Graphical Hydro Meteorological Discussion

000
FXAK68 PAFC 061353
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
453 AM AKST Mon Feb 6 2023

.ANALYSIS AND UPPER LEVELS...

A strong low pressure system moving north across the Kenai
Peninsula is spreading snow over Prince William Sound and into
Bristol Bay. Bands of moderate to heavy snow have developed from
southern Cook Inlet to Homer and Seldovia this morning. Elevated
winds reaching high end gales continue around the low and also
with the front lifting toward the north gulf coast. A transient
ridge over the Alaska mainland meanwhile is providing quieter
weather for Southcentral with mid to high clouds passing overhead.
Out west, a complex low with multiple low centers is slowly
weakening and moving east. Colder air on the backside of the low
is aiding gusty northerly winds and convective snow showers over
the Bering Sea and Aleutian Chain.

&&

.MODEL DISCUSSION...

Model guidance is in good agreement with the placement and
intensity of synoptic scale features at both the surface and in
the upper levels. As the aforementioned low weakens and winds
shift southwesterly, a chance of snow returns to Southcentral
today. Forecast confidence is high for snow coverage across the
Anchorage Bowl and Mat- Su Valleys lasting through early Tuesday.

&&

.AVIATION...
PANC...Light winds will increase to southerly 10 kts with a brief
gust to 18 kts around 06th/14z. Snow will increase in coverage
with MVFR to IFR conditions from 06th/16z to 07th/03z. Vicinity
snow showers continues after 07th/03z.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3:
Monday through Wednesday night)...

The well-advertised low is pushing onshore this morning, just west
of Seward. While colder air continues to wrap around the now
occluded low, a southerly flow near the surface has advected
enough warm air along the immediate coast east of the low center
to allow for a mix of rain and snow for Seward, Whittier, and
Portage. As the low continue to track inland and weaken, this flow
is expected to wane, allowing for a transition back to all snow.

On the backside of the low, however, enough colder air wrapping
around the center of circulation to allow for all snow across Cook
Inlet and Kachemak Bay. Deformation and instability along the mid
level trough west of the surface low is allowing for bands of
moderate to heavy snow to set up across Kachemak Bay this morning.
These bands will persist as they lift northward with the low
today, eventually overspreading the rest of the western Kenai
Peninsula, Anchorage Bowl, and Mat-Su Valleys. For areas around
Homer, a developing gusty southwesterly wind may also result in
some blowing snow, especially across the Homer Bluffs where the
resultant flow should allow for additional upslope snow.

As the low moves north, convergence in the southwesterly flow up
Cook Inlet and southeasterly flow through Turnagain Arm is
expected to develop. This may help enhance snow across the
Anchorage Bowl, especially across southern and western portions of
the Bowl. The development of a weak trough, along with an upper-
level wave and southwesterly flow, will also allow for widespread
snow to develop across the Susitna Valley this afternoon. Here,
snow may linger through Tuesday morning, especially in favored
upslope areas north and west of Talkeetna. Snow amounts of 1-3
inches are possible across the Matanuska and southern Susitna
Valleys with 2-4 inches, with locally higher amounts at elevation,
are possible across Anchorage. 3-5 inches of snow are possible
around Talkeetna with 6 to 10 inches of snow possible in the far
northern portion of the Susitna Valley.

For other areas, the southerly flow will result in continued
snowfall for the coastal mountains, as well as Valdez and
Cordova. However, with temperatures pushing into the mid 30s, rain
may mix in at times for Cordova. Southerly winds will be on the
increase across the Copper River Basin today as the low and its
decaying front move inland.

The widespread snow will taper off for Tuesday. However, weak
upper-level waves will continue to move north from the Gulf of
Alaska into Southcentral. This will result in scattered snow
showers, mainly along the southern half of the region. A weak area
of low pressure may move into Prince William Sound by Wednesday
morning with more widespread light snow for the Cook Inlet region.


&&

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

Broad longwave trough pattern lingers over Southwest Alaska,
slowly meandering eastward over the next couple of days.
Bristol Bay will stay light and showery with reduced visibilities
through the morning hours, with improving conditions into the
later afternoon hours. Snow chances will diminish but low stratus
clouds are expected to persist. Cold air wraps around the back
side of the trough, temperatures will continue to gradually drop
tonight through Tuesday night.

&&

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

Northerly flow stretches across the Bering Sea. Cold air advection
will help enhance winds to small craft in some areas, with a band
of gale force winds across the Central Aleutians today. Heavy
freezing spray will continue to spread northern and eastern
Bering, nearing the Pribilof Island waters today. Extreme freezing
spray will be an issue along the ice edge as well over the next
couple of days. Light lingering snow showers will continue across
the Aleutian Chain and southern Alaska Peninsula through Tuesday.

&&

.LONG TERM FORECAST (Days 4 through 7: Thursday through Sunday)...

