167
FXAK68 PAFC 010036
AFDAFC
Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
436 PM AKDT Wed Apr 30 2025
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)...
A low pressure system once over the northwestern Gulf of Alaska
has shifted north up the Cook Inlet inland. An occluded front
stretched across the northern Gulf Coast including Prince William
Sound communities will continue to see persistent rainfall this
evening. As the low pressure center shifts near Anchorage late
this afternoon, gusty winds will be drawn from the east out of
Turnagain Arm and potentially curl up into portions of the
Anchorage area. These gusty winds are expected to be short-lived
as the low center weakens tonight and shifts further north, with
winds winds weakening significantly and shifting northeasterly
after midnight. A similar gusty pattern is expected for the Palmer
area, with gusty winds coming out of the Knik River valley,
potentially lofting glacial silt and blowing dust this evening,
diminishing by midnight tonight. Gusty winds out of the Southeast
are also expected through the Copper River Valley including
Gulkana and Glennallen early tonight, diminishing similarly by
midnight tonight. Finally, strong easterly winds driven by a
barrier jet along the northern Gulf coast will diminish this
evening.
Starting tomorrow, a prolonged period of mild, unsettled weather
will continue, with calmer winds across the region, but prolonged
rainfall expected along the coast, and light showers possible for
inland locations through the remainder of the workweek. Areas at
elevation such as Thompson Pass may see periods of wet snowfall
along the roadway, however it is not expected to accumulate,
instead melt rapidly. Thursday evening, a low pressure system from
the northern Pacific is expected to swing up into the northern
Gulf, reinforcing the pattern in place. Anchorage, Western Kenai,
and Mat-Su valleys may see periods of light showers through the
remainder of the week, however downsloping off the mountains is
expected to mute much of the impacts observed.
-CL
&&
.SHORT TERM FORECAST SOUTHWEST ALASKA (through Saturday afternoon)...
A cold upper level system lingers over the southwest Mainland. The
convective nature of the rain is evident from the King Salmon
RADAR this afternoon, but no signs of lightning detected yet.
Model guidance continues to show weak instability from coastal
Bristol Bay northwestward into the Kuskokwim Delta through this
evening, and isolated lightning strike can not be ruled out. Small
hail and brief periods of heavy rain will be the main impacts.
The scenario for Thursday is nearly identical to today, however
the system overhead continues to weaken. Instability will be
mostly dependent on where gaps in the low level cloud cover
develop and allow for surface heating. In general, across the
southwest, expect partly to mostly cloudy conditions with
scattered rain showers and isolated thunderstorms. High
temperatures in the upper 40s to low 50s. On Friday a disturbance
and weak front from the Gulf of Alaska will bring rain to the
slopes of the Alaska/Aleutian range. The next system will be
transiting south of the Alaska Peninsula and largely not affecting
the mainland.
MTL
&&
.SHORT TERM FORECAST BERING SEA/ALEUTIANS (through Saturday
afternoon)...
Fairly quiet conditions across much of the Bering Sea as weak cold
advection produces snow showers over much of the area. Across much
of the Chain, temperatures are warm enough for rain showers. The
next system will again move west to east along or just south of
the Aleutians Thursday through Saturday. There will be some gale
force winds, mainly south of the central Aleutians. Adak and Atka
will likely see rain turning to snow as the system transits to the
south, becoming snow showers when the system passes on Saturday.
MTL
&&
.LONG TERM FORECAST (Days 4 through 7/Sunday through Wednesday)...
A rather active weather pattern sets up across the Southern
portions of Alaska through the forecast period. On the upper level
map, a closed low South of the Eastern Aleutians and Southern
Alaska Peninsula intensifies briefly as it moves into the Gulf of
Alaska late Monday into Tuesday. This low will then weaken as it
drifts out of the Gulf for Wednesday. A moderate ridge moving
across the Aleutians and Bering flattens out near the AKPEN by
Wednesday. Another closed low slips out of the Russian Far East
for Wednesday. A loose cluster of ECMWF and GFS deterministic
models work the major features through Tuesday before yielding to
ECMWF / GFS means for Wednesday. Considerable uncertainty rests in
the minor details throughout the forecast.
