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000
FXAK67 PAJK 201345
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
545 AM AKDT Sat Apr 20 2024

.SHORT TERM.../Through Tonight/...Southeast Alaska remains under
the influence a ridge of high pressure today that has been
dominating our weather over the last several days. As it continues
to move eastward away from the area, it will gradually loosen its
fair weather grip over the area through the period. The vast
majority of Panhandle areas will remain under partly cloudy to
clear skies and have dry conditions through the period. Due to
that, we expect high temperatures to warm nicely this afternoon,
potentially breaking records, once again. A decaying front and a
weak area of low pressure / a wave riding northward up it will
approach and begin moving into the southern Panhandle toward the
end of the short term forecast period, which will bring increasing
clouds starting late this afternoon through tonight for the
southern Panhandle and chances for light rain toward the late
tonight / early tomorrow morning timeframe. Winds will remain on
the lighter side with some sea breezes and land breezes through
the period as the pressure gradient continues to relax over the
eastern Gulf / Southeast Alaska region, all areas will receive
widespread solar radiation during the day today, and most areas in
the central and northern Panhandle will have clear to partly
cloudy skies tonight for adequate radiational cooling.

Forecast confidence is above average through the period as
deterministic models are in good agreement and ensemble member
spread is narrow.

.LONG TERM...A shift in the pattern is underway in the long range
forecast, as more active weather returns to the panhandle Monday
and potentially through the first half of the week - though
active in this case means occasional chances of rain, rather than
any strong organized systems.

Aloft the ridge which has been over the panhandle is slowly being
shifted towards a more W/E axis as opposed to its previous N/S axis
as an impulse of energy begins building a trough along a similar W/E
axis to its south. Ultimately, this trough will succeed in advancing
N, successfully displacing the ridge on Sunday. This will bring with
it a weak occluding frontal band, and some chances of showers
across the area. The dynamics with the system don`t look all that
impressive, given a distinct lack of upper or mid level support,
and a lack of any significant amount of moisture. The possibility
of cyclonic vorticity advection along the trough axis contributing
to some enhanced precipitation (and possibly even an embedded
wave within the front), which could move into the southern
panhandle is a possibility. At this time though, that is far from
set in stone, as the trough - if it builds slightly more than
anticipated, could just as easily develop a wave which impacts
Canada more than it does SE AK.

Afterwards, rapidly growing disagreement in the operational
guidance, driven by the collapse of the organized steering flow
aloft over SE AK, necessitates a turn towards reliance on ensembles.
A low over the Central Gulf - associated with the advancing trough,
may attempt to veer inland towards SE AK. Should this happen,
anticipate precipitation to overspread the panhandle. Conversely, if
the low veers off in a different direction, SE AK could remain dry
for Monday, aside from a few showers, and potentially through the
remainder of the week. For the time being, chose to keep some
chances of showers in the forecast on Monday - but the potential
does exist for skies to be clearer than currently anticipated,
should the relevant low not move into the area, and offshore flow
take over. Confidence is starting to grow that Tuesday onwards,
may favor drier weather - along with corresponding clearer skies,
and greater diurnal shifts.

Made some changes to the sky and PoP grids to reflect the greater
potential for drier weather Tuesday onwards, along with some minor
changes to temperatures to increase the diurnal range.
Additionally did some work to reflect changes in winds based on
the drier weather.

&&

.AVIATION.../Until 12Z Sunday/...VFR conditions reign supreme over
SE Alaska once more through Saturday under the continuing
presence of high pressure. Late Saturday night and Sunday morning
will see some high cloud cover pushing into the southern panhandle
with showers possible. Still no significant wind concerns, though
localized stout afternoon sea breezes remain likely.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ651-652-661>664-671-672.

&&

$$

SHORT TERM...JLC
LONG TERM....GFS
AVIATION...STJ

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