Blizzard Warning 1, NWS Anchorage, AK

548 
WWAK42 PAFC 131301
WSWALU

URGENT - WINTER WEATHER MESSAGE
National Weather Service Anchorage AK
401 AM AKST Sun Jan 13 2019

AKZ195-140100-
/O.CAN.PAFC.BZ.W.0001.000000T0000Z-190113T2100Z/
/O.EXB.PAFC.WW.Y.0004.190113T1301Z-190114T0100Z/
Pribilof Islands-
Including the city of Saint Paul
401 AM AKST Sun Jan 13 2019

...WINTER WEATHER ADVISORY IN EFFECT UNTIL 4 PM AKST THIS
AFTERNOON...
...BLIZZARD WARNING IS CANCELLED...

* WHAT...Snow and blowing snow reducing visibilities to one half
  mile at times expected. Gusty northeast winds between 25 to 40
  mph. Additional snow accumulations of 1 to 3 inches are 
  expected.

* WHERE...Pribilof Islands.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Weather Advisory for snow and blowing snow means periods
of snow and blowing snow will cause primarily travel
difficulties. 

&&

$$

AKZ155-140100-
/O.EXT.PAFC.WW.Y.0004.190113T1500Z-190114T0100Z/
Kuskokwim Delta-
Including the cities of Bethel, Hooper Bay, and Nunivak Island
401 AM AKST Sun Jan 13 2019

...WINTER WEATHER ADVISORY NOW IN EFFECT UNTIL 4 PM AKST THIS
AFTERNOON WEST OF BETHEL...

* WHAT...Snow and blowing snow reducing visibilities to one half
  mile at times expected. Gusty northeast winds between 25 to 40
  mph. Total snow accumulations of up to 2 inches are expected.

* WHERE...Kuskokwim Delta west of Bethel.

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

* ADDITIONAL DETAILS...Areas of poor visibility are likely. Winds
  gusting as high as 35 mph will cause areas of blowing and 
  drifting snow. The cold wind chills as low as 25 below zero 
  could cause frostbite on exposed skin in as little as 30 
  minutes.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Weather Advisory for snow and blowing snow means periods
of snow and blowing snow will cause primarily travel
difficulties. Expect snow covered roads and limited visibilities,
and use caution while driving.

&&

$$

http://www.weather.gov/afc

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
504 AM AKST Sat Jan 12 2019

.ANALYSIS AND UPPER LEVELS...
The synoptic pattern is being kicked into motion by an upper level
subtropical jet which is amplifying across the North Pacific. This
jet is kicking a closed low just south of the Alaska Peninsula
toward the Bering. Another sprawling low, with a closed center
south of the Rat Islands, is on a track toward the Central
Aleutians. The upper low that dominated the central interior on
Friday, is now flattening out as the the jet drives the next low
toward the Alaska Peninsula. At the surface, the pattern persists
from yesterday with the coldest temperatures across the mainland
and the gustiest conditions noted across the Bering.

&&

.MODEL DISCUSSION...
Models are in good agreement on the overall synoptic change;
however, there is still uncertainty on how fast the pattern will
warm across the southern mainland. There are also minor
differences in the track and timing of the subsequent fronts
associated with the next developing system expected to move across
the North Pacific to the southern Bering on Sunday. Adjustments
on the morning package were made using the influences from the NAM
across Southcentral and the Gulf, with GFS mainly used across the
Southwest and Bering.

&&

.AVIATION...
PANC...Brief IFR conditions were included for early this morning
in a tempo group as low stratus is trapped under a temperature
inversion. Otherwise, kept a scattered low deck through the
afternoon as there is high uncertainty in the timing of the lower
ceilings. Weak isentropic lift is expected to initiate a few
flurries with light northerly expected to persist through late Sunday
morning.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3:
Today through Sunday Night)...

A pattern change toward warmer, wetter, and locally windy
conditions is on track for this weekend. The first in a series of
fronts heads north today bringing rain to Kodiak Island this
morning and spreading snow or a mix of rain and snow to the Gulf
Coasts and Kenai Peninsula through tonight. Cold air damming west
of the Chugach will mitigate downslope drying typical with SE cross-
barrier flow and allow some light snow to work west of the
Chugach. Downslope will become more of a factor on Sunday as warm
advection in advance of the next front heading north erodes the
cold dome. So expect the brunt of frontal precipitation to hold
mainly along the coast Sunday with minimal amounts inland.
Temperatures will continue to warm through the weekend with
coastal areas rising to well above freezing and many inland areas
of Sunday climbing into the upper teens to lower 30s, coolest in
the Copper River Basin.

Gap winds will increases today across Turnagain Arm/Portage Valley
today. This combined with falling snow will produce locally low
conditions in blowing snow from Portage Valley to Turnagain Pass
tonight into Sunday morning. Snow should transition toward a mix
in these locals on Sunday and end the blowing snow threat. Gales
to localized storm force winds can be expected over the Gulf
Marine areas, mainly western Gulf, through Sunday.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3...Sat
through Mon)...

