Area Forecast Discussion
Issued by NWS
FXAK67 PAJK 180045
Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
345 PM AKST Tue Jan 17 2017
.SHORT TERM...The main feature in the next 24 hours will be a gale
force low moving north to off Baranof Island on Wednesday
afternoon. This will lead to another round of precip for the
panhandle and some gusty winds over the southern areas. Warm air
advection with this system will confine most of the frozen precip
to the far northern inner channels and higher elevations. Some
snow may mix in at the onset along the Icy Strait corridor, but
expecting little if any accumulation. A couple inches of snow
is anticipated in the Skagway/Haines area on Wednesday.
Winds will shift northerly this evening over the central and
northern inner channels in advance of the approaching low. A
period of increased cross barrier flow will aid in northeast wind
of 10 to 20 mph developing tonight for downtown Juneau and
Douglas. East-southeast winds over the southern inner channels
will increase by late tonight and peak on Wednesday morning. Have
continued the strong wind headline for the Ketchikan area through
Wednesday morning where gusts of 40 mph are expected. Gusts up to
35 mph can be expected on Prince of Wales island.
Used the 12z NAM for updates to the inherited forecast.
.LONG TERM...Period begins with the low off Baranof Island. Models
continue to diverge on the track of this low, but in fairly good
agreement on the strength. GFS/EC/NAM in decent agreement on the
track while the Canadian remains fastest. Given the good run to
run consistency of the NAM, used it to update pressure Thu. Breezy
conditions early in the long term will shift to the SW gradually ease
through Thu. As this low moves inland, the storm track will
generally be south towards the Pac NW allowing cold air from the
interior to move into the panhandle. Models in fair agreement with
a low/trough moving N into the SE gulf this weekend. This is
where the forecast becomes more difficult. Initial thinking is
that enough cold air will be in place for any precip to begin as
snow. The hindrance to this will be the offshore gradient
inhibiting precip. The upper pattern will transition from trough
along the coast to a low over the interior and off Vancouver
island heading into the weekend. This raises some concern for
potential Taku event Fri night through Sat. Local guidance
indicates favorable conditions late Fri heading into Sat, so
adjusted gridded forecast with gusts to around 40 mph for the Taku
wind area. Extended forecast continues to shift the storm track to
the north early next week with more warm wet southerly flow being
pumped into the area. There is some concern for the potential of
freezing precip Sun into Mon as the initial WAA tries to overtake
cold airmass over the region. Confidence too low attm to include
mention in forecast, but will need to continue monitoring the
potential for this high impact possibility.
Used NAM guidance to adjust forecast Thu, then trended towards WPC
guidance heading into next week.
PUBLIC...Strong Wind from late tonight through Wednesday morning for
MARINE...Gale Warning for PKZ036-041.
Small Craft Advisory for PKZ035-042-043-051-052.
Small Craft Advisory due to Seas for PKZ022-053.
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