Wind Chill Advisory 2, NWS Anchorage, AK

153 
WWAK41 PAFC 100054
WSWAER

URGENT - WINTER WEATHER MESSAGE
National Weather Service Anchorage AK
354 PM AKST Wed Jan 9 2019

AKZ131-101430-
/O.CON.PAFC.WC.Y.0002.000000T0000Z-190110T2100Z/
Northeast Prince William Sound-
Including the cities of Valdez and Thompson Pass
354 PM AKST Wed Jan 9 2019

...WIND CHILL ADVISORY REMAINS IN EFFECT UNTIL NOON AKST THURSDAY
THROUGH THOMPSON PASS...

* WHAT...Very cold wind chills expected. Expect wind chills from 
  35 below zero to 45 below zero.

* WHERE...Through Thompson Pass.

* WHEN...Until noon AKST Thursday.

* ADDITIONAL DETAILS...The dangerously cold wind chills could 
  cause frostbite on exposed skin in as little as 10 minutes.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Wind Chill Advisory means that cold air and the wind will
combine to create low wind chills. Frostbite and hypothermia can
occur if precautions are not taken. Make sure you wear a hat and
gloves.

&&

$$

http://www.weather.gov/afc

097 
WWAK41 PAFC 101307
WSWAER

URGENT - WINTER WEATHER MESSAGE
National Weather Service Anchorage AK
407 AM AKST Thu Jan 10 2019

AKZ131-110100-
/O.EXT.PAFC.WC.Y.0002.000000T0000Z-190111T0100Z/
Northeast Prince William Sound-
Including the cities of Valdez and Thompson Pass
407 AM AKST Thu Jan 10 2019

...WIND CHILL ADVISORY NOW IN EFFECT UNTIL 4 PM AKST THIS
AFTERNOON THROUGH THOMPSON PASS...

* WHAT...Very cold wind chills expected. Expect wind chills from 
  35 below zero to 45 below zero.

* WHERE...Through Thompson Pass.

* WHEN...Until 4 PM AKST this afternoon.

* ADDITIONAL DETAILS...The dangerously cold wind chills could 
  cause frostbite on exposed skin in as little as 10 minutes.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Wind Chill Advisory means that cold air and the wind will
combine to create low wind chills. Frostbite and hypothermia can
occur if precautions are not taken. Make sure you wear a hat and
gloves.

&&

$$

http://www.weather.gov/afc

193 
WWAK41 PAFC 110102
WSWAER

URGENT - WINTER WEATHER MESSAGE
National Weather Service Anchorage AK
402 PM AKST Thu Jan 10 2019

AKZ131-110215-
/O.EXP.PAFC.WC.Y.0002.000000T0000Z-190111T0100Z/
Northeast Prince William Sound-
Including the cities of Valdez and Thompson Pass
402 PM AKST Thu Jan 10 2019

...WIND CHILL ADVISORY HAS EXPIRED THROUGH THOMPSON PASS...

$$

http://www.weather.gov/afc

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
500 AM AKST Wed Jan 9 2019

.ANALYSIS AND UPPER LEVELS...
The upper level pattern is undergoing a transition with a low
pressure across the northern coast pushing a strong short wave
across the Kuskokwim Delta early this morning. The stacked low
south of the Alaska Peninsula remains stationary with its front
initiating a few rain and snow showers across the Alaska Peninsula
and Kodiak Island. Another front, extending from a Kamchatka low,
is weakening, with scattered snow showers developing along the
diminishing boundary across the central Aleutians and Bering.
Otherwise, Southcentral is seeing another morning with calm and
quiet conditions.

&&

.MODEL DISCUSSION...
Models continue to be in consensus with the near term forecast.
Only minor changes were needed for the morning package as agreement
with the next big storm system remains consistent on the tracking
and intensity as it moves over the western Aleutians to the Bering
by Thursday morning.

&&

.AVIATION...

PANC...VFR conditions are expected through late Thursday morning
with light northerly winds as the ridge across the interior
remains dominant. &&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2: Today
through Thursday night)...

A trough moves across the Cook Inlet to MAT-SU corridor late this
afternoon and evening. It should bring increased chances of light
snow with a emphasis on upslope areas of the Talkeetna Mountains.
Should see some clearing as the trough moves east tonight and
weakens. Cold air then spreads in across Southcentral in the wake
of the trough bringing a return to fairly chilly conditions
Thursday and Thursday night. Many inland areas should drop well
below zero Thursday night into Friday morning with the coldest
spots over the Copper River Basin and Susitna Valley.

