094
FXAK68 PAFC 300041
AFDAFC
Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
441 PM AKDT Sat Jun 29 2024
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)...
A Bering Sea low is continuing to sink south with its front
pushing northward into the western Gulf and nearing Kodiak Island
by late tonight. Steady rainfall has already started. Models
consensus on total rainfall amounts differ quite a bit for Kodiak,
but on the low end Kodiak City could see a quarter inch through
Monday and up to an inch on the higher end. The expected total is
around three quarter inch or so through Sunday night. Kodiak could
start to see decreasing chances for rain Monday morning, though
the synoptic pattern will not change very much and chances for
showers will remain possible through the short term forecast for
Kodiak Island.
The upper ridge will start to build back into the central
interior of Alaska with ridge axis positioning itself along to
just north of the eastern Alaska Range by Sunday. Isolated
thunderstorms are possible along the slopes of the Alaska Range
and Wrangell Mountains Sunday, though models are hinting that a
low end instability axis might extend over towards the Talkeetna
Mountains and northern Susitna Valley Sunday afternoon.
With the Bering low and front to the south and west, and the
upper ridge building back west to the north...Southcentral will
see increasing easterly flow resulting in a more unsettled pattern
for the latter half of the weekend into early next week. Rain
showers will become more widespread overnight tonight into Sunday
morning for the northern Gulf as remnant lows in the eastern Gulf
become easterly waves. More widely scattered showers expected for
the Copper River Basin and northern Susitna Valley. The eastern
Kenai, Prince William Sound, and northern Gulf coast will see the
bulk of precipitation as the western Kenai, Anchorage Bowl, and
Mat-Su Valley will likely see downsloping set-up with lesser
chances for any showers. Chances for showers will gradually
decrease early Monday along the coast, but remain isolated to
scattered closer to terrain of the Susitna Valley and Copper River
Basin through Tuesday. Lastly, increasing pressure gradients
along the Gulf coast will result in gusty gap winds developing for
the Turnagain Arm and Copper Basin. The pressure gradient, and
therefore winds, could weaken Tuesday.
- PP / rux
&&
.SHORT TERM FORECAST SOUTHWEST ALASKA, THE BERING SEA/ALEUTIANS
(Days 1 through 3: Saturday night through Tuesday)...
A broad, longwave trough continues to sit over the Bering,
anchored by a vertically stacked low centered north of Atka.
Downstream of this feature, a shortwave trough and attendant
surface front are moving from the eastern Aleutians to the Alaska
Peninsula this evening. The result is continued widespread shower
activity stretching from coastal Bristol Bay north to the
Kuskokwim Delta. Southeasterly winds ahead of the front are gusty
along the Southwest coast this afternoon. Extensive cloud cover
over Southwest Alaska is also helping to keep temperatures on the
cooler side.
The aforementioned low will slowly slide southeast through
Sunday, bringing persistent showers to the eastern half of the
Aleutian Chain, as well as coastal Southwest Alaska. In the wake
of the low, gusty northwesterly winds are expected from west of
the Pribilofs south across the central Aleutians due, in part, to
increasing instability as colder air works in aloft.
A secondary upper-level wave will move over interior Southwest
Sunday. This feature will produce widespread showers for the
Middle Kuskokwim Valley. An isolated thunderstorm is also
possible; however, convective parameters are marginal at best.
By Sunday evening, a large amplitude ridge of high pressure will
build over the western Bering and push eastward through at least
the end of the forecast period. Widespread fog is likely
underneath the ridge as temperatures at the surface remain quite
cool but temperatures aloft (~850mb) warm to 10C or warmer. The
ridge axis, as well as the fog, moves east from the western Being
to the central Bering and Pribilof Islands for Monday and Tuesday.
-TM
&&
.LONG TERM FORECAST (Days 4 through 7)...
Low pressure will move eastward through the Gulf of Alaska through
the end of next week. Its eastward trek will be inhibited
by the ridge in the Copper River Basin/Southcentral through this
time. Isolated to scattered thunderstorms are possible in the
Copper River Basin toward the end of the week, too. Model
disparity of the low`s location and ridge`s westward progression
is high therefore, confidence in exact impacts and locations is
low. However, there remains high confidence that a ridge will
build into the Aleutians through the week.
-DJ
&&
.AVIATION...
PANC...VFR conditions with light wind will persist through
Saturday afternoon. Slightly strong southeast winds out of the
Turnagain Arm may brush ANC this evening, but confidence remains
low. General light and southerly winds are expected to prevail
this evening. Confidence is significantly higher that strong,
gusty southeast winds will increase in strength Sunday afternoon
and continue through through into early Sunday night.
