Petersburg, Alaska 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

243
FXAK67 PAJK 200549
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
949 PM AKDT Thu Jun 19 2025

.UPDATE...Updated aviation section after 06z TAF issuance.

&&

SHORT TERM...Showers have continued to stream westward across the
panhandle from British Columbia as a broad upper level circulation
pulls moisture and developing afternoon convection over the area.
In the far northern panhandle, Convection developing over
southern Yukon Territory continues to slowly drift towards the
border, with none quite making it as of this discussion. Isolated
thunderstorms remain possible through the afternoon and early
evening this Thursday for the far northern panhandle, as well as
the eastern central inner channels. However, most of these storms
are expected to dissipate or weaken significantly before reaching
the inner channels after passing over the Coast Mountains and ice
fields.

An early morning stratus deck that developed over Lynn Canal and
the Chilkat Valley served to delay daytime heating for Haines and
Skagway Thursday. This also lead to a delayed onset of sea
breezes in those areas, as well as lessening their strength by this
afternoon, compared to Wednesday.

High pressure building over the interior and a ridge building over
the central gulf will be the primary influences heading into the
weekend, as the broad low over the southern gulf finally vacates
the area. Skies will begin to clear from north to south overnight
Thursday and into Friday. Aside from localized sea breezes Friday
afternoon, winds in the inner channels are expected to be largely
light and variable as the gradient overall slackens overnight into
Friday. With the clearing skies, temperatures in the far northern
panhandle are expected to reach the mid to upper 70s, with highest
temperatures expected a bit inland in areas not influence by sea
breeze effects. A heat advisory has been issued for the upper
elevations of the Haines Highway including Klukwan, lasting
through Saturday. Highest temperatures expected in the late
afternoon through early evening hours each day. For more
information on this warm and dry pattern, see the long term
discussion.

LONG TERM...A ridge of high pressure is building over the interior
and is sliding towards the panhandle. This ridge will bring dry and
warmer-than-normal weather to the area.

Key messages:
-Sunny and dry through the weekend.
-Afternoon temps will warm to upper 60s to 70s for most of the area.
Isolated pockets of near 80 degrees are likely.
-A potential marine layer may keep temps along the coast a little
cooler.
-Ridge breaks down early next week, ushering in low chances for rain
beginning on Tuesday.
-Wind speeds in marine areas will increase for the afternoon hours
as sea breezes kick in. Speeds will decrease in the evenings.

Details:

Upcoming ridge of high pressure will bring dry weather, clearer
skies, and some warmer-than-normal temperatures. Models showing
850mb temperatures between 10 and 15 degrees C moving into the area.
850mb temps like this means surface high temps in the 70s are
usually a pretty good bet.

That being said, there is evidence of a marine layer that could form
along the coast. This could give areas along the coast overcast
skies and lowered high temps in the 50s to low 60s. Due to the
nature of marine layers, confidence is low on where the marine layer
sets up but it will be worth monitoring through the weekend.

The ridge breaks down early next week, allowing a trough to slide
into the Gulf of Alaska, bringing back the chances for rain
beginning on Tuesday.

Winds look to stay on the lighter side over the region through the
weekend. Exceptions include Lynn Canal and Stephens Passage where
the sea breeze may set up, increasing winds to around 15 to 20 kts
for the afternoon before calming back down in the evening.

The other exception will be along the southern outer coast and
coming out of Chatham Strait and Clarence Strait, where northerly to
northwesterly winds upwards of 15 to 25 kt are looking likely. These
winds are not expected to last long, as they look to calm back down
Sunday afternoon due

&&

AVIATION... Largely VFR conditions expected with some drops to
MVFR for parts of the central and southern panhandle tonight as
showers from the east continue to move through the region.
Expecting ceilings to drop to between 1500 and 3000 ft as these
showers move through, mainly impacting the Icy Strait corridor
area down through Petersburg and Wrangell. Petersburg may see some
drops to IFR late tonight as cloud ceilings may drop to below
1000 ft and some mist potential around 10Z that may also drop VIS
to 4SM. The rest of the southern panhandle and along the outer
coastline near Sitka will instead see more VFR conditions lasting
into the morning as skies begin to clear, as showers are not
expected to push through these areas tonight. The northeast Gulf
coast and Lynn Canal area will see generally clearer skies with
the exception of some potential convective clouds pushing in from
the NE through the night, alongside some potential for haze at
higher levels. Other than ceiling and visibility drops due to
showers, no aviation hazards are anticipated.

&&

MARINE...
Outside: Westerly winds increasing to moderate to fresh breezes
(11 to 21 kts) with the ridge approaching in the gulf. Dixon
entrance will continue to see easterly winds as the persisting low
in the southern gulf continues to spin up bands of clouds and
precipitation for the panhandle through Thursday evening. Wave
heights remain around 4 to 5 ft as a SW swell diminishes through
Thursday evening.

Inside: Onshore flow will increase as a ridge approaches in the
gulf through the day. Upper level easterly flow keeps bands of
clouds and scattered showers in the forecast for the central and
southern panhandle through Thursday afternoon, with some isolated
thunderstorms possible for Lynn Canal and Stephens Passage. Aside
from afternoon sea breezes in the northern panhandle, overall
winds will remain light. More extensive cloud cover over the
central panhandle will likely limit any brief thermal gradient
winds picking up along Chatham and Stephens Passage this afternoon
and evening. Winds to remain light Friday and heading into the
weekend.

&&

HYDROLOGY...An increase diurnal heating over the panhandle with
an increase in freezing level to above 8000 ft over the northern
panhandle increases the snowmelt in the streams. Chilkat River
has been responding well to the increased flow and looks to be
crossing over Minor Flood levels Friday and Saturday. So we when
and added an advisory for the Chilkat River into the weekend.
Other streams and rivers likely rise from the increased snowmelt
too.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Heat Advisory until 7 PM AKDT Saturday for AKZ319.
MARINE...None.

&&

$$

SHORT TERM...STJ
LONG TERM....GJS
AVIATION...Contino
MARINE...STJ
HYDROLOGY...Bezenek

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