Blizzard Warning 3, NWS Anchorage, AK

504 
WWAK42 PAFC 212055
WSWALU

URGENT - WINTER WEATHER MESSAGE
National Weather Service Anchorage AK
1255 PM AKDT Thu Mar 21 2019

AKZ155-212200-
/O.EXP.PAFC.BZ.W.0003.000000T0000Z-190321T2100Z/
Kuskokwim Delta-
Including the cities of Bethel, Hooper Bay, and Nunivak Island
1255 PM AKDT Thu Mar 21 2019

...BLIZZARD WARNING WILL EXPIRE AT 1 PM AKDT THIS AFTERNOON ALONG
THE COAST FROM TOKSOOK BAY NORTH...

Areas of blowing snow are expected to continue along the coast for
the next few hours, gradually improving thereafter.

$$

AKZ195-221000-
/O.CON.PAFC.WS.A.0004.190322T0900Z-190322T2000Z/
Pribilof Islands-
Including the city of Saint Paul
1255 PM AKDT Thu Mar 21 2019

...WINTER STORM WATCH REMAINS IN EFFECT FROM LATE TONIGHT THROUGH
FRIDAY MORNING THROUGH FRIDAY MORNING...

* WHAT...Blizzard conditions possible. Winds gusting as high as 
  50 mph could cause whiteout conditions in blowing snow. 
  Significant drifting of the snow is also possible. Total snow 
  accumulations of 2 to 4 inches are possible.

* WHERE...Pribilof Islands.

* WHEN...From late tonight through Friday morning.

* ADDITIONAL DETAILS...Travel could be very difficult to 
  impossible. Tree branches could fall.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Watch for blizzard conditions means there is a
potential for falling and/or blowing snow with strong winds and
extremely poor visibilities. This can lead to whiteout conditions
and make travel very hazardous.

&&

$$

http://www.weather.gov/afc

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
601 PM AKDT Wed Mar 20 2019

.ANALYSIS AND UPPER LEVELS...
The pattern aloft is anchored by two distinct longwave features.
A 513dm low pressure spins south of the eastern Aleutians, while
a 570dm high pressure sits over the Canadian Rockies. The
juxtaposition of these two features points the upper level jet,
and embedded disturbances toward Southcentral Alaska. The first
disturbance is making its way inland this afternoon, pushing a
front into the southwest Mainland. There are two Winter Weather
Advisories posted for this system, one for Bristol Bay (west of
the Nushagak River), one for the Kuskokwim Delta. The main concern
is blowing snow reducing visibilities. The overall flow pattern
brings a very warm air mass from the vicinity of the panhandle,
with 850mb temperatures this morning over the Gulf of +6C (they
have since cooled). The mixing of this air mass aloft to the
surface set a record high temperature at Cordova Airport(PACV) of
61 degrees this morning. Whittier Tunnel and Portage were also in
the mid 50s as well. The low level flow has ramped up across the
Gulf, bringing Turnagain Arm/higher elevation wind to the
Anchorage area.

&&

.MODEL DISCUSSION...
Synoptic agreement remains within the first 24 hours of the forecast.
No real differences with the leading system/front/disturbance.
There are some differences in how the Turnagain wind plays out
this evening, whether it continues to bend down-Inlet or comes
into town, or just grazes the airport. All three are in play as
far as high-res guidance is concerned. The following low pressure
system had differences in earlier runs, but seem to be coming into
agreement with how the front pivots into the Bering Sea and where
it sets up.

&&

.AVIATION...
PANC...VFR conditions and light winds will persist. There is some
uncertainty on what the Turnagain wind will do this evening. The
two most likely scenarios are the wind bending down-Inlet and
staying out of the airport, or just grazing the airport with some
light southeasterlies. It looks unlikely that a full-fledged gusty
Turnagain wind will impact the airport.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2: Tonight
through Friday)...

Heavy rain ongoing in Portage and Whittier this afternoon is
indicative of the intensity of the precipitation moving into the
coastal Kenai and Chugach mountains. With the heaviest precipitation
occurring over the rest of the afternoon and evening hours,
precipitation rates will diminish through the overnight as the
upper level support moves west into Southwest Alaska. Kenai radar
indicates that some of the heavier showers may be producing
precipitation downwind of the mountains, especially over the
western Kenai Peninsula, though the Kenai and Soldotna
precipitation gauges have not reported anything thus-far. For
Anchorage and points south, expect the potential for some
sprinkles through the evening. Further north in the Matanuska
and western Susitna Valleys, with less upper level support,
precipitation chances are lower. The Matanuska/Knik River Valley
and Turnagain Arm winds are all active this evening, and will
continue through the overnight. The drying effect of those winds
should help to keep any precipitation light and isolated.

