Gale Warning 648, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion...CORRECTED...
National Weather Service Anchorage AK
806 AM AKST Tue Nov 26 2019

.ANALYSIS AND UPPER LEVELS...

A strong upper level low is currently centered over Siberia.
Despite becoming vertically stacked, the associated surface low
has not significantly weakened yet and a front continues to track
west to east across the Aleutians bringing gusty southerly winds
and moderate to locally heavy rain extending from Adak through
the Pribilofs, with snow occurring over the Kuskokwim Delta. Cold
air remains in place farther east as an upper level ridge has
moved well into interior regions this morning. As such,
temperatures have fallen well into the single digits across much
of Southcentral and below zero in the Copper River Basin with
associated clear skies and light winds. With the relatively much
warmer temperatures in the Gulf, a strong pressure gradient is
building near the coast subsequently causing strong northerly
winds through terrain gaps.

&&

.MODEL DISCUSSION...

Models are in good agreement with regards to the front tracking
across the Kuskokwim Delta extending southwestward through the
Pribilofs and Aleutians. Latest models are gradually trending
towards a more westward solution with the next low moving in from
the North Pacific. This would lead to stronger southerly winds in
the Gulf and subsequent warmer temperatures across Southcentral.
Although confidence is growing, much uncertainty still exists.

&&

.AVIATION...

PANC...LIFR conditions will generally persist through mid-morning.
The fog is expected to slowly dissipate after sunrise and VFR
conditions will continue thereafter through Wednesday morning.
There is a slight chance of MVFR conditions this afternoon as snow
showers move across the terminal.

&&

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

The clearing overnight in Southcentral will be short lived as the
clouds from the next system are streaming across the Alaska Range
and into the region this morning.

The main change in the forecast is that the secondary low that will
develop south of the Alaska Peninsula tonight and then moves
northeast looks like it will track a little farther west. The result
from this movement is a generally warmer and windier forecast for
Southcentral. This should still bring in a heavy snowfall to the
Alaska Range, but the snow will turn to rain Wednesday night or
Thursday in the eastern Kenai Peninsula with this warmer forecast.

The Anchorage forecast is all about the wind direction. This has
been difficult one to discern as any southeast winds that make it
into the city out of Turnagain Arm will instantly jump
temperatures into the 40s. However, the gradient does look like the
winds should turn down Cook Inlet as they exit Turnagain Arm which
will keep the winds in town from the north to northeast and
therefore remain (just) below freezing Wednesday and Thursday. This
is a fine line and it is possible that the winds will mainly be
northeast, but west and Southwest Anchorage could see a brief switch
to Southeast especially on Thursday. The below freezing surface
temperatures with warmer air aloft also raises the possibility of
freezing rain. The most likely scenario keeps most precipitation
that does fall as snow (however not much) as the potential for no
precipitation due to downsloping is increasing. It is possible that
those southeast winds could come crashing into the city again like
last week and bring widespread 40 degree temperatures, but that
looks less likely at this time. This scenario will be re-evaluated
for the next forecast package.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Today
through Thanksgiving Day)...

The weather pattern across Southwest Alaska is expected to remain
very active over the next 3 days. Starting with the present, the
Coastal Flood Advisories remain in effect. The high tide that will
produce the greatest impacts is expected later on this morning.
Meanwhile the front that is rapidly scouring out the cold air in
place just 24 hours ago is causing precipitation over much of the
western half of Southwest Alaska. Areas that began as snow are
warming above freezing, with the changeover to rain already
through Hooper Bay. While it is still snowing in the Bethel area
currently, the changeover to rain should be within the next few
hours, as temperatures are already into the mid 30s, and should
continue warming through the day today. Coastal locations in
Bristol Bay are already above freezing with Dillingham starting
out as rain. The rain/snow line will continue to advance eastward
into portions of the southern and western Lower Kuskokwim Valley
today. Sleetmute and Sparrevohn may mix with rain at times, but
for the most part will remain snow.

The front is expected to stall out over the Kuskokwim Delta for
much of the day today, with rain as the main precipitation type.
For areas east of the Kuskokwim Mountains, the precipitation will
be much more intermittent today, and for the most part will be
rain across Bristol Bay and snow for the Lower Kuskokwim Valley. A
relative break in the precipitation in these areas are expected from
this afternoon through much of tonight, while rain continues in the
Kuskokwim Delta.

On Wednesday, a North Pacific low will move up along the stalled
out front into Southwest Alaska, reinvigorating the precipitation
east of the Kuskokwim Mountains from south to north through the
day. This will cause widespread rain and strong winds through the
Alaska Range gaps across Bristol Bay. These winds will move north
into the Lower Kuskokwim Valley as the parent low tracks north.
With cold air expected to remain on the back side of the low, much
of this occasionally heavy precipitation will fall as snow, with
amounts of 15 to 21 inches and locally higher amounts almost
everywhere east of the Kuskokwim Mountains. Thus, a Winter Storm
Watch has been issued for heavy snow that will be wind-swept as well
in the gusty winds. Temperatures hovering just below freezing will
make the snow wet, which in turn should prevent much drifting and
resuspension of freshly fallen snow. Thus, whiteout conditions are
expected to be the exception, not the rule. Nevertheless, the snow
could fall heavily enough at times to drop visibilities to a half
mile or less.

