Graphical Hydro Meteorological Discussion

638
FXAK68 PAFC 020125
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
525 PM AKDT Tue Jul 1 2025

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: Today
through Friday afternoon)...

Southcentral Alaska remains in a col between upper level ridging
to the north and south, and upper level lows to the northwest and
southeast. The most notable features on satellite are the abundant
cumulus clouds developing across Mat-Su, the Anchorage Bowl, and
Copper River Basin in response to daytime heating. Meanwhile, a
front is draped across Kodiak Island, with higher clouds pushing
north across Kenai Peninsula. Generally, expect this pattern to
persist in the coming days, with cloudier and wetter conditions
over Kodiak Island/southern Kenai Peninsula, and warmer and more
convective conditions for the remainder of Southcentral Alaska.

Not much in the way of showers or thunderstorms are expected today
as the ridge to the north suppresses convection and relatively
fast mid-level flow shears apart cells before they can become
more organized. However, much more widespread showers and isolated
to scattered thunderstorms are forecast for tomorrow as a robust
upper level shortwave moves south to southwestward across the
Southcentral Mainland. Short-range, high resolution, convection
allowing models have come into much better agreement for tomorrow,
increasing forecast confidence. Generally, expect showers and
thunderstorms to begin firing off tomorrow afternoon along the
Alaska Range at first, then move across the Copper River Basin
into the Talkeetna Mountains, Wrangell Mountains, and perhaps as
far south as the Chugach Range. With decent mid-level flow, there
is a chance for these thunderstorms to make it across the
mountains and into parts of the Mat-Su Valleys. The primary
challenge will be determining how far these storms can drift
before daytime heating or even cooler air associated with high-
elevation snow (or the stable marine layer) causes them to weaken
and dissipate.

-KC

&&


.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (Days
1 through 3: Tonight through Thursday night)...

A mature low pressure system originating in the Bering Sea
continues to push onshore to Alaska`s west coast. Gusty southerly
winds and moderate to heavy rainfall has been persistent over the
last 24 hours from the Alaska Peninsula to Norton Sound as
abundant tropical moisture is drawn north across the region. Well
over an inch of rainfall has fallen in Dillingham, Bethel, and
many other locations under this large swath of moisture. A
shortwave trough diving south across the Central Aleutians today
will aid in pulling the parent low pressure system down across
Bristol Bay tonight and into the western Gulf by late tomorrow.
Continued southeasterly flow through this time period will allow
heavy rainfall to continue in the Bristol Bay region, particularly
upslope enhanced terrain along the Alaska Peninsula and the Wood-
Tikchik Mountains. Expect elevated water levels in rivers
surrounding the greater Bristol Bay area for the next several days
as recent rains work down the Wood-Tikchik lake system.
Precipitation will begin diminishing tomorrow afternoon as the low
moves south and downsloping from a shift to easterly flow begins
to dry out the area. High pressure over northern Alaska will aid
in a drying trend by Thursday, clearing skies and warming
temperatures in the Kuskokwim River Valley for the July 4th
holiday.

Farther west, a high pressure ridge is currently building in
behind the low and will work east across the Aleutian Chain. Areas
of fog are likely to redevelop for the Bering and Aleutians
beneath the ridge, before the front of a new low out of Kamchatka
sweeps across the western Bering Thursday morning. Guidance is not
yet in full agreement as to the exact strength and position of
this system, but another round of widespread rain and elevated
winds can be expected to move across the Bering through Thursday
night.


&&
.LONG TERM FORECAST (Days 4 through 7: Saturday through
Tuesday)...

The long term forecast starts with a large upper low in the
Alaska Peninsula region. This low will bring heavy rainfall for
the Alaska Peninsula and parts of Bristol Bay starting Friday and
continuing through the weekend. The low will also drive frontal
systems into the Gulf of Alaska on Saturday. This brings heavy
rainfall in Kodiak Island and the coastal regions of the mainland
through the weekend and into the workweek. Inland areas including
Anchorage will see less or no rainfall depending on downsloping.
The Copper River Basin and the Talkeetna Mountains could see
thunderstorms during the weekend due to higher instability and
easterly waves. There is high uncertainty with the forecast from
Monday onward with guidance showing many different scenarios.
Some guidance has multiple lows forming in the west and tracking
into the Gulf of Alaska, where others have the previous low
stalling out in the southern part of the Gulf. The only thing that
can be reasonably affirmed at this point is rainfall for Kodiak
Island and the Southcentral coastline. As for Southwest Alaska
for next week, again, uncertainty rules the day. However, some
kind of col or weak flow may set up and lead to drier conditions
in the mainland. The Bering will see some kind of low move through
with rain chances and gusty winds possible.