A closed low south of the Eastern Aleutians, moving north, will
spread increasing chances for snow across Southwest tonight.
However, with strong northeast offshore winds, this will generally
keep precipitation on the lighter side since this low does not
have much of a moisture surge with it. Some coastal blowing snow
is possible along the Kuskokwim Delta. Otherwise, for today, the
main story will remain bitterly cold temps with the wind chill
advisory continuing into the midday.

A warm front will move into Southwest Saturday night into Sunday,
bringing a much more impressive surge of moisture. The warm air
will quickly penetrate Bristol Bay and warm that area up, but
favorable northeast winds 20-30 MPH will continue across the
Kusko Delta. With a burst of 2-3" of snow and strong offshore
winds, expect significant areas of blowing snow possibly reducing
visibilities to a half mile or less during the morning and early
afternoon Sunday before the front moves north and the southerly
winds kick in. A blowing snow advisory may be needed, but held off
for now to get a better handle on timing.

The strong southerly flow continues through Monday, but
precipitation will be more hit or miss behind the dryslot of the
strong warm front.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3...Sat
through Mon)...

A vertically stacked low south of the Western Aleutians continues
to push its frontal boundary across the Chain as it progresses
northeastward towards the Pribilof Islands for Sunday morning.
This low remains storm force based on latest ASCAT imagery and
observations at Shemya. As it moves over the central Aleutians on
Sunday, the low center that has been dominating the pattern
merges with a deeper low center that spins up further east from
the first low. Northeasterly, gale force winds will spread across
most of the Bering and Pribilofs through Sunday morning, until
this system changes positions and starts to bring a southerly flow
by Sunday evening.

One area of concern is would be the frontal system Saturday
through Sunday morning for the Pribilof Islands, which could see
reduced visibilities and blowing snow for a brief period before
the southerly winds kick in. By Monday morning, winds should calm
down a bit for the Aleutians and Pribilofs, with some gales
remaining in the north central Bering, which will diminish to
small crafts throughout the day.

&&

.MARINE (Days 3 through 5)...

Beginning the marine extended period forecast on Monday, a ~965 mb
low will be slowly moving north over the central Aleutians and
into the Bering, centered near the Pribilofs by Tuesday. The
Bering will be under broad cyclonic flow during this time with
areas of gale force winds expected on the periphery of the low, to
the east and west of the Pribilofs. Winds will diminish through
the day as the low weakens and slowly moves north, with mostly
just small crafts expected by Tuesday afternoon. Wave heights will
also be subsiding through Wednesday, decreasing from near 20 ft
west of the Pribilofs on Monday to only 10-15 ft by Wednesday.

The Gulf of Alaska will see a more active pattern as a series of
storm systems move through, kicking up winds and wave heights
through the first part of the week. Right now, it looks like winds
should remain predominately below gale force, though areas east
and north of Kodiak Island and though the Barren Islands will
likely see periods of gales Monday night into Tuesday morning.
Another system is expected to push through the northern Gulf
Tuesday into Wednesday, but there is still a fair amount of
uncertainty regarding the strength and timing this far out.

&&

.LONG TERM FORECAST (Days 3 through 7)...

Beginning Monday, the southern mainland will be under broad
southerly flow as the area will be caught in between an upper
level low over the Bering and an upper ridge axis over the Pacific
west coast. Warm and moist air will be pumped north into the Gulf
Coast, with a barrage of fronts and lows streaming into the area.
Models still show a chaotic mess in terms of specific features,
with timing and placement differences, but overall it appears the
windward (east) side of the AKPEN, Kodiak, and the Kenai
Peninsula will get the brunt of the action with typical leeward
locations expected to remain mostly dry due to downsloping. These
systems don't look to be as strong the ones that moved through
the area over the New Years holiday due to weaker upper level jet
support. Temperatures are expected to remain well above average
through the middle part of the week. For snow lovers, snow levels
look to rise above sea level in the mountains, meaning rain may
fall at the lower elevations along the coastal mountains from the
Kenai Peninsula to the Chugach along the Gulf Coast.

By the end of the week, models begin hinting at another pattern
change with the upper low over the Bering retreating north
allowing ridging to potentially build back in over the southern
mainland, allowing for a drying/cooling trend over the area.
Still a fair amount of disagreement in the models this far out so
specific details will need some time to get worked out.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Weather Advisory 125.
         Wind Chill Advisory 155.
MARINE...Storms 130 178.
         Gales 120 131 132 136-139 150 155 160 165 170-177 179-181 185
         Heavy Freezing Spray 130 139 140 160 180 185.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...KH
SOUTHCENTRAL ALASKA...BC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...JA/AH
MARINE/LONG TERM...KVP