&&
$$
927
FXAK69 PAFG 300859
AFDAFG
Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
1259 AM AKDT Sun Jun 30 2024
.SYNOPSIS...
Another hot day for the Interior today as temps reach into the mid
80 degree range. Smoke will continue to be hazardous to health
across parts of the Interior with poor smoke ventilation rates.
Monday, the ridge is weakening and west winds begin to ventilate
smoke off to the east which should result in some improvement.
Tuesday, southwest winds increase even more and temps slowly begin
falling as a major pattern shift begins toward breezier, cooler,
and eventually wetter conditions.
&&
.DISCUSSION...
Upper Levels and Analysis...
There is a 538 dam upper low centered over the E Aleutian Islands
with a building 569 dam ridge over the Interior of Alaska and
poking into the NW Arctic. There is a 528 dam arctic low over the
Beaufort Sea. There is a broad 1006 mb thermal trough situated
over the SE Interior. Weak high pressure is over the Arctic coast
with areas of stratus and fog.
Model Discussion...
Models are locked into the general pattern well into late week. We
prefer a NAM nest hi-res winds forecast with a blend to the NAM
and GFS models for the beginning of next week as a strong trough
moves across the NW Arctic, bringing winds and cooler temps.
Central and Eastern Interior...
Another hot and smoky day for much of the Interior as temps shoot
into the mid to upper 80s. Isolated thunderstorms will be possible
from Fairbanks south and east, with strong thunderstorms expected
over parts of the Alaska Range and SE Interior from Northway to
Eagle. Showers and some isolated thunderstorms will likely go all
night long along and near the AK Range. Monday, a pattern shift
begins with slightly cooler temps and increasing west to southwest
winds over the Interior, which will support more afternoon
thunderstorm chances from Fairbanks south and east. With a weak
northwest steering flow, some thunderstorms will form over the
hills and drift into the Fairbanks area. The westerly winds will
begin to ventilate smoke out of the Interior and it should
improve air quality somewhat. Tuesday is cooler again with breezy
westerly winds to 10 to 15 mph and thunderstorm threats generally
relegated to the higher elevations and over the E Interior.
West Coast and Western Interior...
Slowly warming temps through Monday, with a fairly good chance for
some stronger thunderstorms and heavy rain showers late today and
tonight from the W Alaska Range west to the YK Delta, as an
easterly wave moves across that area. Some storms may get fairly
close to the coast by Sun night. Otherwise, Monday is fairly quiet
with some isolated thunderstorms over the Interior and some
southwest winds in the afternoon. Tuesday, a fairly stout mid-
summer front will bring in broad southwest winds to near gale
force and rain from the Seward Peninsula north, with heavy rain
over the W Brooks Range. Expect 1-3 inches of rainfall over the
Chukchi coastal region and higher elevations.
North Slope and Brooks Range...
Isolated thunderstorms are again possible Sunday mainly over the E
Brooks Range, with some showers on Monday over the crest of the
range. Otherwise, weak high pressure along the coast will promote
periods of sun and stratus/fog at times, although it will not be
extremely widespread. Beginning Tuesday, a strong front
originating from E Siberia will plow across the entire region
bringing heavy rainfall and strong southwest winds 15 to 30 mph
with higher mountain gap winds.
Extended Forecast Days 4-7...
The big shift in the pattern is commencing Tue and continuing
through late week, as subtropical zonal flow pushes the ridge east
and replaces it with strong southwest winds and periods of
rainfall for the later week. This pattern will be a huge shift
from the hot and dry and smoky and will likely bring relief to
the Interior.
Coastal Hazard Potential Days 3 and 4...Strong southwest winds to
gale force will bring elevated water levels of 2 to 3 feet above
the normal high tideline from Norton Sound to the Chukchi coast
beginning Tue and lasting into late week.
&&
.FIRE WEATHER...
Hot and dry today with widely scattered to scattered thunderstorms
over the SE Interior, and isolated thunderstorms over the Interior
to Fairbanks and to the W Alaska Range. Temps are in the mid 80s
and min RH will be widespread mid to upper 20 % range. Winds will
be light from the north, so smoke will continue to be dense at
times. A batch of strong thunderstorms and wetting rains will
likely move across the W Alaska Range across the Kuskokwim Valley
and Kuskokwim Mtns to the Delta. The scattered thunderstorms over
the SE Interior are also very wet.
Monday, the flow becomes westerly near the surface with cooling
temps by 3 to 5 degrees and improving dense smoke conditions as
ventilation rates will increase. More afternoon isolated to widely
scattered thunder over the Interior higher elevation terrain, but
with a northwest steering flow, some storms will move south into
the Tanana Valley. Tuesday, southwest winds increase even more and
will get to near critical values over the N Interior, but will be
fairly breezy everywhere. Temps are falling again closer to
seasonal norms of mid to upper 70s. Only isolated thunderstorms
are expected Tue and those will favor higher elevations and the E
Interior. Wednesday will have fairly
&&
.HYDROLOGY...
