149
FXAK68 PAFC 190044
AFDAFC
Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
444 PM AKDT Fri Apr 18 2025
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)...
A broad upper-level trough is slowly sliding eastward across
Southcentral this afternoon. Two shortwaves embedded in the
longwave trough continue to bring widespread shower activity to
portions of Southcentral. The first is over Price William Sound
with a weak surface low spinning near Middleton Island. The second
shortwave is sliding across the Susitna Valley and northern Cook
Inlet. The bulk of the shower activity is underneath these waves,
with one band of showers lifting from Kenai to Talkeetna and the
second lifting from Middleton Island into Cordova, Valdez, and the
Chugach Mountains. The airmass underneath the trough remains
quite unstable, helping to support the shower activity and
allowing for some heavier showers to develop in conjunction with
daytime heating.
On Saturday, drier weather and with more breaks of sunshine looks
to be on tap as a shortwave ridge attempts to build in to the
west, kicking the longwave trough to the east. An elongated
shortwave will ride overtop the building ridge and dig down over
the Copper River Basin, however, likely leading to some scatterers
showers for the region and higher elevations of the Talkeetnas.
Any respite in the clouds and shower activity will be short-lived
though, as an occluded front moves into Kodiak Sunday morning and
then into the Kenai Peninsula late Sunday. While inland areas may
be somewhat downsloped, the southeasterly winds aloft aren`t
overly impressive, so rain, however light, will likely spill over
into Anchorage and the Mat-Su Valleys on Monday. Snow levels for
this system are expected to be between 800ft and 1500 ft, with the
higher values towards Homer and Seward.
TM/CJ
&&
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (Days
1 through 3: Today through Monday)...
Currently, what is left of the surface low that has moved across
Southwest AK continues to dissipate and move eastward. This has
left behind short-lived isolated flurries, snow showers, and low
cloud ceilings, especially east of Bethel and north of Iliamna.
Surface high pressure situated across Bristol Bay is quickly
moving in behind the low, and will cause conditions to improve
overnight and Saturday morning.
Looking out west to the Western Aleutians, a weak area of low
pressure centered around Amchitka and Adak Station on Saturday
morning will increase precipitation chances and wind speeds to
some extent. Southerly winds will likely cause this push of
precipitation to fall as rain as surface temperatures will be
near 40F with not much colder air aloft. By Saturday night, this
low makes a run towards the Pribilof Islands as its attendant
front pushes through the Central and Eastern Aleutians with
rainfall and elevated winds. The Pribilofs may initially stay
just cold enough to allow snow to mix in before warm air advection
from a stout southerly flow kicks in and transitions precipitation
to rain. This will be a similar story during the day Sunday for
Nunivak Island and the Kuskokwim Delta as the system moves
northeastward. The only difference is that snow could hang on
longer, resulting in light 1-2" accumulations before a changeover
to a rain/snow mix. At the same time, the associated front moves
into the AK PEN and interior Southwest and is mostly a rainmaker.
By Sunday afternoon, the GFS shows a broad, complex low situating
itself across the Bering Sea and sending waves of precipitation
once again to the Pribilofs. There is above average model timing
and placement uncertainty with this low and any smaller waves
associated with it that may affect the Aleutians.
-AM
&&
.LONG TERM FORECAST (Days 4 through 7/Tuesday through Friday)...
An expansive and somewhat complex upper level low stretches
across the region through the forecast period. The main low center
over the Eastern Bering tracks across the Gulf of Alaska before
dissipating Friday. In the West, a second low center crosses the
Western Aleutians to take up station over the Central Aleutians
for Friday. A number of shortwaves rotate around both centers
during the forecast. A forecast blend with mostly ECMWF influence
combines with the GFS to carry strengths and tracks, while the
largest uncertainty remains with the minor details.
A Central Bering surface low extends a front across the Southern
Alaska Peninsula on Tuesday. Snow occurs across the NOrthern
Bering with Rain or rain and snow mixed over the AKPEN. A second
surface low picks up the main rainfall area, spreading it across
Kodiak Island into the Gulf of Alaska, diminishing Thursday. Areas
of moderate rain are expected through midweek over the Western
Gulf, and lingering near Kodiak Island through Friday. Over the
Western Aleutians and Bering, a strong North Pacific low brings
locally heavy rain, continuing over the Central Aleutians and
Bering into the AKPEN and Southwest Alaska through Friday. Most of
Interior Alaska will remain under quiet weather conditions.
- Kutz
&&
.AVIATION...
