Area Forecast Discussion
Issued by NWS
FXAK67 PAJK 202307
Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
307 PM AKDT THU OCT 20 2016
.SHORT TERM...A frontal band moving across the panhandle from
south to north today is causing scattered to numerous showers.
The band is currently over the south/central panhandle and will
move northward with showers in Juneau this evening and up to
Haines in the late evening. Behind the frontal band is a break in
the precip and clouds and some patchy fog could develop through
the night, again from south to north.
The main weather feature for the next 24hrs is a gale force low
that is approaching Dixon Entrance tonight. Clouds and showers
will move back into the southern outer coast by midnight then
spread north through Friday morning. Over the gulf, a slight
chance of thunderstorms remain in the forecast near the low
center. Winds assoc with the low will increase to gale force
along the southern outside waters and up through Clarence Strait
overnight. Adjacent land areas including Hydaburg and Annette
Island/Ketchikan can expect wind gusts of 40-45mph late tonight
through Friday with a peak Friday morning. The low to the south
will cause winds through the inner channels to become NELY, if
they aren`t already, and increase 15-25kt. Cross Sound will see
some enhancement with 30kt winds developing by early morning.
Models were in good agreement through the short-term period. For
minor adjustments that were made, used an ensemble approach with
an emphasis on the NAM. Forecast confidence is above average.
.LONG TERM...Big story in the extended range is a pattern change
late in the weekend and early next week. This will be caused by a
significant storm system moving into the Bering which will amplify
a ridge over the central and eastern gulf. The resultant synoptic
pattern will promote clearing skies and increasing northerly
outflow wind for Southeast Alaska. Still too far out to get into
details but a period of small craft to gale force winds is likely
for the northern and central inner channels. The usual outflow
areas such as Skagway and downtown Juneau/Douglas can expect a
period of gusty winds as well. Significant cold air advection will
occur with 850 mb temperatures falling to between -4 and -8 C
over the northern panhandle. Thus expect high temperatures in the
low 40s during this time frame. Low temperatures will be variable
due to outflow winds but sheltered locations will fall into the
Model solutions diverge rapidly with the breakdown of this ridge
by mid to late next week but the general consensus is a return to
onshore flow with increased cloud cover and precipitation chances.
Used a blend of the 12z ECWMF/GFS through day 4 then the 12z WPC
PUBLIC...STRONG WIND from 10 PM AKDT this evening through Friday
afternoon for AKZ027.
STRONG WIND from 1 AM AKDT Friday through Friday afternoon for
MARINE...Gale Warning for PKZ036-041.
Small Craft Advisory for PKZ022-033>035-042-043-051.
Small Craft Advisory due to Seas for PKZ052-053.
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