000
FXAK68 PAFC 012350
AFDAFC
Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
350 PM AKDT Wed May 1 2024
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)...
Cloudy conditions will continue across Southcentral through the
end of the week and into this weekend as weak shortwaves move
through. A low exits the Bering Sea and moves into the southern
Gulf of Alaska on Thursday and its associated front pulls
moisture right towards Kodiak, eastern Kenai Peninsula, and
western Prince William Sound. The bulk of the precipitation will
be in the aforementioned areas for Thursday and Friday before
spreading eastward to include Cordova and Valdez by late Friday
night. The next system is taking a more southerly track and moving
a bit slower than shown in previous model runs that will delay
rainfall to Valdez and Cordova until at least late Friday night.
Additionally, easterly flow near Seward will help keep rain
lighter with lower amounts expected. Rain will be near continuous
for Kodiak Island through much of Thursday. Rainfall amounts in
Kodiak City should be around an inch to inch and a half, with
higher amounts in the mountains. Downsloping easterly flow will
keep the west side of the Peninsula and Anchorage largely dry.
Showery activity is possible today in portions of the Susitna
Valley and Copper River Basin but should remain light and brief.
&&
.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Today
through Friday night)...
A rapidly weakening low pressure system in the southeastern
Bering Sea continues to push a fairly weak frontal boundary into
Southwest Alaska this evening. Areas of light showers will persist
for the Bristol Bay region tonight before coming to an end
Thursday morning, as the parent low is absorbed by a stronger
incoming trough entering the western Bering tonight.
To the west, a new low pressure system is set to begin moving
over the western Aleutians by early this evening. The low will be
preluded by a front on the eastern leading edge. The front will
push quickly across the western-most Aleutians, reaching Adak by
late tonight/early Thursday morning. Initially, gale-force
southeasterly winds with light-to-moderate rainfall are expected
to be produced along the front, gradually weakening to sub-gale
and light rainfall by the time the front reaches Atka. By Thursday
afternoon, the front will have reached Nikolski, and the parent
low-pressure system will be entering the western Aleutians,
bringing another round of rainfall. The front and low will
continue advancing steadily across the Chain until the front
reaches Southwest Alaska by early Friday afternoon. Notably, as
the front crosses the Pribilof Islands late Thursday night/early
Friday morning, there is the chance for some of the early precipitation
to come down as a wet snow or a rain/snow mix. This is expected
to be brief, and accumulated snowfall would likely melt by Friday
afternoon. However, up to 2 inches of this wet snow is possible
before shifting to rainfall.
-CL
&&
.LONG TERM FORECAST (Days 4 through 7: Sunday through Wednesday)...
Active, but not overly impactful weather, is expected for the
long term forecast. Generally, expect widespread precipitation
for the Southern Mainland as an occluding low dissipates in the
northern Gulf. An upper low moving from the Arctic into the Bering
Sea will bring a cool down for Southwest Alaska early next week.
By the latter half of Monday, this upper low phases with another
low in the North Pacific, strengthening it as it moves towards the
Southern Mainland through midweek. However, model agreement
diminishes considerably around Monday, leading to lower confidence
in the evolution of this system.
Diving into the details... Sunday begins with a broad longwave trough
extending across much of Alaska. A vertically stacked low over
Southwest Alaska will gradually move into the northern Gulf
through Sunday. The low`s front will bring steady rain along the
north Gulf coast, with inland areas in Southwest and Southcentral
staying much drier due to downsloping. Instead, these inland
locations will likely see widespread showers due to robust
vorticity associated with this upper low, with the potential for
stronger convection Sunday afternoon and evening as an easterly
shortwave transits the Copper River Basin. Otherwise, expect
outflow winds to pick up Sunday across Alaska Peninsula and around
the Gulf.