-JAR

&&.AVIATION...

PANC...Southeasterly flow is now entrenched aloft, which means
cigs should remain VFR through the TAF period. Turnagain winds
have already developed and will continue through early Wednesday
morning and will return Wednesday afternoon.

&&


$$

819
FXAK69 PAFG 012211
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
211 PM AKDT Tue Jul 1 2025

.SYNOPSIS...
The northeast flow around the high pressure will increase on
Wednesday. Windy conditions will develop Wednesday over the
higher terrain of the central and eastern Interior increasing
the fire danger. A disturbance will spread some showers and
isolated thunderstorms over the eastern Interior and eastern
Alaska Range near the Canadian border early Wednesday. In
western Alaska rain along the coast from Bristol Bay to the
Seward Peninsula will diminish tonight.

&&

.KEY WEATHER MESSAGES...
Central and Eastern Interior...
- The Fortymile Country...Upper Tanana Valley and Eastern Alaska
Range will have isolated showers and thunderstorms today and
Wednesday.

- Temperatures in the upper 70s today in most Interior valleys
warm into lower 80s on Wednesday.

- Hot...dry and windy conditions will develop Wednesday in the
higher terrain of the Central and Eastern interior increasing
wildfire concerns.

West Coast and Western Interior...
- Rain along the West Coast and far Western Interior from the
Seward Peninsula south to Bristol Bay. These rains will
gradually diminish on Wednesday.

- Southeasterly winds over western Alaska remain strong into
tonight before diminishing Wednesday. Sustained values of 20 to
30 mph expected for most areas in Bering Sea through the Bering
Strait. Southeast winds 15 to 25 mph develop late tonight
through the Norton and Kotzebue Sounds.

North Slope and Brooks Range..
- Warmer and drier conditions over the next several days.

- Strong east winds with low stratus and fog at night will
continue along the Arctic Coast.

- Isolated showers today over the far western Brooks Range.

&&

.FORECAST ANALYSIS AND DISCUSSION...
High pressure centered over the central Arctic Coast will
continue to dominate the weather pattern for the Interior through
the weekend. Warmer and drier conditions will continue into the
weekend. Northeast winds will increase enough on Wednesday to
warrant the Red Flag Warning for mainly the higher terrain of the
central and eastern Interior. Coordination took place with AICC
and our IMETs. Those winds decrease on Thursday but the low level
instability will still support convective plume development over
the fires. In western Alaska rain along the coast from Bristol
Bay to the Seward Peninsula will diminish by tonight and Wednesday
as the Bering Sea low weakens and moves south. We definitely have
low level haze from wildfire smoke south of Fairbanks toward the
Alaska Range. The WRF pushes the smoke west as the northeast flow
increases Wednesday. That might help keep the wildfire smoke from
deteriorating conditions until this weekend. In the extended the
High Pressure ridge remains centered over the Arctic Coast.
Shortwaves will undercut the ridge in the easterly flow and should
increase thunderstorm coverage. Timing of those shortwaves is
uncertain right now. Best take attm is isolated showers and storms
over the Alaska Range westward to the Nulato Hills Friday and
Saturday.


&&

.FIRE WEATHER...
Critical fire weather continues to develop over the next 24 hours
as much drier air as pushed into the region from the
Arctic/Yukon. Winds still look gusty out of the east-northeast;
by-and-large most of the interior should see 15 to 20 mph gusts by
Wednesday afternoon. For folks on fires in more complex terrain,
keep a watchful eye on channels/gaps/valleys exposed to the
northeast and also along ridgetops, where locally higher winds of
30mph is possible. Confidence is high for temperatures to reach
into the low to mid 80s over the next few days, with minimum RH
hitting the low 20s to upper teens. Given the dry air, recovery of
RH in the morning is generally expected to worsen, perhaps
reaching as high as 60%.

Thunderstorms will impact the eastern Tanana Valley late this
afternoon and Wednesday, with the potential for these storms to
penetrate further into the interior. Keep a watchful eye on any
developing thunderstorms as steering winds will push them to the
west. Erratic and gusty outflow winds could reach 30 to 40 mph.

&&

.HYDROLOGY...
No concerns along the rivers. No impacts are expected from the rain
in the west or along the eastern Alaska Range the next couple days.