PANC...VFR conditions and light winds will persist.
&&
$$
147
FXAK69 PAFG 182120
AFDAFG
Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
120 PM AKDT Fri Apr 18 2025
.SYNOPSIS...
Blizzard conditions along the Arctic Coast improve today as winds
diminish this afternoon. Scattered rain and snow showers
throughout the Interior will help keep temperatures cooler today
than yesterday. The south slopes of the Brooks Range, particularly
along the Dalton Highway through Atigun Pass, will see 3 to 6
inches of snow accumulations through Sunday night. Conditions
become generally quiet after Sunday.
&&
.KEY WEATHER MESSAGES...
Central and Eastern Interior...
- Temperatures cool today and Saturday with highs in the low to
mid 40s today and highs in the mid 30s to low 40s Saturday.
Temperatures warm Sunday with highs in the upper 30s to mid 40s
and stay in this range through midweek next week.
- Mostly cloudy conditions with intermittent rain or snow showers,
especially in the afternoons. Showers diminish from the west
Saturday and Saturday night with only the Yukon Uplands and
southeastern Brooks Range seeing showers Sunday.
West Coast and Western Interior...
- A frontal boundary remains parked from Chukchi Sea coast through
the central Seward Peninsula to the Yukon Delta. West of the
front, mostly snow is falling while mostly rain is falling east
of the front. The front slowly moves east and weakens through
Saturday night and will be over the Western Interior tonight and
eastern Interior Saturday afternoon.
- Winds have shifted west/southwest behind the front as it moves
east. Wind speeds will continue to decrease through Saturday as
the front moves further east and weakens.
- High temperatures will be mainly in the 20s along the coast and
in the 30s inland.
- Showers return to the Yukon Delta Sunday evening as the next
system approaches. Showers stretch north to the southern Seward
Peninsula and St. Lawrence Island by Monday morning. Showers are
expected to be a messy rain/snow mix but with significantly less
accumulations than the previous system.
North Slope and Brooks Range..
- Blizzard conditions are improving this evening as winds
diminish. A Blizzard Warning is in effect through this evening
with strong easterly winds with gusts up to 40 mph and some
light snow showers and recent snowfall creating areas of blowing
snow reducing visibility to as low as a quarter mile at times.
- Snow showers continue along the south slopes of the Brooks Range
and north to around Toolik Lake along the Dalton Highway. Most
areas can expect 3 to 6 inches through Sunday night.
- Temperatures will be steady between 0 and 10 above near the
coast and in the teens and 20s in the Brooks Range.
&&
.FORECAST ANALYSIS AND DISCUSSION...
A front stretching from the Chukchi Sea Coast through the eastern
Seward Peninsula and into the Lower Yukon Valley is slowly moving
east and weakening as the upper level and surface lows that are
supporting it fill in. This process happens rapidly and causes the
organized body of the front to fall apart Saturday as it`s remnant
energy and moisture continues to support scattered showers across
the Interior. A 533 dam upper level high in the high Arctic and a
weak ridge that builds in the Gulf of Alaska as the low in the
Gulf moves east Saturday help to increase surface pressure in the
Interior to clear out the showers from the western and central
Interior by Sunday. Two lows move into the southwestern Bering Sea
Saturday and rotate around each other with the eastern of these
lows becoming a shortwave rotating around the western low. This
shortwave rotates into YK Delta and brings more messy showers to
the Yukon Delta Sunday afternoon with wet snow, sleet, and rain
likely. Accumulations will be generally less than an inch of
heavy, wet snow, but some areas further south may see up to two
inches of this wet, heavy snow. These showers will stretch into
the southern Seward Peninsula and to St. Lawrence Island by Monday
morning bringing very light accumulations of wet snow with sleet
and rain being less likely. These showers will move east into the
eastern Norton Sound and into the lower Yukon Valley as the main
low moves east to over St. Matthew Island by Monday afternoon
before being pulled south into the Gulf of Alaska by better
dynamics allowing a smaller shortwave feature to rapidly
strengthen into the new main low and pull the rest of the system
into the Gulf to end these showers.
&&
.EXTENDED FORECAST DAYS 4-7...
The Arctic high persists through the week and strengthens into a
1040 to 1045 mb high with models disagreeing on its exact
placement, but all pulling it further south. Another low moves
through the southern Bering Sea and into the Gulf of Alaska
Wednesday through Friday providing some more scattered showers to
the YK Delta and lower Yukon. Models agree fairly well on this low
with the exception of the Canadian, which closes the low off in
the Bering Sea and keeps it from entering the Gulf of Alaska.