Confidence continues to remain high on both domains remaining
rather active with no real sustained quiet stretches with high
pressure firmly in control, but rather transient ridges between
systems; the only exception might be coastal southwest Alaska.
Southern Alaska still remains under the influence of a broad
negatively trough. Expect more precipitation for the eastern
Kenai Peninsula, Prince William Sound, the northern Gulf Coast, as
well as interior southwest Alaska. The western Kenai Peninsula,
Anchorage, Mat-Su Valleys, and Copper River Basin could also see
precipitation chances during the first half of the longterm as
well, but uncertainty exists with potential cross barrier flow
issues. The models converge on the idea of a return to unsettled
weather as a deep Bering Sea low sends multiple fronts and
shortwaves eastward into the coast through at least Saturday. By
Sunday, there is a lot of model divergence at the surface, but the
consensus is that the longwave trough will continue to influence
the region.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Storm Warning: 120
Gale Warning: 119, 125, 131, 172, 175, 176, 351
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...MF
SOUTHCENTRAL ALASKA...TM
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...KM
LONG TERM...PJS

000
FXAK69 PAFG 061316
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
416 AM AKST Mon Feb 6 2023

.SYNOPSIS...
A few flurries around the Interior with partly to mostly cloudy
skies. Winds have been gusty from Indian Mountain to Tanana and
northeast in the higher elevations and especially along the Dalton
Highway Summits. There has been some blowing snow around and this
will continue through about noon today before the winds subside
and light snow settles in overhead. Along the West Coast, light
snow showers and blowing snow will persist from Wales to St.
Lawrence Island through Tuesday Morning. Otherwise, a persistent
high has kept it frigid along the North Slope with windy
conditions along the Northwest Arctic Coast resulting in
dangerously cold wind chills, but the wind will decrease through
today lessening the wind chills though still remaining cold.

&&

.DISCUSSION...

Upper Levels and Analysis...
Weak ridging in the interior extending southeast into Canada with
a 501 dam low over Eastern Siberia and a weak trough axis over the
North Slope. A 500 dam low over the Southeastern Bering with
troughing into the northern Gulf of Alaska. A ridge over the High
Arctic which has been there since last week is loosening its grip
slightly as it weakens north of Siberia.

Model Discussion...
Overall, models are in fairly good agreement with the upcoming
synoptic pattern both at the surface and aloft. A front moving
through the Interior will station itself north and west of
Fairbanks from Holy Cross to Tanana and northeast towards Fort
Yukon and Venetie with light snow this afternoon through Tuesday
midday before becoming less organized with snow showers around
through Wednesday morning. Light snow is becoming more likely for
Fairbanks and the surrounding area early Tuesday morning around
rush hour, though accumulations look to be light. Otherwise, a
couple of disturbances look to bring snow showers to the west
coast by Wednesday night and flurries may linger in the Interior
through Thursday morning.

Central and Eastern Interior...
Current gusty wind along the Dalton and Elliot Highway summits
will weaken during the day, so blowing snow will no longer be a
concern by this afternoon. A weak stationary front is moving
through the Interior with flurries possible from Fairbanks south
and east today. A band of light snow is expected to develop from
Tanana north and east towards Venetie this afternoon. Around 1-2
inches of snow is expected through Tuesday afternoon. As this
front pivots tonight, it will allow for a narrow window of
southwesterly flow to develop, meaning light snow is possible in
Fairbanks and the surrounding area beginning just after midnight
and continuing through the morning rush. The snow will be light
and we are expecting around and inch or less Tuesday morning from
Anderson to Chena Hot Springs and points north and east.
Additional flurries and light snow showers may be around at times
through midweek, though widespread accumulations aren`t expected
at this time. The next system on the horizon will come as a front
from the southeast which may bring light snow to the Interior
Thursday evening into Friday.

West Coast and Western Interior...
Gusty wind along the tip of the Seward Peninsula to St. Lawrence
Island will persist through Tuesday with areas of blowing snow,
especially near Wales and Tin City. Savoonga and Gamble may have
blowing snow at times though it shouldn`t significantly reduce
visibilities. Otherwise, a front will move into the Western
Interior this afternoon with snow mainly east of Unalakleet from
Holy Cross through Ruby. About 1-2 inches is expected through
midday Tuesday. By then, conditions will also be improving in the
Bering Strait with weakening wind and increasing visibility.
Otherwise, we will be looking towards Wednesday Night when a
decaying front moves east over the southern Bering Sea with a few
snow showers possible into Thursday morning from the Seward
Peninsula south.

North Slope and Brooks Range...
The Winter Storm Warning for the Northwest Arctic Coast has been
cancelled due to improving conditions and weakening winds. Wind
chills will be as cold as 45 below at times today, but with
weakening wind, wind chills should be moderating. Patchy fog will
be around on the Arctic Coast but the main story is continued
cold temperatures. There won`t be much moderation this week as we
expect high temperatures to remain in the mid 20s to 30 below,
especially east of Utqiagvik and lows will be in the 30s and 40s
below along the coast. Colder temperatures near 50 below zero will
continue in the Arctic Plains, especially around Umiat. For the
Brooks Range, mostly quiet weather will persist. East of Anaktuvuk
Pass tonight and tomorrow morning, we will be seeing some light
snow and snow showers with the steadiest snow being from Arctic
Village south and east. Snow accumulations will be light, around
1-2 inches or less through Wednesday.

