661
FXAK67 PAJK 202257
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
257 PM AKDT Sat Jul 20 2024

.SHORT TERM...

A stacked low feature parked in the southern gulf will bring in
drier air from Canada, while kicking up some clouds for the
southern panhandle. Naturally, due to the clearing in the north
and in Canada, small and large scale sea breezes will take effect,
increasing winds in Icy Straight, Lynn Canal, and the upper
portion of Stephen`s Passage up to 20 knots. During the afternoon
period, there is the possibility of thunderstorms briefly passing
over the White Pass area as storm direction moves increasingly
eastward. Any thunderstorm development that does occur looks to
happen in the late afternoon.

.LONG TERM...
The long range forecast is broken up into two distinct period,
Monday, marked additional cloudiness working its way northward
with lighter winds, and Tuesday, with a potent easterly wave
bringing widespread showers.

Monday continues to be the calmer day, with increased cloudiness
and a modest increase in winds due to clearing skies and solar
radiation in British Columbia. The interesting situation is on
Tuesday, where a rather potent backdoor warm front from a low in
British Columbia moves over SE AK from the northeast. A somewhat
unusual situation where a major moisture source from continental
air is overrunning entrenched drier, cooler air to the south in SE
AK. This will lead to light to moderate rainfall for
approximately 24 hours. NE flow aloft moving over the Coast
Mountains could causing drying from downsloping winds. In
addition, dry air from the south will be drawn in via pressure
gradient flow at the surface. Therefore, actual rainfall is far
less confident than any one model would imply, being anywhere
between 0.50 - 2.00 inches. The EFI tables have tended to assert
caution, with a majority of the shift of tails over the eastern,
mountainous portion of SE AK and much less model consensus over
even the far inner channels. Similarly, NBM confidence remains
low, with the highest six hour period of rain being anywhere
between 0.25 - 0.75 inches of rainfall.

&&

.AVIATION...

MVFR to VFR flight conditions across the panhandle this afternoon
aside from some isolated IFR CIGs near Gustavus. General thinking
is low to mid-lvl clouds with predominate VFR to upper MVFR
conditions to prevail through tomorrow afternoon with CIGS AoB
5000 to 7000ft, outside of Haines and Skagway which should see
mostly SCT to FEW high level deck. Main aviation concern will be
potential of patchy fog development again tonight after 10z
through mid morning, dropping CIGS and VSBY into IFR to LIFR
flight categories. Anticipating CIGS to raise back up AoB 5000ft
by Sunday afternoon. Winds should remain around 10kts or less
through the TAF period.

&&

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

&&

$$

SHORT TERM...NC
LONG TERM....NC
AVIATION...NM

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