Small Craft Advisory 27, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
533 AM AKST Sun Jan 15 2017

.SHORT TERM...Satellite imagery this morning showing shower
remnants of trough that moved over the panhandle Saturday night
into early Sunday morning. High pressure ridge crosses over the
panhandle today before the next system moves in. Over the western
gulf a strong low is tracking northeast towards Prince William
Sound, following a similar track to the previous systems. Strong winds
over the northern panhandle this morning will drop off as the
trough and panhandle ridge move east and pressure gradient becomes
parallel. The front associated with the gulf low will push into
the eastern gulf by Sunday afternoon and early evening producing
Storm force winds. As the frontal boundary crosses over the
panhandle strong wind gusts upwards of 50 mph will develop with
max gales over the inner channels. Secondary wrap will cross over
the southeast coastal waters this evening with storm force winds,
then push over the southern panhandle producing more storm force
winds over the southern inner channels. With 925 mb winds upwards
of 60 to 70 kt from secondary wrap have issued a High Wind
Warning for AKZ27 and 28 Sunday evening into Monday morning.
Localized gusts of 60 to 65 mph expected.

Rain showers this morning will begin to taper off just in time
for steady rain to develop in the afternoon and last into the
night. More heavy rain is expected due to long fetch of moisture
along the front. Temperatures, already in the upper 30s to low
40s will remain fairy steady through the day and only show a
slight decrease overnight. The exceptions will be along the
Klondike highway where a Winter Storm Warming is in effect tonight
and lasting into Tuesday. Stronger winds will produce blowing snow
in addition to the heavy snow accumulation. Hyder still have some
cold air in place for a mix of snow this morning but as the front
moves in should have an overall warming trend for all rain today
and this evening.

Models were in fair agreement with overall synoptic pattern. As there
were some timing issues with the 925 mb winds decided to keep
with NAM due to initialization. Locations over the Central and
Coastal panhandle gusts were getting close to 60 mph, but as main
energy is just to the south held off on extending the High Wind
Warning. Forecast confidence is average.

.LONG TERM...High winds for the southern panhandle will end early
in the extended range forecast period on Monday morning. That
afternoon, high winds for Skagway are looking likely. High wind
watch was continued vice issuing a warning, as this is still more
than 24 hours away. As with the wind, precipitation that arrives
in force during the short term forecast period will remain into
the extended range forecast. The difference is that the
precipitation, heavy at times, will last longer than the wind
will. Low to mid level temps associated with this front looking
too warm for snow, so precipitation will begin as rain for just
about everywhere except the highways, Haines, and Skagway. Yakutat
may possibly see some snow too on Monday. Post frontal cold air
advection beginning Monday evening will increase the probability
of snow, but another warm air push from the south on Tuesday should
result in the snow level rising again. Temperatures for the second
half of the week are looking cooler with a more zonal pattern in
the upper levels and snow looks more likely, although current
forecast grids depicting only likely pops due to this being fairly
far out in the future. Still, the pattern will remain active
through the end of long range forecast, so look for these pop
values to increase in subsequent forecast issuances.

Updated Tuesday and Tuesday night pressure and wind using ECMWF.
PoP Monday morning through Tuesday night from a blend of the
Canadian NH and SREF with QPF from the Canadian. No change to
temperatures tonight. Snow levels Monday through Tuesday night
from GFS but adjusted using the forecast 40F and 32F isotherms.
Overall forecast confidence limited to average.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Strong Wind from 3 PM AKST this afternoon through this evening
     for AKZ022-026.
     High Wind Warning from 9 PM this evening to noon AKST Monday for
     AKZ027.
     Strong Wind this evening for AKZ021-024.
     Strong Wind from 3 PM AKST this afternoon through late tonight
     for AKZ023-025.
     High Wind Warning from 9 PM this evening to 9 AM AKST Monday for
     AKZ028.
     Strong Wind late tonight for AKZ019.
     Winter Storm Warning from 6 PM this evening to 6 AM AKST Tuesday
     for AKZ018.
     High Wind Watch from Monday morning through Monday evening for
     AKZ018.
     Strong Wind this evening for AKZ017.
MARINE...Storm Warning for PKZ036-041>043-051-052.
     Gale Warning for PKZ011-021-022-031>035-053.
     Small Craft Advisory for PKZ012-013.
&&

PRB/Fritsch

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