&&

.EXTENDED FORECAST DAYS 4-7...
Coastal Hazard Potential Days 3 and 4...None

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Red Flag Warning for AKZ931>935-938>947-949.
PK...Small Craft Advisory for PKZ804.
Small Craft Advisory for PKZ805.
Small Craft Advisory for PKZ807-856.
Small Craft Advisory for PKZ808-809-855.
Brisk Wind Advisory for PKZ813-859.
Small Craft Advisory for PKZ852.
Small Craft Advisory for PKZ858.
&&

$$

Maier/Park

376
FXAK67 PAJK 012347
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
347 PM AKDT Tue Jul 1 2025

.SHORT TERM...
A vertically stacked low will continue to stagnate and spin over
the central panhandle Tuesday, gradually weakening and sliding
southeast through the day Wednesday. As a result, light and
occasionally moderate rain showers will continue to impact the
panhandle Tuesday afternoon through Wednesday. As of this
discussion showers are primarily peppering the central panhandle.
Convection will slacken overnight before building once more
Wednesday with daytime heating. Heavier showers capable of rapid
drops in visibility and erratic winds remain possible in early
evening Tuesday and could form Wednesday afternoon as well.

For the southern panhandle, a break from showers is expected to
continue through Tuesday evening, before the weakening low slides
southeastward bringing showers back late Tuesday and through the
day Wednesday. Similar to Tuesday, some showers that develop could
be heavier due to orographic enhancement, but most are expected
to be light. Cloud cover and showers has limited temperatures to
upper 50s and low 60s Tuesday, with some chance for more warming
Wednesday, but even better chances heading towards the weekend.
For more information on the holiday weekend coming up, see the
long term discussion.

.LONG TERM...Thursday through Sunday...
We are looking for a pattern shift starting late Wednesday as
broad low pressure over the eastern GULFAK weakens and weak
ridging starts to setup over SEAK. While a drier trend to the
forecast late Wednesday into the weekend is expected, we won`t be
rain free. The weak nature of the ridge with periods of weak upper
energy ejecting out of the central GULF of AK upper level low
means that scattered afternoon showers remain possible Thursday
and through the 4th of July weekend. It should not be a washout
and guidance does not have any heavy precipitation through
Saturday. Ensemble and deterministic guidance remain at odds as to
if showers will survive pushing down from the interior and Yukon
into the far northern panhandle over the weekend, while there is
higher confidence that a trough rotating around a low in the
western gulf will approach the panhandle sometime Sunday. /Garmon

&&

.AVIATION...
For the 00z TAF update, no major changes to current forecast
thinking. We continue the trend with most of the rain gradually
tapering off for the northern panhandle through the evening, but
we will keep rain going for the central and southern areas toward
Wednesday morning. Ceilings are going to bounce between IFR and
MVFR with passing rain activity, but trending toward a period of
MVFR or low-end VFR toward early evening before low ceilings of
IFR to LIFR move back in tonight with patchy fog likely. No wind
shear areas to note into tonight as the weak low continues to
diminish over the central Panhandle today...however a bit of a
seabreeze expected for Taiya Inlet and the Skagway Airport to
continue into early evening with SW winds 15-25 kts.

&&

.MARINE...
Outside: A ridge of high pressure is building over the eastern
gulf Tuesday. This is causing W-NW winds along the outer coastal
waters of about 10kt with combined seas of 4ft or less. Buoys are
showing a S-SW swell with a 14 second period. This pattern
persists over the coming days while the ridge axis shifts east
along the coast and becomes broader with little pressure gradient
going into Friday. Lower pressure starts to encroach the central
gulf from the west Friday into Saturday causing winds to turn out
of the SE and start trending up 10-20kt.

Inside: A trough of low pressure lies over the central inner
channels, Northern Chatham area as of this afternoon. This is
causing some varied wind directions and some showers that have
occasional gusts of 15-20kt (Scull Island), but then sustained
winds drop back to about 10kt. Sunshine to the north is causing a
sea breeze with winds of 15-20kt in Taiya Inlet near Skagway.
Otherwise most winds are 5-15kt. After evening sea breezes, winds
will trend down overnight and be fairly light and variable by
Wednesday morning. Expect W-SW sea breezes to pick up across the
north again in the afternoon to around 15kt. This pattern of light
morning winds and afternoon increases continues through the week.
Trouble spots will likely be: Taiya Inlet, Cross Sound, Rocky
Island, and Young Bay.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...None.

&&

$$

SHORT TERM...STJ
LONG TERM....JG/STJ
AVIATION...JG
MARINE...Ferrin

Visit us at http://www.weather.gov/Juneau