Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 01/16/20

Southeast Alaska Forecast Discussion

National Weather Service Juneau AK

 246 PM AKST Wed Jan 15 2020

.SHORT TERM...While the cold continues across Southeast Alaska
today, actual temperatures have warmed slightly across many parts
of the area, mainly due to greater mixing of the lower boundary
layer. Estimated from MDCRS soundings, some parts of the region
had a very low inversion of 300 feet, which mixed out around
midday leading to some sharper temperature rises. However, with
wind comes wind chills; thus it was still unpleasant for many
Southeast Alaskans to be outdoors for long. The wind chill warning
for White Pass still runs into tomorrow morning. If one calls 50
below wind chill a break, anyone venturing outside on the high
point of the Klondike Highway today experienced one. Despite the
respite, we leave the warning in place as we expect both winds to
rise and temperatures to fall overnight. In fact, the warning may
need to be extended into early afternoon Thursday, but we will
take a second look Thursday morning before being absolutely
certain.

Gusty high winds in Juneau continue as weak cold air advection
from Canada continues through our mountain passes. Cross barrier
flow, while not extraordinary as estimated by the models should
strengthen tonight. All high res models are supporting a sharp
rise in wind gusts late tonight into Thursday morning. Therefore,
the gusts to 85 mph for Downtown Juneau and Douglas still seem
reasonable. In fact, as the gradient responds to a low pressing up
the BC Coast from the south, we should see the tightening gradient
even further. Now heading into the weekend, a new front looks to
form out in the North Pacific. We have gale force easterlies
building over the gulf. This should support another period of
potentially high winds for Downtown Juneau late Friday into at
least Saturday night. To prepare for this, we have dried out
conditions by reducing pop markedly for the northern Panhandle
during this time, in line with temperatures still well below
normal. But we have also begun warming temperatures a bit earlier
on Sunday as we allow the precipitation bands to climb north.
Thus, late Saturday night into Sunday, we are looking for possibly
significant snow potential for the southern Panhandle but much
lighter snow for the north.

Lastly, we did nudge upward temperatures for the next 30 hours over
the Inner Channels using the HRRR which seems to be performing
far better than the NBM`s disappointing cold bias. We still left
the heavy freezing spray for Sumner Strait late tonight into
tomorrow morning, as Stikine River outflow may be pretty
impressive overnight, and temperatures in Wrangell are indeed
quite cold in the middle teens.

.LONG TERM...Change is still in the works for the next week as
the cold dry weather starts gives in to warming temperatures and
rain creeping into the forecast, perhaps even for some locations
in the northern Panhandle. Forecast confidence past the weekend
is still suffering from what the upstream upper level features
will do, but the overall message is a gradual warm up with
southerly onshore flow. Forecast confidence is moderate favoring
the WPC and NBM for updates.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...High Wind Warning until 9 PM AKST Thursday for AKZ025.
     Strong Wind from late tonight through Thursday morning for
     AKZ022.
     Strong Wind through Thursday morning for AKZ021.
     Strong Wind through Thursday afternoon for AKZ019.
     Wind Chill Advisory from 9 PM this evening to noon AKST Thursday
     for AKZ019.
     Wind Chill Warning until 10 AM AKST Thursday for AKZ018.
     Strong Wind through late tonight for AKZ018.
MARINE...Heavy Freezing Spray Warning for PKZ011-031.
     Heavy Freezing Spray Warning for PKZ011.
     Heavy Freezing Spray Warning for PKZ011.
     Heavy Freezing Spray Warning for PKZ011.
     Heavy Freezing Spray Warning for PKZ013.
     Heavy Freezing Spray Warning for PKZ031.
     Heavy Freezing Spray Warning for PKZ012.
     Heavy Freezing Spray Warning for PKZ035.
     Storm Warning for PKZ012.
     Gale Warning for PKZ013-021-022-031-043-051.
     Small Craft Advisory for PKZ011-032>036-041-042-052-053.

&&

$$

JWA/EAL

Visit us at http://www.weather.gov/Juneau