By Monday, a rather compact upper level low slides south from the
Bering Strait into the Bering Sea, drawing down colder air for
Southwest Alaska. While a bit chillier than what we`re seeing now,
overnight lows remain relatively high at around 20-30 degrees for
Southwest Alaska. Precipitation generally tapers off across the
region on Monday as the Gulf low dissipates and moisture remains
relatively limited for the Bering Sea low.
By Tuesday, poorer model agreement leads to lower forecast
confidence. The main point of contention between models is how the
Bering upper low phases with an upper low moving towards the
Aleutians from the North Pacific. For the forecast, have leaned
towards the consensus where these two lows phase, leading to a
strengthened surface low with stronger winds and higher moisture
content as it moves towards the Southern Mainland for Wednesday.
The alternate scenario keeps the surface low weaker, with much
less impactful weather expected. Neither scenario looks
particularly hazardous, but we`ll continue to monitor trends and
refine forecast details in the coming days.
-KC
&&
.AVIATION...
PANC...VFR conditions will persist through the TAF period.
Southeasterly Turnagain Arm winds are expected to pick up again
this afternoon and move over the terminal before diminishing
tonight. Winds thereafter should remain light and become northerly
by Thursday morning.
&&
$$
000
FXAK69 PAFG 020039
AFDAFG
Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
439 PM AKDT Wed May 1 2024
.SYNOPSIS...
Models are in good agreement at least through Thursday showing
the upper trough over the Bearing Sea moving eastward towards the
Alaska Peninsula and eventually into the Gulf of Alaska by
Thursday afternoon. We will see increased southerly flow through
the Alaska Range that will bring Chinook winds that will lead to
some elevated fire weather concerns on Friday and continuing into
the weekend. This southerly flow will actually be reinforced by
another strong upper-level trough that moves through the Bering
Sea and into the Alaska Peninsula into the weekend.
&&
.DISCUSSION...
Frontal boundary moved through the Interior and now will see
a slow warm up in temps, warming back up into the 60s Friday
and Saturday. We will see some increasing Chinook winds along the
northern slopes of the Alaska Range. Because of this, wind prone
areas will see wind gusts increasing to around 30 to 50 mph,
especially into the weekend. With lower daytime humidity values,
this will lead to some elevated fire weather conditions from
Thursday and only increasing into the weekend. This will also
allow for some sort of WAA for the interior that will bring above
average high temperatures.
An Arctic cold front will generally continue to impact the North
Slope through late week. This will lead to cooler than normal
temperatures across the northern slope into the weekend. We will
also see periods of light snow, fog, and low stratus through at
least Friday. Winds will begin to increase as we head into the
weekend, with gusts up to around 30 mph that will likely bring more
periods of blowing snow.
West coast...Precip on the downtrend for Thursday before the
second upper-level trough moves into the Gulf of Alaska that will
bring another round of what looks to be more widespread showers to
the southern West Coast on Friday and into Saturday. Northerly
winds will ramp up in the Bering strait with gale-force winds
Thurs into Friday.
Coastal Hazard Potential Days 3 and 4...None.
&&
.FIRE WEATHER...
By Thursday, min RH values from Fairbanks into the Delta Junction
and the Eastern Alaska Range and the Upper Tanana Valley will be
in the 15 to 30 percent range. Mixing this with increasing
southerly winds through the Alaska Range passes fire weather
concerns will increase. Looks like moderate Chinook winds will
develop as early as Thursday afternoon, increasing as we move into
Friday and then continuing into the weekend. Wind gusts of 25 to
40 mph near Delta Junction and higher gusts near Isabel Pass and
lower humidity values will be very near Red Flag conditions for
the aforementioned areas.
&&
.HYDROLOGY...
An ice jam has formed 6 miles downstream of Manley and is causing
minor flooding at the community park along the slough. As of
midday Wednesday, the River Watch team reports that this jam does
not appear to be strong.
