Gale Warning 44, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
242 PM AKST Fri Feb 1 2019

.SHORT TERM.../Through Sunday night/ Strong high pressure in the
southern Yukon continues to drive strong outflow and cold
temperatures across the panhandle through the weekend. Winds have
been rather high in many outflow areas today. Notable
observations have included 45 to 50 kt with gusts to hurricane
force in Lynn Canal, gusts to 55 kt out of Taku Inlet, and 50 kt
winds out of Cross Sound. Temperatures have also been rather cold.
Lowest temperatures are along the klondike highway where below
zero readings are being observed and below freezing temps have
reached as far south as Hydaburg and Annette.

For the short range, the outflow will continue through Sun but
will be gradually diminishing in intensity through the period. The
reason is two fold. first the low to the SE of the panhandle will
weaken and push off to the east through Sat which will weaken the
pressure gradient along the coast mountains. Second is the high
in the Yukon will be starting a SE drift into northern British
Columbia. North/south channels will gradually become less
favorable for winds as it does so, while east/west channels will
see an uptick in winds into Sat. Winds will continue to diminish
into Sun as the cold high gets pushed off to the east. Most areas
should be below small craft criteria by Sun afternoon (except Lynn
Canal).

Meanwhile, temperatures are expected to be at their coldest Sat
morning into Sun morning with wide spread lows in the single
digits and teens with highs on Sat struggling to get out of the
teens. Gradual warming trend into Sun as outflow diminishes.

Model agreement is still rather good so minimal changes needed at
this point. Used mainly Nam and Gfs for guidance.

.LONG TERM.../Sunday thru Friday issued 10 PM Thursday/
Models are notorious for moving upper ridges too rapidly
eastward. Each successive run when you have a high amplitude ridge
over the central Gulf will delay changes to the flow a little
slower. So it was with this pattern which gives our area strong
northerly flow aloft starting Sun morning. The first indications
of an upper disturbance moving through this ridge is on early Mon
morning, but the speed and depth of the shortwave is
different on the 01/00Z operational model runs at 84 hours
projection. Those early differences can rattle one's confidence.

There was enough agreement to warrant slowing down precipitation
making it to Yakutat, so lowered the probability there, keeping
the rest of the Panhandle dry until late Mon afternoon. There's
pretty good agreement that the upper ridge will rebuild to our
West after this disturbance passes but all guidance insisted there
is at least a chance of snow on Tue and beyond. After that, just
hit the area with a broad brush chance of snow north, and chance
of rain and snow south.

Wind and the position of any arctic front was also uncertain when
the models aloft indicate that much uncertainty. From Mon onward
there was not indication of the strong winds that we are having
through Sun, especially in the northern realms. So, overall
confidence in these forecasts is low from Mon and beyond, and it
is hoped that later model runs will ramp up certainty on the
position of the upper ridge and any shortwaves that try to beat
through it.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Strong Wind through late tonight for AKZ026.
     High Wind Warning until 9 PM AKST Saturday for AKZ025.
     Strong Wind until 6 PM AKST this evening for AKZ021.
     Strong Wind through Saturday afternoon for AKZ018-019.
     Wind Chill Advisory until 9 AM AKST Sunday for AKZ018.
MARINE...Heavy Freezing Spray Warning for PKZ012-013-031.
     Heavy Freezing Spray Warning for PKZ032.
     Hurricane Force Wind Warning for PKZ013.
     Storm Warning for PKZ012-022.
     Gale Warning for PKZ021-031>035-043-051.
     Small Craft Advisory for PKZ011-036-041-042-052-053.

&&

EAL/JCC

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