Area Forecast Discussion
Issued by NWS
FXAK67 PAJK 011448
Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
548 AM AKST Wed Mar 1 2017
.SHORT TERM...Low pressure system over the northern AK gulf will
begin to track to the west while weakening. Associated frontal
boundary moving over the central and northern panhandle along
a trough extending from the gulf low. Another strong low will
move up from the N Pacific tonight and into the southern AK gulf.
Gale force winds over the northern AK gulf this morning and
strong outflow winds from Cross Sound northward will begin to
diminish as the low pulls west. Winds will increase again this
evening as the new low progresses northward. Tightening northerly
gradient will again increase winds to gale force to near storm
force for the northern inner channels. Strong winds along the
panhandle coast and from outflow areas will also develop.
Moderate snow continued over the northern half of the panhandle
this morning with snow showers over the southern half. Warm
saturated layer moving over colder surface air keeping over
running snow event going through the late evening. Heaviest snow
fall will be over the central panhandle. As next low moves up
another round of heavy snow will start late tonight. With more
southerly flow the next system has more moisture and higher QPF
amounts. Model soundings show a well formed nose of warm moist air
at 850 mb with the next front. The southern panhandle will begin
to get more rain and thus lower snow accumulations as surface
temps warm. As long as surface temps for the central and northern
panhandle remain in the 20`s, which is expected, this next system
could produce a much more robust over running event and produce
higher snow amounts.
Early on models were in fair agreement with timing of the exiting
system. For the next low model spread increases with the GFS the
fastest and ECMWF/Canadian/NAM bit more in line but slower than
previous model runs. For now keeping winter weather hazard
timings as is since new model runs were moving the next low a bit
slower. Went with a Canadian/NAM blend which shifted some timing
of winds increasing over the southern gulf later tonight. Lots of
uncertainty with snow accumulations especially over the southern
.LONG TERM...More heavy snow expected for Thursday for locations
north of Frederick Sound and south of Cape Fairweather. Snow
begins to taper off after that, but remains in the forecast
through Friday night.
The strong low mentioned above that enters the eastern gulf late
tonight is forecast to be storm force strength. Current forecast
track takes it close to Sitka by Thursday morning. Strong wind
gusts very likely with wind gusts in excess of 55 mph not out of
the question yet. Very strong high pressure over the Yukon at the
same time will result in a very strong northerly pressure
gradient with wind gusts to 55 mph currently forecast for the
Skagway area and 60 kt storm force winds over northern Lynn Canal
Wednesday night through Friday afternoon. Pressure pattern and
gradient also favors storm force winds out of Cross Sound on
Updates tonight limited to the Friday/Friday night time frame and
the Canadian NH was used for pressure and wind. PoP and QPF from
the 00Z GFS blended with the 06Z SREF and Canadian. No changes to
temperatures. Overall forecast confidence is average.
PUBLIC...Winter Storm Warning until 9 AM AKST this morning for AKZ023-026.
Winter Weather Advisory until 6 AM AKST early this morning for
Winter Weather Advisory until 9 AM AKST this morning for AKZ024.
Winter Storm Warning until midnight AKST tonight for AKZ020>022-
Strong Wind until noon AKST today for AKZ022.
Strong Wind late tonight for AKZ018-022-023.
Strong Wind until 9 AM AKST this morning for AKZ018.
Strong Wind from noon AKST today through this afternoon for
Strong Wind through this evening for AKZ017.
MARINE...Storm Warning for PKZ022.
Gale Warning for PKZ011>013-021-031-033>036-041>043-051-053.
Small Craft Advisory for PKZ032-052.
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