Other models favor bringing the low into the Gulf leaving the West
Coast generally dry, but if the Canadian solution proves correct
then we`ll see more messy mixed showers in the YK Delta and
southern Seward Peninsula.
Coastal Hazard Potential Days 3 and 4...None
&&
.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Blizzard Warning for AKZ802>805.
PK...Heavy Freezing Spray Warning for PKZ805.
Brisk Wind Advisory for PKZ812.
Brisk Wind Advisory for PKZ813>815-858-859.
Brisk Wind Advisory for PKZ857.
Brisk Wind Advisory for PKZ860.
Brisk Wind Advisory for PKZ861.
&&
$$
Stokes
371
FXAK67 PAJK 182246
AFDAJK
Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
246 PM AKDT Fri Apr 18 2025
.SHORT TERM...Not as much to write about for the short term, with
the main takeaways being a diminishing trend of showers, clearing
skies and lighter winds Saturday, and widespread fog development
Saturday night.
Currently, a weak shortwave trough is passing over the southern
panhandle, slightly increasing winds in the southern panhandle and
bringing additional showers. Not expecting huge accumulations, as
water vapor GOES satellite products show a lack of significant
moisture over the area. Therefore, expect most places to at least
get wet, but west facing mountains to have increased rain totals
up to around a quarter of an inch through tonight.
As for tomorrow, expect showers to decrease in frequency from
north to south, with a high likelihood of seeing some blue in the
sky. Northwesterly flow aloft and downward motion in the 850-500
mb layer look to keep winds light on Saturday. With recent showers
and lack of sufficient drying, in combination with fast
temperatures drops from clearing skies and lighter winds,
expecting fog.
.LONG TERM...Early Sunday the broad Rossby Wave that pampered us
with abnormally wet/windy weather Friday will be departing into
Canada, with a region of subsiding air associated with confluence
aloft and negative vorticity advection upstream of the 500mb
trough axis moving over the Panhandle. With the lack of any tight
surface pressure gradient, expecting winds to be relatively light;
fresh to moderate breezes. Primary threat will be redevelopment
of fog Sunday morning across the interior communities and a
shallow cloud deck along the coast. Skies clear through Sunday
afternoon, shaping up to be an excellent day. As we get a taste of
summer, a closed low will be weakening while transiting the
Aleutian Arc, bringing onshore flow and rain from an occluding
front over the Panhandle into Monday/Tuesday. Expect easterly
winds to freshen up to strong breezes along Cape Suckling.
An additional focus in the mid-range is the redevelopment of a
surface low as the parent system digs into the Gulf Wednesday.
Some deterministic models are consistently placing gale force
winds, something to keep an eye on for mariners planning the Cross
Sound- Prince Williams transit. Current forecast published this
afternoon reflects confidence toward sustained easterly near-gales
forming Wednesday.
&&
.AVIATION...Showers continue this afternoon across the panhandle bringing
MVFR to IFR conditions during these showers. Elsewhere, MVFR to
VFR conditions continue with some areas even seeing mostly clear
skies near the Dixon Entrance. These showers are expected to
persist this evening as onshore flow continues across the
panhandle before starting to diminish starting in the north during
the early morning and spreading farther south during the mid to
late morning. Some lowered ceilings will still possible with
patches of clouds moving over the panhandle.
&&
.MARINE...Fresh to strong westerly breezes will continue in the
outer waters from Dixon Entrance up to around Cape Edgecombe.
These sustained winds will keep wave heights relatively high,
around 8-10 ft through the day Saturday. Expect winds in the gulf
to begin to diminish overnight tonight from north to south, and
seas to follow Saturday afternoon into evening again, from north
to south.
For the inside waters, predominantly westerly flow aloft with
pressures in the west trending up has prompted longer duration
westerly flow. Main areas of impact are east west facing channels,
such as Sumner Strait and the southern entrance of Chatham Strait.
Expect these conditions to continue to diminish overnight and
become mostly light air Saturday. Fog development in calm
conditions is likely Saturday night for inner channel areas no
including Lynn Canal and Clarence Strait. Expecting to see these
areas be around a light breeze, raising up fog to become a low
stratus deck.
&&
.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ012-022-053-641>644-651-652-661>664-
671-672.
&&
$$
SHORT TERM...NC
LONG TERM....AP
AVIATION...SF
MARINE...NCVisit us at http://www.weather.gov/Juneau
