000
FXAK68 PAFC 161244
AFDAFC
Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
444 AM AKDT Thu May 16 2024
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)...
A pattern shift is ongoing over Southcentral as the high amplitude
ridge over the Copper River Basin slowly retreats to the east and
a deep longwave trough over the Eastern Bering Sea and Western
Alaska slowly pushes to the east over the next several days.
Clouds cooler temperatures and increased chances for rain will
replace the warm and drier weather of the last couple days.
A front wrapping around a weak low pressure system pushing north
and east into the western Gulf of Alaska this morning and over
Kodiak Island this evening will bring an increase in clouds,
periods of light light rain into Kodiak Island and the Kenai
Peninsula this morning. The ridge over the Copper River Basin will
continue to slowly move to the east and as the low over the Gulf
of Alaska slows and weakens over the Northern Gulf of Alaska
today with precipitation holding off until this afternoon for the
Anchorage Bowl and MatSu areas. Cloud cover over the area will
shave a few degrees off of the high temperatures that we have seen
the last couple of days with the exception of the Copper River
Basin where clouds will hold off until this evening. Winds will
generally be light except for typical southerly gap wind locations
-CC
&&
.SHORT TERM FORECAST SOUTHWEST ALASKA, THE BERING SEA AND THE
ALEUTIANS (Days 1 through 3)...
The front associated with the weakening Kamchatka low continues to
drift eastward, producing rain and snow for much of Southwest.
This trend will continue through Friday afternoon before the
system dissipates. Additionally, a shortwave low is quickly
passing through the western and central Aleutians this morning,
providing a quick spurt of precipitation before it exits into the
North Pacific.
The next focus of attention will be the formation of an upper
level trough in the northern Bering starting Friday morning. The
trough will begin to swing southwards towards the eastern
Aleutians and Alaska Peninsula throughout the day Friday into
Saturday morning. Most of the eastern Bering will see
precipitation Friday afternoon through at least Saturday evening.
Some locations near the coastline across Southwest could also see
precipitation as the system treks southward. Colder air from the
Arctic will also be dragged down with this system, increasing the
potential for snow to occur at least in the morning hours of
Friday and Saturday. As the trough tilts near the AKPEN on Saturday,
increased southeasterly flow aloft and a tightening pressure
gradient will support increased winds across the region, as well
as stronger gap winds in areas like Kamishak gap. Models are still
struggling with the progression of the system, especially as the
trough tilts negatively over the AKPEN sometime on Saturday. With
that said, model guidance does agree broadly on the trend of how
this system will develop through the forecast period.
Lastly, a new shortwave trough will begin to impact the western
Aleutians and Bering starting Saturday afternoon. Small craft
force winds gusts are possible, and widespread precipitation
mainly in the form of rain is currently expected as the shortwave
moves eastward.
-BS
&&
.LONG TERM FORECAST (Days 4 through 7: Saturday through
Wednesday)...
The long-term period begins with an upper-level trough situated
over the Eastern Bering Sea and weak ridging over Southcentral and
the Central/Western Aleutians. This upper-level pattern will be
represented at the surface by a surface low in the Eastern Bering pushing
a broad frontal boundary into Southwest Alaska and the Alaska
Peninsula. At this time, Southcentral will likely be under the
influence of the ridge, this may manifest as more clear skies,
however the chance for a mid-level stratus deck is possible. By
Sunday morning however, the low is expected to track across the
AKPen, entering the Western Gulf of Alaska, spreading a
potentially heavy, but relatively brief, shot of rainfall across
coastal locations of Prince William Sound as well as Kodiak
Island. Model agreement up to this point in time is fair with some
slight variations, but the overall themes and timing represented
well throughout. By Sunday afternoon however model solutions
diverge sharply, with some solutions lingering the low across the
northern Gulf, and others more transient, shifting the low off to
the eastern Gulf by late Sunday. Additionally, Sunday afternoon in
the Bering has very little agreement with regards to timing,
features, and persistence. Generally, a trough will build over the
Bering into the early portion of next week, however at this time
little more details on impacts at the surface, and overall
timing/progression of this system are discernible.
-CL
&&
.AVIATION...
PANC...VFR conditions anticipated through the TAF period.
Turnagain Arm winds increase this afternoon and are expected to
bend into the airport. Sustained southeasterly winds around 15
knots with gusts as high as 22 knots should persist into the
evening hours and possibly through the early morning hours on
Friday before the pressure gradient across the region relaxes.