On Thursday, most of the precipitation along the coast will shift
south and west, so Valdez and Cordova should spend at least the
second half of the day mostly dry. This is because a new front
moving north out of the southern Gulf will help to consolidate the
precipitation near it. Thus, in contrast to Valdez and Cordova,
it will be a very wet and windy day in Kodiak for much of the
day. The Turnagain Arm and Matanuska/Knik winds should persist for
most of the day, but should amount to just a breezy day with some
gusts from time to time. By Thursday night, the front moves north
into the North Gulf Coast with another round of heavy coastal rain
and mountain snow expected. This will also restrengthen the
Turnagain Arm and Matanuska/Knik Valley winds, but for Anchorage,
a predominant down-Inlet wind should keep the Turnagain Wind out
of town. On Friday, the front will stall out over Prince William
Sound, so the aforementioned winds will continue. Heavy rains are
possible along the front, which will be focused in the Whittier,
Valdez, and Cordova areas.

Other than precipitation and wind, the main weather story continues
to be unseasonably warm temperatures. Cordova broke 60 degrees
earlier this morning, while both Portage and Seward hit 50. These
kinds of springlike temperatures near record values will continue
for much of Southcentral for the foreseeable future as warm air
continues to be pumped northward. Happy Spring!

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 2/Tonight
through Friday)...
A warm front tracking northwest will continue to bring the threat
of snow and blowing snow to the Kuskokwim Delta through Thursday.
Gusty offshore northeasterly winds are expected to remain in
place over this time period. Confidence is generally high snow
totals of 2 to 4 inches for the Bethel area. As cold arctic air
interacts with the aforementioned warm front, brief freezing rain
is possible just out ahead of it roughly between Sleetmute and
Dillingham, though no ice accumulation is expected. Mixed
precipitation will transition to rain for most of southwest
Alaska on Thursday as the front moves offshore. A second low will
approach the AKPEN late Thursday into Friday, though as there will
not be any cold air leftover from the first system, it is
expected to be an all rain event.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 2/Tonight
through Friday)...
Northeasterly gales are expected west of Nunivak Island through
Thursday between a ridge over Siberia and a low over the western
Gulf. Snow ahead of the associated warm front will combine with
these stronger winds and bring the threat of blowing snow to the
Pribilof Islands later Thursday into Friday. Relatively light
winds and lower seas are expected for the Aleutians through
Thursday. Winds will gradually increase Friday from the Pribilofs
southward through Dutch Harbor as the low retrogrades westward
over the AKPEN. This will also bring light rain tracking east to
west over the Aleutians.

&&

.MARINE (Days 3 through 5/Saturday through Monday)...
For the Gulf of Alaska...southeast flow creating small craft to
gale force winds and elevated seas will continue into Saturday.
Winds should taper pretty quickly on Saturday. Models have a
tendency to calm winds a bit quickly, so we will watch the
forecast for winds and waves in the area. We have accounted for
this model bias in the forecast so we are confident in it, but
bears watching none the less. After Saturday, a brief break in the
weather is expected.

For the Bering Sea...Strong northerly flow is expected to continue
into Saturday, then gradually weaken to below small craft advisory
by the end of the day. A pattern shift is then expected to occur
Sunday with the first of a couple low pressure systems entering
the western Bering. This will switch winds to a southerly direction
and elevate winds speeds again. We are confident in the pattern
shift and elevated winds speeds, but the placement of the low and
strength of winds will need to be honed more in coming days.

&&

.LONG TERM FORECAST (Days 3 through 7/Saturday through Wednesday)...
The long term will start with the current pattern remaining in
place for Southcentral AK and low pressure in the western Bering
Sea. Lows will continue to train north into Southcentral AK until
Sunday. Conditions will vary slightly with the passage of each
low, but the common thread among them is warm, wet and windy
conditions through the weekend. Early next week it looks promising
for a break in the weather. Models are coming into agreement that
high pressure will arrive over the Gulf of Alaska and Southcentral,
finally breaking the trend of low pressure systems. While models
still differ on placement of the high pressure ridge, more of them
are coming into agreement. So, we have increasing confidence that
a pattern shift to quieter weather will occur.

Out in the Bering Sea, a series of lows will move through the
western and central Bering during the long term. A weaker low will
start the long term, followed by a strong and well organized low
moving north through the Bering Monday into Tuesday. A frontal
system from this low could work its way into Southwest Alaska. As
with Southcentral AK, there are differences in the long range
models with the weather in the Bering. However, they do agree a
strong low will move through, so we have confidence in this
pattern. It's just a question of how strong and exactly where the
low center will be located. This of course will affect the
forecast, so we will have to hone the details in the coming days.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Weather Advisory 155 161.
MARINE...Heavy Freezing Spray Warning 181 185.
         Gale Warning 119 120 125 130 131 132 136 137 138 139
 	                  150 170 172 173 174 179 180 181 185.
FIRE WEATHER...NONE.

&&

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