A well developed and intensifying surface low South of the AKPEN
gains its greatest strength passing Kodiak Island Tuesday. With
its front extending across the Gulf of Alaska, areas of moderate
rain spread across from the AKPEN and Kodiak Island to the
Southcentral coastal zones through Tuesday, diminishing Wednesday.
Some moderate snow is expected over the higher elevations of the
AKPEN and Southwest Alaska into Bristol Bay and Eastern Bering.
Heavy rain moves into Kodiak Island Sunday. A strong North Pacific
low and its front spreads moderate rain across the Western
Aleutians and Bering Tuesday, moving into the Central Aleutians
and Bering by midweek.
- Kutz
&&
.AVIATION...
PANC...VFR conditions are expected to persist. Strong
southeasterly winds are expected to develop by late afternoon
behind a low that will move across the Kenai Peninsula and into
the western Susitna Valley this afternoon and evening. With this
type of system, then onset of the southeasterly winds will
probably be fast and strong with gusts to 35 kt or higher possible for
an hour or two after the southeast winds start. After that they
should be more typical southeast winds with gusts closer to 25 kt.
These winds should then rapidly decrease and turn back to the
north around, or shortly after midnight tonight.
&&
$$
324
FXAK69 PAFG 302154
AFDAFG
Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
154 PM AKDT Wed Apr 30 2025
.SYNOPSIS...
A 994mb low in SW AK is bringing light rain and snow showers to
the West Coast this afternoon with little to no accumulation. A
front moves over the AK Range this afternoon with rain showers
expected in the White Mountains. Otherwise, isolated rain showers
continue to be a possibility in the Interior, especially
north/east of Fairbanks through Thursday night. Much greater
chance for rain and snow on Friday as a pretty strong front
provides southeast flow to the Interior. The North Slope remains
under the influence of a high pressure bringing stratus and fog.
&&
.KEY WEATHER MESSAGES...
Central and Eastern Interior...
- Gusty winds through the Alaska Range Passes continue to weaken.
Near Red Flag conditions near Delta Junction and Isabel Pass.
- Light rain and snow showers this afternoon and tonight in the
White Mtns.
- Heavier rain and snow becoming more likely on Friday.
- Potential for light snow accumulations in the higher terrain
north of Fairbanks above 1500 ft.
- If there are flakes in Fairbanks, expect wet surfaces.
- A lot of uncertainty with precipitation end time, may be
Saturday afternoon or night.
- Sunday is looking like the nicest day of the weekend.
- Temps remain around seasonal norms through this weekend.
West Coast and Western Interior...
- Light rain and snow showers mostly end this afternoon/evening.
- Isolated rain showers possible tomorrow morning into the
afternoon, most areas remain dry.
- Greater rain and elevation snow chances on Friday, especially in
the Interior.
- Temperatures remain around or slightly below seasonable norms
through this weekend.
North Slope and Brooks Range..
- Stratus and fog continues at times, especially overnight along
the coast.
- Patchy dense fog in Atigun/Anaktuvuk Passes possible each
morning with snow showers each afternoon.
- Greater risks for snow with light accumulations will be Friday
night through Saturday evening. A few inches of snow are possible,
especially in Atigun Pass.
&&
.FORECAST ANALYSIS AND DISCUSSION...
A 522 decameter low in SW Alaska is driving force for our weather
through the weekend. This is bringing southerly/southeast flow
into the Interior allowing for ridging to move from Canada into
the Interior. However, it is also bringing a weak front over the
Alaska Range which will dampen the ridge this afternoon and bring
chances for rain/snow showers in the Interior. From here, the low
in SW AK weakens to about 525 dam, and turns negatively tilted
providing strong southeast flow to the Interior. Accompanying the
southeast flow is the potential for a strong wave of energy which
could bring moderate rain to Interior valleys with elevation snow
above 1500 ft. Southeast flow persists through Saturday with
chances for rain and snow showers continuing. There will be a
chance for snow in Fairbanks, especially if the precipitation
begins overnight but it is more likely that precipitation remains
all rain. Otherwise, any precipitation may drift to the west and
bring rain/snow chances to the Western Interior as well on
Saturday. It will largely dry out from south to north Saturday
afternoon and overnight through. The North Slope will probably be
spared from this front as the high in the Arctic remains the
dominant force.