However, ice is still in place and looks strong at the jam point
which caused flooding in 2022. It is possible that when the jam
just down stream of Manley breaks, that it will form back up near
the 2022 location, but the flooding should not become much worse
than it is currently. When the jam finally releases and ice
flushes further down stream, river levels are expected to come
back down in the Manley area.
River Watch flew the Yukon River yesterday from Eagle to
FourtyMile River. An observer 23 miles upstream of Eagle said that
the Yukon there broke up yesterday afternoon. Ice began flowing
but within a few hours had stopped flowing and an ice jam formed.
Yukon rose to near mid-summer high levels and was continuing to
rise slowly. Due to current river levels and ice conditions, the
threat for flooding has diminished in the area around Eagle.
However, ice jams can still pose a localized threat in the areas
immediately around where they form.
&&
.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Flood Watch for AKZ846.
PK...Small Craft Advisory for PKZ806.
Heavy Freezing Spray Warning for PKZ806-816.
Brisk Wind Advisory for PKZ807-810-811-856-857.
Gale Warning for PKZ816.
Gale Warning for PKZ817.
Gale Warning for PKZ851.
Gale Warning for PKZ854.
&&
$$
000
FXAK67 PAJK 012255
AFDAJK
Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
255 PM AKDT Wed May 1 2024
.SHORT TERM...The pattern remains quiet through the end of the
week, as the steering flow continues to move systems S of the
panhandle. A lingering cloud deck over the central panhandle as of
Wednesday afternoon will continue to dissipate as it moves N. While
a marine layer may re-develop tonight, do not expect it to be
quite as widespread, given an anticipated wind shift to the SE
along the outer coastal waters as a system tries to enter the
gulf. Precipitation is unlikely to successfully reach the
panhandle - though some debris clouds Thursday and Friday can`t be
ruled out. For the panhandle, this means strong diurnal trends in
temperature, with high temperatures reaching into the 50s or even
60s, and low temperatures reaching into the 30s. Freeze advisories
have been issued for much of the Icy Strait Corridor as well as
Admiralty island, as the potential exists for temperatures to dip
below freezing in these areas.
Primary changes made to the short term forecast were the
strengthening of winds in the outer coastal waters Thursday and
Thursday night, along with bringing down low temperatures across
parts of the northern half of the panhandle. Made some minor
changes to sky cover for Thursday and Thursday night. Overall, the
forecast remains largely on track.
.LONG TERM.../ Thursday to Sunday night / Weak high pressure over
the eastern gulf and panhandle are holding in place through
Friday. A short wave will move from the southwestern gulf across
the southern gulf and southeast towards the Pacific Northwest by
Friday morning. A larger low moves into the Bering Sea Friday and
Saturday while drifting east. The associated frontal will move
into the panhandle area late Saturday, with main panhandle more
Sunday and continuing into early Monday. Widespread showers
behind the Sunday front will keep rain going into Monday.
&&
.AVIATION...Agreeable flying weather continues with light winds
and VFR over the majority of the region. Could see some areas of
MVFR CIGS in the south tonight, with MIFG for the morning at
PAKW.
&&
.MARINE...A developing marine layer in the NE gulf coast will
advect southward, bringing lower visibilities and some possible
drizzle. Currently, a modest amount of low clouds over the gulf
will descend, forming the basis for this marine layer. Expect for
this layer to infiltrate into Yakutat Bay Entrance and Cross
Sound, but not much further. During the morning on Tuesday, the
marine layer will retreat with continued high pressure over the
panhandle. Mostly light to 10 knot winds for the inner channels
with a northerly component. Lynn Canal is the exception, with
southerly winds, possibly increasing to 15-20 knots depending on
daytime heating in the north.
&&
.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Frost Advisory from 3 AM to 9 AM AKDT Thursday for AKZ317-
320>322-324-325.
MARINE...Small Craft Advisory for PKZ652-662>664-671-672.
&&
$$
SHORT TERM...GFS
LONG TERM....Bezenek
AVIATION...AP
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