&&
$$
000
FXAK69 PAFG 160931
AFDAFG
Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
131 AM AKDT Thu May 16 2024
.SYNOPSIS...
Weather will be gradually quieting down across the state as
temps remain seasonal over the Interior and a strong storm out
west continues to weaken today. A fairly quiet breakup
continues, however ice remains thick along the Lower Yukon which
will continue to be monitored.
&&
.DISCUSSION...
Upper Levels and Analysis...
There is a large upper trough over Siberia and extending into the
West Coast with a 983 mb low moving up into the Chukchi Sea. Over
the Eastern Interior, there is a 550 dam upper level ridge in
place which is bringing the nice and quiet weather to the
Interior. South winds behind the departing arctic low will wane
today out west.
Model Discussion...
Models are in very good agreement with the upper air and surface
flow for the next few days. The Hi-res models were favored for
winds and a blend for precip, with consensus blend models for
RH/POPS. We will introduce an isolated thunderstorm threat for
Saturday for parts of the Interior.
Central and Eastern Interior...
Quiet weather today as a cool front shifts east to near Tanana
today, thus increasing cloud cover somewhat from yesterday.
Otherwise, winds are weakening across the Alaska Range with the
front shifting east today. Isolated showers in the afternoon will
be possible by Friday with more afternoon showers and a slight
chance for thunderstorms by Saturday, along with warming temps Fri
and Sat.
North Slope and Brooks Range...
South winds continue today but weaken as the low responsible
shifts north into the Chukchi. Temps will remain above seasonal
norms today with highs getting close to the record of 40 for
Utqiagvik. Winds turn back to east northeasterly Saturday with
temps falling back to normal, along with increased stratus and
possible fog chances.
West Coast and Western Interior...
The strong storm is weakening and shifting north today. A mix of
rain and snow showers continue through today and then taper off
tonight. A low will skirt the West Coast on Friday bringing rain
and snow showers mainly to Saint Lawrence Island. There will be a
scattering of rain showers across mainly the Interior as temps
slowly warm. Otherwise, the coast looks predominantly dry and
quiet Fri into the weekend.
Extended Forecast Days 4-7...
Some form of Interior ridging looks to be in place Sunday with
weak troughing over the West Coast. The GFS and ECMWF are much
more bullish on this scenario than the outlier Canadian, but
should this pattern develop it looks like it will warmup up next
week over the Interior with a couple shots for some 70 degree
readings. It looks wet and cooler out west as a storm possibly
moves in Tuesday.
Coastal Hazard Potential Days 3 and 4...None.
&&
.FIRE WEATHER...
Min RH values over the Interior tanked into the teens today. They
will remain in the upper teens to low 20s today over the E
Interior, but will rise over the Central Interior with more
clouds, cooler temps, and a shift in wind. With weakening AK Range
gradients fire weather conditions do not look like they will reach
critical values, but it will remain dry over the Interior today
with only some spotty Interior showers Fri, with a slight
chance/isolated thunderstorm chance Sunday for the E Interior.
&&
.HYDROLOGY...
Rivers north of the Yukon are starting to see some break up, but
with warming temperatures through this weekend that could start
to change by the weekend. The Yukon River upstream of Pilot
Station is partially open with mainly weak and rotting ice left
which lessens the chances of ice jams.
There was a report from Emmonak Tuesday evening stating that
river levels have been rising. There was still about 8 inches of
snow on top of the ice and people are still snow machining across
the river with about 3 feet of ice at Nunam Iqua last week. The
ice has not moved or broken in any way from Emmonak to Mountain
Village. Due to this strong ice in place, this will be an area of
ice jam concern in the future.
&&
.AFG WATCHES/WARNINGS/ADVISORIES...
AK...None.
PK...Small Craft Advisory for PKZ802>805-816-851-852.
Small Craft Advisory for PKZ806.
Brisk Wind Advisory for PKZ807-810-856.
Brisk Wind Advisory for PKZ808-809-855.
Gale Warning for PKZ811-857.
Brisk Wind Advisory for PKZ812-854.
Brisk Wind Advisory for PKZ813-850-853-859.
Small Craft Advisory for PKZ817.
Heavy Freezing Spray Warning for PKZ851.
