Wind Chill Advisory 7, NWS Anchorage, AK

051 
WWAK41 PAFC 200052
WSWAER

URGENT - WINTER WEATHER MESSAGE
National Weather Service Anchorage AK
352 PM AKST Sun Jan 19 2020

AKZ131-200200-
/O.EXP.PAFC.WC.Y.0007.000000T0000Z-200120T0100Z/
Northeast Prince William Sound-
Including the cities of Valdez and Thompson Pass
352 PM AKST Sun Jan 19 2020

...WIND CHILL ADVISORY WILL EXPIRE AT 4 PM AKST THIS AFTERNOON...

The temperature through Thompson Pass will begin to rise this 
evening as winds slowly diminish.

$$

http://www.weather.gov/afc

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
322 AM AKST Sun Jan 19 2020

.ANALYSIS AND UPPER LEVELS...

A broad upper level low centered over western Russia is
dominating the weather pattern across much of Alaska. Scattered
rain/snow showers are continuing across the Bering/Aleutians this
morning under a weak front. Snow is also presently occurring
downstream of the trough axis associated with the aforementioned
upper low, with a few inches of accumulation possible in the
Bristol Bay region. The upper level pressure gradient over
mainland Alaska has significantly decreased over the last few
days. As such, outflow gap winds will continue to diminish.
Precipitation on the north side of a Gulf low will gradually move
into Prince William Sound through this morning.

&&

.MODEL DISCUSSION...

As discussed yesterday, model disagreement still exists with
regards to the low approaching the western Kenai Peninsula. The
GFS is the most notably farther south and slowest of any of the
main synoptic models, though cannot be completely discounted. As
this is applicable to today's time frame, high-res models can also be
examined. These indicate the low moving onshore near Seward Monday
morning as does the RGEM, NAM and European models, making this the
preferred solution as this time. If this track comes to fruition,
accumulating snow would be likely for the Cook Inlet region
Monday into early Tuesday.

&&

.AVIATION...

PANC...VFR conditions and light winds will persist.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...

A surface low over the northwest Gulf will move north today to
just south of Prince William Sound by evening. The associated
front will move from east to west, bringing increasing winds
across the northern Gulf where it will then slowly move east and
weaken. Precipitation will also spread westward today, with snow
reaching the eastern Kenai Peninsula this afternoon. Snow could be
heavy at times on the eastern Kenai through Monday morning with
10 to 20 inches of snow possible, with the highest amounts north
of Moose Pass. For areas around Cook Inlet, there will be chances
of snow through Monday as most of the moisture stays near the
coast. Monday night looks like the best chance of snowfall inland
as an upper level trough begins to push toward the area from the
southwest. The airmass associated with this system is
considerably warmer than what has been sitting over the area for
the last few days, with temperatures expected to be in the 20s
over Anchorage on Monday. There is the potential for rain mixing
in with snow along the Gulf Coast, mainly near Cordova.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...

A weak band of snow showers situated west of King Salmon will
continue to bring show showers for areas from Dillingham to Pilot
Point. This band will shift slightly westward as it weakens
through the afternoon, bringing a chance of snow showers for Port
Heiden. Snow showers will taper off into the evening, leaving most
of Southwest Alaska under cold and dry conditions through Monday.
The next chance of snow will move in on Monday afternoon as
another band of snow showers, associated with an upper level
disturbance, tries to set up along the Southwest coast. However,
there is still some uncertainty in where it will set up, but
inland locations should remain dry through Tuesday.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...

Snow showers will persist across much of the Bering as a front
over the central Bering and Aleutians weakens through this
evening. The main feature driving the weather is a low over the
northern Bering, which models have come in to better agreement for
today. As this feature diminishes by Monday morning, a second low
will likely develop through Monday afternoon over the northern
Bering. There is still some uncertainty in timing and placement of
this second low, but it should remain north of the Pribilofs
through Tuesday. Expect snow showers and colder temperatures to
move in over the next few days across the Bering and Aleutians.

&&

.MARINE (Days 3 through 5...Tue through Thu)...

The primary areas of concern areas during this time period will
be along the Aleutian Chain. One system will just track along the
south side of the Chain Tuesday into Wednesday. This could bring
easterly winds as high as high end gale force, but for now it
looks like the strongest winds will stay south of the marine
zones. The next system will push towards the Western Aleutians
(Zones 177-178) late Wed into Thu. This system looks to bring a
healthy swath of gale force winds from the Central to the Western
ALeutians.

&&

.LONG TERM FORECAST (Days 3 through 7: Tuesday through Saturday)...

On Tuesday, zonal flow is expected to exist in the Bering Sea and
a diffuse pattern (not much going on) will exist in Southcentral
AK. This will change Wednesday as long range guidance continues to
show an upper level blocking ridge building from the north
Pacific across the AKPEN and into the Bering Sea. An anchoring
high will be present by Friday, securing the position of this
ridge for the remainder of next week.

This means high pressure for the Bering Sea and cold air over
mainland AK. It is possible for deep cold to return to the Copper
River Basin late next week with this pattern. Offshore gusty winds
will be possible in southwest AK and the western Gulf. Low
pressure will be present somewhere in the Gulf of Alaska, but this
is one feature guidance is having trouble with. We know a trough
will dig south through eastern Alaska into a low in the gulf.
However, there is disagreement where this will set up. For now it
looks like the eastern Gulf will be impacted by any low pressure
setup, but confidence is low with this aspect of the forecast.
This pattern shift is something we will be paying close attention
to, so expect modifications with the forecast in coming days.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Wind Chill Advisory: 131.
MARINE...Gale Warning: 119 120 127.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...AP
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...AH
MARINE/LONG TERM...BB

SPECIAL WEATHER STATEMENT
National Weather Service ANCHORAGE AK
830 AM AKST Sun Jan 19 2020

AKZ181-200115-
Alaska Peninsula-
Including the cities of Cold Bay and Sand Point
830 AM AKST Sun Jan 19 2020

...Possible ashfall from Shishaldin Volcano...

Ash has been detected by satellite imagery during the ongoing
eruption of Shishaldin volcano. Easterly wind flow aloft has
brought the plume eastward toward Cold Bay. Trace accumulation of
ash is possible for the next several hours as the plume remains
on an easterly trajectory. Winds aloft turn out of the northwest
this afternoon which should take the plume southward over marine
area.