Blizzard and Heavy Snow in Alaska, January 25 to 26, 2020

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
618 AM AKST Sat Jan 25 2020

.SHORT TERM...Satellite imagery this morning showing remnants of
weakening front associated with a low in the North Central Gulf
tracking over the central and north east AK Panhandle. Snow/snow
showers for these northern areas have been diminishing this
morning with only a few inches of additional snow expected. Over
the North Pacific satellite shows the next low tracking northward
into the Se Gulf. Precipitation in the form of rain already
falling over the southern areas from the advancing front. Issue
for the short term is the track/strength of this low and how the
front will be resolved and triple point low development along the
front for Sunday. For now, and this is with fair amount of model
differences, thinking is the low will track northward along the
panhandle coast through Saturday and Saturday night with first
front spreading precip northward. The low will move into the NE
gulf early Sunday with the triple point low forming in the SE
Gulf which will then move over the central panhandle.

Nuts and bolts of the weather: snow showers diminish over the
norther areas Saturday while rain develops over the southern
panhandle. Central panhandle will have snow develop Saturday
afternoon and evening, but as temperatures start to warm will have
a change to rain or a rain/snow mix. Far northern panhandle will
have snow start this evening and expect to remain snow until late
Sunday evening. Winter Weather Advisories have been issued for
the Juneau and Yakutat area Saturday night with accumulations in
the 3 to 5 inch range. Warmer air moving up and rising snow levels
should transition snow to more rain and thus limit Sunday snow
accumulations. Winter Storm Warnings were issued for Haines and
Skagway from Saturday evening through Sunday evening, especially
the highways, due to the multiple fronts. Storm total snow
accumulations of 10 to 22 inches, highest along the Klondike
highway. While good confidence in the precipitation timing here
is were the uncertainty lays: timing of Central Panhandle warm up
which could limit snow totals with either lower snow ratio, and
QPF amounts for the central and northern locations. NAM especially
had less cohesive frontal structure and much lower QPF for Haines
and a faster warm up for Juneau area. GFS put out 6 hour QPF
amounts will over half an inch at times for the same period as the
lower NAM values. With regards to the strength of the low, main
impact was marine winds increase to gale force earlier on
Saturday and strong winds along the southern panhandle and coastal
areas. As the lows/fronts develop hopefully there will be
increased confidence in timing of these features.

.LONG TERM.../Monday through Saturday/As of 10 PM Friday/We begin
the period Monday with ongoing precipitation occurring region wide
associated with a wave spinning around low pressure in the Gulf.
Temperatures though will be in the middle of an upward trend
though to start this period with consistent southerly flow into
the panhandle. Multiple locations are likely to top out in the 40s
several times next week. This will result in p-type issues
throughout the week with many in the central to norther panhandle
likely to see at the least snow mixing in with rain. Areas to the
south most likely stay warm enough that any precip will be rain.
However, areas furthest north such as Haines, Skagway and Yakutat
will see the best chances at significant snowfall as nighttime
temps will still be cold enough to support snow rather than rain.
Thus our Monday storm also begins a period where multiple
disturbances will continue to impact the region over the long term
as the pattern remains very progressive and continued southerly
flow will provide enough moisture that no prolonged breaks in
precipitation can be easily anticipated.

Model agreement on exact timing and impacts of these various
disturbances this far out remains pretty poor, but enough
agreement does exist that the conditions around Tuesday night into
Wednesday will be the wettest and probably also the windiest. WPC
guidance insists that this low will be very tightly wound and
storm force winds may be possible particularly in the open Gulf,
but also strong winds making their way into the inner channels.
Have opted not to bite off on this whole heartedly in the current
forecast, but did raise winds in the open water notably to make
note that we will be looking at future guidance to determine just
how impactful this storm will be. Models are also showing another
storm late week, but the discrepancies between solutions at this
point are far too great to make any real determination of much or
how little this one will do.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Strong Wind from noon AKST today through this evening for AKZ027.
     Winter Weather Advisory from 6 PM this evening to 5 AM AKST
     Sunday for AKZ025.
     Strong Wind from this evening through late tonight for AKZ022-
     023.
     Strong Wind from 9 AM this morning to 3 PM AKST this afternoon
     for AKZ028.
     Winter Storm Warning from 6 PM this evening to 9 PM AKST Sunday
     for AKZ018-019.
     Winter Weather Advisory from 9 PM this evening to 9 AM AKST
     Sunday for AKZ017.
MARINE...Gale Warning for PKZ036-041>043-051-052.
     Small Craft Advisory for PKZ021-022-031>035-053.

&&

PRB/JDR

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