Outflow winds will likely ramp up today across the North Gulf
Coast, eastern/southern Kenai Peninsula and continue through
Thursday before weakening Thursday night. Cold advection and
phasing up upper flow and passage of upper wave will give rise to
westerly gales across the Barren Island marine zone tonight.
Additionally heavy freezing spray will develop from near Kamishak
Bay to the Barren Islands.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3/Wednesday
through Friday)...
Cold air is on its way into southwest Alaska. The front currently
pushing through the area is dropping snow as expected around
Dillingham and inland areas north and east. Still expecting a few
inches out of this system when all is said and done. Highest
totals will be in unpopulated areas with no real way to know how
much has fallen, so did not issue any hazards with this storm.

After the storm exits this morning (satellite shows it moving
north and east) the shift to colder weather will begin. Some low
level stratus, also clearly depicted on satellite, will hold
temperatures on the warm side for today. However, the cold air
push coming from the arctic by way of Interior AK will not be held
off for long. Expect temperatures to plummet tonight (20 to 30
below) for interior areas of southwest Alaska and remain cold for
the rest of the week. Minimum temperatures tomorrow night will be
30 to 40 below. Close to the coast in the Y-K Delta, winds may be
strong enough to induce some wind chills below -40F, so we are
looking into a wind chill advisory for this area. Stay tuned as we
dial in that forecast.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 3/Wednesday
through Friday)...
A weak front sits over the central Bering, largely stationary but
drifting ever so slightly. It sits just west of the Pribilofs,
attached to its parent low over Kamchatka and sandwiched between
cold air on its backside and another low pressure system to its
east. This weak front is all that the Bering has going for the
moment, so weather will generally be quiet today. This will all
change tomorrow into tomorrow night, when the forecasted powerful
low pulls north from the Pacific and begins to send weather across
the western and central Aleutians. It is still expected to reach
peak strength before reaching our forecast area, so it will be on
the decline when it gets here. However, being it such a powerful
system, even though it will not be at its strongest there will
still be a large swath of storm force winds that crosses the
Aleutians and moves into the Central Bering tomorrow night. The
storm will then retrograde west on Friday, taking winds with it.

&&

.MARINE (Days 3 through 5)...

Beginning Friday, there is high confidence that a weakening but
still strong North Pacific low will be centered just south of the
Rat Islands of the Aleutians. A wide swath of easterly gale force
winds will cover most of the Western Bering with an area of storm
force winds expected to be impacting the western third of zone
413 and the southern half of zone 411. The low is expected to move
to the west then slowly push southwest of Shemya Friday night.
This will bring storm force winds south across the western half of
zone 178, including Shemya and Attu Island Friday evening through
Saturday morning. As the low continues to push further west,
another, albeit weaker, low is expected to move north across the
central Aleutians. There is still a fair amount of uncertainty
with this system, thus lower confidence, but there is overall
agreement that northeasterly gale force winds will continue across
a good portion of the western Bering Sea, with the potential for
areas of southerly gales to develop east of the Pribilofs by
Saturday night. Additionally, with the next system pushing north,
this should keep cold arctic air, and thus heavy freezing spray
potential, confined to the Northern Bering Seas, mostly over zone
185 over the weekend.

Over the Gulf of Alaska, conditions are expected to remain rather
tranquil before a front sweeps north across the area on Sunday.
Right now, winds are expected to remain predominately below gale
force, though there is still a fair amount of uncertainty
regarding the timing and track of this system.

&&

.LONG TERM FORECAST (Days 4 through 7)...

The long term forecast begins Saturday with a big pattern change
in store for the southern mainland and Bering Sea. Brutally cold
arctic air under an upper level 'Polar Vortex' low will be
retreating north as the low is shoved north into the Arctic Sea by
a building inverted upper level ridge from the south. At the same
time, an upper level low will begin to build back in over the
Bering while a long wave ridge will build further east over the US
west coast. This will set the stage for deep southerly flow to
push north into the southern mainland by Sunday, bringing warm air
and plenty of moisture with it. Models depict multiple surface
features rotating around the base of the upper low into mainland
Alaska, though details surrounding these features are still murky
due to model inconsistencies. The first feature that both the EC
and GFS models are keying in on is a surface low (GFS) or short
wave trough (EC) moving north from the North Pacific and across
the AKPEN and southwest mainland around Sunday night. The track
with this system is vital to knowing the specific impacts. For
example, the GFS solution brings the low a bit further east over
the AKPEN, which is historically conducive for bringing a Chinook
wind into the Anchorage area. Meanwhile, the EC solution would
likely keep winds out of Anchorage and temperatures a bit cooler.

Regardless, there is high confidence that the pattern change will
bring much warmer and wetter weather to the region through at
least the middle of next week.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...HEAVY FREEZING SPRAY 121 127 130 139 160 180 185.
         Storms 177 178.
         Gales 127 130 173 174 175 176.
. FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...ALH
AVIATION...KH
SOUTHCENTRAL ALASKA...BC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...BJB
MARINE/LONG TERM...KVP