Coastal Hazard Potential Days 3 and 4...None.

Extended Forecast for days 4 to 7...
Remaining cold along the North Slope with little moderation
expected. Along the West Coast, we were monitoring the potential
for a Bering Sea low to bring snow and wind on Friday, however the
trends are to bring the low south of the Aleutians which would not
bring many, if any impacts to Southwest Alaska. Otherwise in the
Interior, there may be some light snow and flurries around the
area Thursday, then we are monitoring a front from the southeast
which can bring more widespread light snow during the day on
Friday. This looks more like a nuisance than anything else.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Winter Weather Advisory for AKZ213.
Winter Weather Advisory for AKZ219-221.
Wind Advisory for AKZ223.
Wind Advisory for AKZ226.
PK...Brisk Wind Advisory for PKZ200.
Brisk Wind Advisory for PKZ201.
Brisk Wind Advisory for PKZ210.
Brisk Wind Advisory for PKZ220.
Gale Warning for PKZ225.
Brisk Wind Advisory for PKZ230.
&&

$$

Bianco

000
FXAK67 PAJK 061448
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
548 AM AKST Mon Feb 6 2023

.SHORT TERM.../Through Monday night/...Passing front has been
giving SE AK a wide range of weather overnight. The south has
been seeing, at times, moderate to heavy rain. The central and
northern areas have been seeing a wintry mix. But going forward,
the drier and colder air behind the front has the potential to
bring a pleasant Monday to the panhandle.

Overnight VIIRS and GOES satellite imagery is already showing the
clouds breaking apart over parts of the panhandle. Wouldn`t be
surprised if some folks end up with a mostly sunny day! But for
now, go into the day expecting partly to mostly cloudy skies.

The onshore flow and CAA should keep the rain and snow showers in
place over the area. The northern panhandle looks to see the bulk
of the showers, so kept higher PoPS in the north today with the
higher PoPS sliding southwards tonight.

Wind speeds should be on the downward trend for the most part
with the exception of Lynn Canal, where speeds will be around 25
knots through tonight.

.LONG TERM...Snow and rain showers are in the forecast through
midweek with cold air advection and onshore flow in place. A
stronger system is expected to move in from the south early
Thursday into Friday bringing the next dose of rain, snow, and
wind.

Regarding the showers through midweek, temperatures are expected
to be cool enough to support some areas of accumulating snow from
Petersburg northward and for higher terrain, especially under the
most persistent showers. This far out, models struggle with the
details of any mesoscale features that might focus the
precipitation, and this will be monitored as we enter shower
mode. Stay tuned to the forecast for updates.

Regarding the storm for the second half of the week, operational
models still show differences in the placement of the surface low
pressure, but there is agreement that at least a gale force front
will approach the Panhandle from the south late Wednesday night.
The Extreme Forecast Index is highlighting the Prince of Wales
and Ketchikan areas for wind potential, so increased the wind
forecast for these regions to strong wind criteria (40-55mph)
gusts Thursday. Also increased the wind forecast for Clarence
Strait and Cape Decision areas to include gales. Moderate
precipitation is likely with this system as well, with southern
areas starting as a snow or rain/snow mix and transitioning to
rain quickly as the warm front advances. Areas north of a
Petersburg to Port Alexander line will see a longer period of
snow at the onset and accumulations warranting winter weather
highlights are possible. With the model spread of surface low
placement and potential drying ahead of the system, as well as a
lack of really cold air at the surface, kept forecast snow amounts
conservative for now. A secondary piece of energy is expected to
cross the Panhandle on Friday, bringing the potential for another
burst of wind along with a wind shift to the West. Ensemble
members show two possible solutions one north with the wave
crossing near Cross Sound, the other further south. More analysis
on this trailing energy will be done tomorrow, but the message is
that the wind and precipitation impacts could continue into
Friday morning before calming. Past this point, the active
weather continues with another front moving into the area from W
late Saturday or Sunday.

&&

.AVIATION...LLWS has been tapering off through the late night
period although MVFR with pockets of IFR expected to continue
through the morning before lifting somewhat into the afternoon.
We do expect to see scattered showers (mostly rain) working in
from the southwest in an area of somewhat drier midlevel air on
the south/southeast side of the main currently centered south of
Valdez. MVFR should prevail into the overnight.


&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Weather Advisory until 9 AM AKST this morning for AKZ318-
319.
Areal Flood Advisory until 1 PM AKST this afternoon for AKZ330.
MARINE...Small Craft Advisory for PKZ012-013-022-036-041>043-051>053.

&&

$$

SHORT TERM...GJS
LONG TERM...CC
AVIATION...JG

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