There is currently a very large discrepancy in the models as to
how Thanksgiving Day shapes up weatherwise. Cold air following
behind the Wednesday low on northerly winds will eventually bring
all areas of Southwest Alaska back below freezing, except along
the immediate coast of Bristol Bay. The question will be where a
zone of heavier precipitation sets up. In previous days, this was
expected to be over Southcentral and Thanksgiving was looking cold,
breezy, but dry for most of Southwest Alaska. Now, the models are
trending westward with that precipitation, and so the threat of snow
is increasing for Bristol Bay and the Lower Kuskokwim Valley. With
this portion of the event, if it happens, the precipitation type is
very likely to be all snow, as cold air will be in place on gusty
north winds throughout the event. This could result in a prolonged
period of light to moderate snow which could persist through much of
the day on Friday. In fact, one of the models that ends the snow for
most of Thanksgiving Day brings it back on Friday, though amounts
would be minimal as the zone of snow would be moving and much
weaker. Stay tuned to future updates as the details get ironed out
for Thanksgiving Day and beyond.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3: Today
through Thanksgiving Day)...

The front that essentially is dividing the Bering in two is slowly
moving east this morning. It's currently moving over Adak and
Atka, through the Pribilofs, and into the Kuskokwim Delta. As the
front continues pushing eastward today, snow showers are already
following behind it with clear skies in between the showers. This
Siberian cold air mass will overspread essentially the entire
Bering Sea by Wednesday night. Meanwhile a North Pacific low will
move over Bristol Bay on Wednesday morning into Southwest Alaska.
On Thanksgiving Day a new strong low will move into the Western
Bering and Aleutians, bringing gale force winds and rain to the
area as a warmer air mass also moves in.

&&

.MARINE (Days 3 through 5)...

Southerly gales are expected to spread from west to east across
the Bering and Aleutians Thursday and Friday as a front works its
way across the area. Northerly Gales are expected south of the
eastern Aleutians and Alaska Peninsula on Thursday and Friday with
strong inflow into a low over the southern Gulf.

&&

.LONG TERM FORECAST (Days 3 through 7)...
Shortwave energy initially over the eastern Aleutians/Bering Sea
into the North Pacific on Wednesday should progress eastward and
weaken while a mid-latitude system to the south remains separated
from most of this energy and eventually drops southeastward.
Toward the end of the week and weekend the pattern will become
more dominated by a deep upper low moving into or just inland from
the extreme western/northern Bering. The overall trough containing
the upper low should extend south into the mid-latitude Pacific,
with the trough axis most likely reaching the eastern Bering
around next Mon. Expect a downstream ridge aloft to cross the
mainland around Fri-Sat and continue into western Canada. For the
southern Alaskan mainland this will lead to a warming trend
Wednesday and Thursday, with warmer than normal temperatures
continuing through the weekend. Precipitation type will therefore be
an issue for most of the extended forecast.

Operational model runs and individual ensemble members display a
decent amount of spread and run-to-run variability to temper
confidence in the forecast, and thus it is a little below
average.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Storm Watch: 152.
Coastal Flood Advisory: 155 161.
MARINE...Gale Warning: 130-132 150 165 170 172 173 179-185 352 414.

&&

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

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1041 AM AKST TUE NOV 26 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1010 AM     SNOW             2 N BETHEL              60.79N 161.76W
11/26/2019  E2.0 INCH        BETHEL             AK   LAW ENFORCEMENT

            SPOTTER REPORTED 1-2 INCHES OF SNOWFALL
            BEFORE THE SNOW CHANGED TO RAIN EARLY THIS
            MORNING.

&&

ED

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1042 AM AKST TUE NOV 26 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1030 AM     SNOW             1 SSE SLEETMUTE         61.70N 157.17W
11/26/2019  E6.0 INCH        BETHEL             AK   PUBLIC

            SPOTTER ESTIMATED 5-6 INCHES OF SNOW.

&&

ED

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1043 AM AKST TUE NOV 26 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1040 AM     SNOW             1 W CHUATHBALUK         61.58N 159.25W
11/26/2019  E3.0 INCH        BETHEL             AK   PUBLIC

            SPOTTER ESTIMATED 3 INCHES OF SNOWFALL
            BEFORE THE SNOW CHANGED TO RAIN.

&&

ED

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1214 PM AKST TUE NOV 26 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0100 AM     FLOOD            1 SE HOOPER BAY         61.53N 166.09W
11/26/2019                   KUSILVAK           AK   LAW ENFORCEMENT

            SPOTTER REPORTED MINOR FLOODING LAST NIGHT
            IN HOOPER BAY. SAID THE FLOOD WATER EXTENDED
            FROM AIRPORT ROAD INTO THE TOWN CENTER BUT
            IT WAS NOT DEEP.

&&

ED

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
226 PM AKST TUE NOV 26 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1130 PM     FLOOD            2 ENE KIPNUK            59.94N 164.04W
11/25/2019                   BETHEL             AK   PUBLIC

            CORRECTS PREVIOUS FLOOD REPORT FROM 2 ENE
            KIPNUK. SPOTTER REPORTS MINOR FLOODING
            BEFORE MIDNIGHT.

&&

ED

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
227 PM AKST TUE NOV 26 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0226 PM     FLOOD            NEWTOK                  60.94N 164.64W
11/26/2019                   BETHEL             AK   EMERGENCY MNGR

            STATE EOC REPORTED FLOODING IN NEWTOK. SAID
            THE SEVERITY OF THE FLOODING IS UNKNOWN AT
            THE MOMENT.

&&

ED