&&
.FIRE WEATHER...
Near Red Flag conditions today in Delta Junction and Isabel Pass.
Sustained southerly winds are diminishing this afternoon and will
be 15-25 mph in the Pass and around 10 to 20 mph in Delta
Junction. Minimum RH values may drop to 25-30% this afternoon as
well, but we do not anticipate much in the way of fire danger. Any
remaining fire weather concerns will be eliminated on Thursday as
southeast flow becomes dominant and brings and influx of clouds.
By Friday, we will be watching for widespread precipitation,
potentially a wetting rain (0.10 to 0.25") in Interior Valleys
with elevation snow above 1500ft. Below 1500ft, there is a 20%
chance to see over 0.25 inches of rain, but a 40-50% chance for at
least 0.10 inches. This precipitation may weaken and move west
into the Western Interior with chances for rain/snow as well. We
will be monitoring this closely as the pieces fall into place.
Nonetheless, it looks like scattered showers persist into Saturday
before the Interior dries out on Sunday.
&&
.EXTENDED FORECAST DAYS 4-7...
Generally quiet weather for Northern Alaska. High pressure remains
in the Arctic but does begin to drop south early next week, so
there may be an uptick in easterly winds along the Coast.
Otherwise, a low anchors itself in the Gulf of Alaska near or south
of Kodiak Island. This, combined with the high dropping south in
the Arctic may bring a couple of breezy and cool days, especially
in the Interior. After Tuesday, uncertainty is high as there will
be a low breaking down in the Gulf, a high trying to build in
from the east and Arctic troughs trying to move through all of
it. There are hints that ridging will win out late next week
resulting in a more "summer-like" pattern and even the chance for
our first thunderstorms in the Interior.
Coastal Hazard Potential Days 3 and 4...None
&&
.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Winter Weather Advisory for AKZ801.
PK...Small Craft Advisory for PKZ806-812-816-851.
Heavy Freezing Spray Warning for PKZ806-812-816-851.
Brisk Wind Advisory for PKZ807-814-815-817-854-856-858.
Gale Warning for PKZ811.
Brisk Wind Advisory for PKZ813.
Brisk Wind Advisory for PKZ850.
Gale Warning for PKZ857.
Brisk Wind Advisory for PKZ859.
Brisk Wind Advisory for PKZ860.
Brisk Wind Advisory for PKZ861.
&&
$$
125
FXAK67 PAJK 302340
AFDAJK
Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
340 PM AKDT Wed Apr 30 2025
.SHORT TERM...Wet and windy short term with a plume of moisture currently
directed at the Yakutat area will be shifting eastward over the next
12 hours. Expect a strengthening of both winds and precipitation as
it moves eastward, as a shortwave trough moves up along the plume of
moisture. Gusts exceeding 30 mph for most land locations will begin
tomorrow morning, coinciding with periods of moderate to heavy rain.
For more information regarding hydrology, see hydrology section. The
bulk of the front will move through the panhandle tomorrow night,
but exact timing of frontal passage is lower confidence. Model
guidance are fluxing between 4 PM and 10 PM for when the front will
finally push through the panhandle and shift winds. Main determining
factor will be how fast the front will be able to break down the
ridging in British Columbia. Current solution represents the high
pressure breaking down slower, meaning heavier rain and winds
sticking around for longer.
.LONG TERM.../ Friday through Wednesday / A quick moving ridge is
is pushed east over the Eastern Gulf and Panhandle Friday and into
Saturday. Moving this along is the next incoming frontal band
associated with upper trough and moving in from the north pacific
and combining with a trough dropping SE from Eastern Russia over
the Bering. The upper level feature pulls up towards the Alaska
Peninsula, and the frontal sweeps across the gulf Sunday and into
the panhandle by Monday, bringing with it the organized band of
moisture and wind to start the week.