Brisk Wind Advisory for PKZ858.
$$
Ahsenmacher
000
FXAK67 PAJK 152258
AFDAJK
Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
258 PM AKDT Wed May 15 2024
.SHORT TERM...First off, a little recap over the previous 18
hours. The consistent rainfall in the north was somewhat
surprising Tuesday night. Digging into it this morning, our
somewhat moist occluded front, orographic lift from southwest
flow, and some vorticity aloft helped keep sustained rain over the
Juneau area through the night. 12 and 24 hour amounts are still
below 1 inch, but a bit more than forecasted.
This afternoon these ingredients are becoming increasingly scarce
as the parent trough aloft begins its journey southeast, with the
low fully dissipating later this evening and widespread
precipitation tapering off. Upstream a surface ridge is building
into the Gulf, helping to establish northwest flow along our
coast and continuing to push moisture further south.
For Thursday morning a low marine layer is expected in portions of
the region, mainly along and south of Icy Strait. The main
forecast challenge today is the development of patchy fog but
confidence is low. As we move through the afternoon expecting a
nice day to develop, a moderate northwest breeze along our coast,
and sea breezes developing through the interior Panhandle. Another
weak system moves into the Gulf Friday, more details in the long
term.
.LONG TERM.../Friday into the weekend/...Unfortunately the
surface ridge that will be moving into the panhandle through the
day Thursday appears to be more transient in nature, as a weak
surface low is set to move into the northern gulf on Friday. Good
news is that with a lack of upper level support, this system is
expected to be dissipating as it progresses south and eastward.
This means still a low chance of light precipitation for the
panhandle, primarily expected for the southern outer coast.
However, this does mean even places that stay dry could still see
some more cloud cover. Overall still good for outdoor activities
as temperatures are expected to range from low to mid 50s in the
north to around 60 in the south to start the weekend. Also, with
the dissipating low and transient ridge, still not expecting
significant winds aside from a brief coastal jet heading into
Cross Sound on the north side of another ridge Saturday into
Sunday, though only expecting winds reaching around 20 kt with
higher gusts.
Another transient ridge will move in behind the decaying low Friday
into Saturday, with models beginning to diverge in their solutions
for the start of the week in terms of timing and strength of the
next system moving into the gulf Sunday. While onshore flow is
likely to continue throughout this period, low confidence in terms
of timing for any moderate precipitation returning to the panhandle.
Overall can expect a wet start to next week whether the rain arrives
Sunday night, or first half of the day Monday.
&&
.AVIATION.../ Through Thursday afternoon / Ceilings primarily
above 3500 feet across Southeast East Alaska Wednesday afternoon
and evening with a few locales between 2500 and 3000 feet.
Scattered to numerous showers however hardly impacting
visibilities. Am not anticipating large changes in the ceiling
heights, potentially some lowering overnight where 2000 to 3000
ceilings could be found. A second possibility is that with
moisture, some morning patchy fog developing which could impact
some locals to near 18z Thursday morning. The fog locales could
very well be diverse.
&&
.MARINE...
Gulf and coastal waters.
Changes: Increased winds west of Dall Island.
Buoys along our coast highlight a southwest swell 4 to 7 ft near
8 to 10 seconds and light winds. Expect this trend to continue
through tonight before a ridge moves into the Gulf Thursday
morning bringing northwest winds. For areas north of Cape
Edgecumbe, expecting a moderate-to-fresh breeze (15 to 21 knots)
but western Cross sound will see some slightly higher winds
develop. As we move towards Cape Ommaney south into Dixon, expect
a northwest strong breeze Thursday (22-27 knots). This will bring
fresh short period northwest seas riding over southwest swell,
but significant heights still remain under 8ft.
Inner Channels:
Changes: increased winds a bit Thursday evening near Pt.
Couverden and Lynn for southerly sea breeze.
Main threats over the next 36 hours continue to be some patchy
fog forming in portions of the Panhandle Thursday morning but
confidence is low in this threat. Expect any fog to burn off by
Thursday late morning and light winds in the central and north.
Moving into Thursday late afternoon expect a sea breeze to develop
but sustained winds continue to come in under 20 knots for most
areas. Be aware of some elevated winds near Pt. Couverden into
Lynn Canal developing in the late afternoon. Certainly a great day
to see if any halibut are out.
&&
.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ641-642-644-661-662.
&&
$$
SHORT TERM...AP
LONG TERM....STJ
AVIATION...Bezenek
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