM and the various Hi-res models were used for
updates today to get some better details in the developing outflow
winds. Otherwise most changes were limited to local effects.

.LONG TERM...Overall mostly dry weather pattern with increasing
outflow winds continue for the first part of the week as upper
level ridge becomes established over the central AK gulf with
inverted trough extending northward over the panhandle and eastern
gulf. At the surface, a low forming off the western CONUS coast
has been most variable feature. Short waves are shown to rotate
around the main low center moving over the southern panhandle and
then into the southeast gulf. Latest model runs, while showing a
fair amount of spread, are moving in more precip bands and
tracking them bit further north. Have bumped up pops to chance
levels with the formation of these features for locations south
of Frederick Sound while keeping the rest of the panhandle dry
due to offshore flow. The main low is expected to weaken and
dissipate mid to late in the week as next frontal boundary moves
across the AK gulf. Potential cyclogenesis along this front with
a closed low forming in the central gulf may have combination of
delaying precip reaching the panhandle and keeping it mostly over
the southern half. Still too early to put much confidence on this
newer solution.

Pressure gradients between areas of high pressure over the Yukon
and AK gulf and the inverted trough over the panhandle will
produce increasing outflow winds. Localized small craft winds over
the AK gulf from outflow areas. With surface waves moving over
the SE gulf getting some higher winds over PKZ041, and 042.
Northern inner channel winds reaching gales with max small crafts
over the central inner channels. Strongest overland winds will be
in typical areas such as Skagway and the downtown Juneau/Douglas
areas. Latest NAM model soundings starting 00z Mon showing good
set up for Taku wind event with cross barrier flow, inversion and
critical level. Started process of increasing winds there.

Highs will be in the mid to upper 40s as cold 850 mb temps move in.
Overnight lows will be highly variable with wind sheltered areas
dropping into the 20s but temps in the upper 30s to low 40s where
there are high downslope winds.

For overall synoptic pattern updated with 00z ECMWF/GFS to day 3
then left inherited WPC for rest of time frame. Started to blend
more high res model winds where available to get the increased
localized outflow and higher elevation winds. Forecast confidence
is average.


.AJK Watches/Warnings/Advisories...
MARINE...Small Craft Advisory for PKZ012-013-022-036-041-043-051. 
     Small Craft Advisory due to Seas for PKZ042-052. 



Visit us at

Return to Home page

Western Regional Climate Center,