Upper level low will persist in the central gulf into the middle
of the week. This will lead to continued onshore flow and
shower activity for the panhandle.
&&
.AVIATION...Gale force front will continue to push into the
panhandle Wednesday night into Thursday, bringing moderate to
locally heavy precipitation and gusty winds. CIGs along the NE
coast will be AoB 1500ft with intermittent visibilities as low as
2SM in heavier showers from the primary moisture plume. For the
rest of the panhandle, conditions start out VFR and will
deteriorate later tonight as the main precipitation band and
elevated winds push inland. By Thursday morning expect elevated
winds, lowered VIS due to widespread precipitation and CIGs AoB
3500 ft. Main concern will be widespread LLWS for coastal and
southern TAF sites. Southeasterly LLWS around 1000 ft to 2000 ft
will peak for Yakutat this evening, while southern TAF sites of
Sitka, Klawock, and Ketchikan will see southeasterly LLWS build
through the evening hours and last into Thursday morning.
&&
.MARINE...Not much change to the overall marine forecast, expect for
Thursday night.
Outside: As advertised, latest ASCAT pass shows strong gales
right up along the coastline near Cape Suckling, around 45 knots.
While gusts are not calculated using this satellite product, it is
not a stretch to say gusts in that area are exceeding 50 knots,
prompting the earlier marine weather statement. No change for the
timing of gales along the gulf coast, nor major changes in the
15-20 ft seas.
Inside: For the inner channels, made some edits to Lynn Canal to keep winds
lighter for longer. Expecting a largely parallel gradient with
little directing flow aloft until at least Friday morning as an
upper level trough moves into Canada with rapid pressure rises
behind it beginning Thursday night. As the front moves through
tomorrow afternoon, with lower confidence on exact timing of the
frontal passage, wind directions will shift from southeast briefly
to south to southwest. Then, as pressures rise, fresh southerly
breezes to 20 knots will move up through Chatham Strait and Lynn
Canal.
&&
.HYDROLOGY...A wet 48 hours is expected for the entire panhandle as a
plume of moisture currently directed at Yakutat area will slight to
the east. MIRS rain rate product, displayed over the NE gulf coast,
show rain rates over Yakutat of around 0.25 in/hr. Upstream, an
embedded trough moving up along the plume will bring enhanced rain
rates to the rest of the panhandle beginning overnight and extending
through the morning hours Thursday. CIMSS MIMIC PW relative to
normal show an increasing plume currently around 250% of normal
racing up to the southern panhandle. What this will translate into
is heavy rain rates from Juneau to Ketchikan overnight tonight
through the morning hours Thursday, with rates possibly exceeding
0.2 inch per hour. Only expecting these rates to stick around for
around 6 hours as the front passes, but longer duration onshore flow
will ramp up totals more. Currently, Glacier Bay/Icy Strait area,
Juneau, and NE gulf coast including Yakutat appears to be the big
winners here in terms of totals. Over the next 24 hours, expecting
around 1.5 - 2.5 inches of rain, which are daily record amounts for
many places. While in fall time, this amount may not seem like much,
during late April, it is unusual to see this amount of rain
accumulation. Regardless, expecting soils to absorb most of the
rainfall associated with this system, meaning that river rises will
be dampened significantly. Therefore, rivers will rise, but are
expected to remain within bankfull conditions. No flooding is
expected.
&&
.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Strong Wind from 10 PM AKDT this evening through Thursday
morning for AKZ323.
MARINE...Gale Warning for PKZ036-641-642-651-652-661>664-671-672.
Small Craft Advisory for PKZ021-022-031>035-053-643-644.
&&
$$
SHORT TERM...NC
LONG TERM....Bezenek
AVIATION...STJ
MARINE...NC
HYDROLOGY...NC
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