Glacial fed rivers including the Tanana are slowly rising as
warming temperatures lead to increased high elevation snowmelt and
glacial melt.
Beginning next week around Wednesday, heavy rainfall will move
across the W Brooks Range with 2 -4 inches of rainfall through the
weekend, with 0.75 to 2 inches over parts of the Interior. Expect
river rises with this amount of water across the Mainland.
&&
.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Dense Smoke Advisory for AKZ834-837-839>844.
PK...None.
&&
$$
467
FXAK67 PAJK 292335
AFDAJK
Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
335 PM AKDT Sat Jun 29 2024
.SHORT TERM...Minor changes to the short term forecast at this
time as multiple weak shortwave troughs work around the periphery
of an upper level low situated near Haida Gwaii through Sunday.
Increased winds within inner channels, particular Lynn Canal,
through the rest of this afternoon as thermal gradient enhances
N/S flow with winds up to 15-20kts with an isolated gust up to
30mph possible. Frontal system has made slightly further
progression than anticipated with some light rain reaching the
surface via PAJN FAA Camera so slightly adjusted PoP chances
upward for the central and northern Panhandle through tonight.
Looking to tomorrow, anticipating the arrival of another shortwave
surface trough with bands of precip bringing isolated to
scattered showers across the panhandle. Highest precipitation
chances expected along the coast and along and south of a line
from Sitka to Angoon. Increasing cloud cover tonight over most of
the panhandle will keep minimum temperatures in the mid 50s. For
tomorrow, highs into the 60s across panhandle with isolated
locations in the northern panhandle breaking into the 70s if they
can make it out of cloud cover.
.LONG TERM...Little changes made to the long term forecast heading
through the middle of the week and the Independence Day holiday. A
weak frontal band from a decaying low will continue to bring
increased shower activity to the southern and central panhandle into
Monday before beginning to diminish. A ridge of high pressure will
build in from the south over the panhandle, leading to some skies
clearing by Wednesday for the inner channels. For the outer coast,
the transition to a more persistent WNW and overall onshore flow
will likely lead to marine layer clouds to push in on and off again,
which may lead to slightly lower daytime highs than communities
further inland. Overall maximum temperatures look to remain
seasonably warm ranging from the mid 60s to low 70s.
With the ridge building in, winds for the inner channels are set to
become more light and variable by Wednesday and into the later half
of the week, with the exception of local sea breeze effects such as
in northern Lynn Canal which may become more pronounced once skies
begin to clear out. For the gulf coast, modest winds of around 15 kt
are expected out of the NW as the ridge moves into position in the
eastern gulf before the gradient begins to slacken slightly.
Looking ahead to the Independence Day holiday, conditions look to be
fairly dry and warm Wednesday and on through Thursday morning. By
Thursday afternoon, model guidance begins to show signs of rain
returning to the panhandle from a system moving into the southern
gulf. Model spread is increasing during this timeframe though, so
there is lower forecaster confidence in terms of the timing of this
feature as well as the extent of its influence over the panhandle.
&&
.AVIATION...The marine layer is hanging tough over the south end
of Yakutat Bay and over the airport this afternoon with IFR CIGS
around 500 ft agl being reported there. We expect that layer to
sort of slip in and out of Yakutat into the evening with light seabreeze
out of the SW. Farther south, generally MVFR to VFR prevailing
over the central Panhandle, with IFR to MVFR CIGS and VSBYS in
rain being seen over the southern quarter of SEAK closer to the
decaying frontal boundary. For the next 24 hours, we expect the
more numerous coverage of showers to be along the outer coast
through this evening south of Cross Sound, with scattered showers
over the central inner channels. We expect any IFR conditions late
tonight into morning to be around Yakutat where the marine layer
is hanging along the coast, and for a few spots farther south near
the decaying boundary over the central Panhandle.
&&
.MARINE...A weak area of low pressure over the eastern Gulf of
Alaska will overspread intermittent rain over the panhandle
through Sunday. Anticipate elevated inner channel winds up to
15-20 kts and seas up to 2-3ft on Sunday afternoon within N/S
oriented channels as a weak trough pushes northward. General
drying trend moving into next week as a ridge of high pressure
becomes established over the Gulf of Alaska on Monday through
midweek.
&&
.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ661>663.
&&
$$
SHORT TERM...NM
LONG TERM....STJ
AVIATION.....JG
MARINE.......NM
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