FXAK67 PAJK 242257
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
257 PM AKDT Sat Jul 24 2021

.SHORT TERM.../Saturday evening through Monday as of 3pm
Saturday/...The low-pressure system in the Gulf is slowly moving
southeast and weakening through the weekend. A few resulting
shortwaves of precipitation will continue to move into the
panhandle as a result of onshore flow. Cloud clover will remain
above 50%, but the central/northern panhandle including Juneau 
and Gustavus are forecasted to have mostly dry conditions Sunday 
and Monday.

Slight chance of precipitation late Sunday evening in Skagway and
Haines as a convective band of precipitation moves west,
eventually reaching Yakutat bringing a chance of precipitation.
The probability of precipitation will increase through the day
Monday from south to north. Expect the heaviest amounts of
rainfall at higher elevations.

Winds will have a diurnal trend in the short term, with winds
decreasing to light and variable overnight and increasing to
southerly 10 kts during the day as the sea breeze kicks in.
Temperatures remain slightly below normal as the clouds will
remain, resulting in highs in the upper 50s and low 60s.

.LONG TERM.../Monday through Saturday as of 10 PM Friday/... 
The long term period features a weakening low in the SE Gulf 
which will dissipate by midweek. High pressure then builds over 
NW canada and Southern Alaska by Wednesday and remains in the 
area through the weekend. Ensembles are all in general agreement 
with this pattern; however deterministic models diverge on the 
details of the evolution of the ridging. Due to model run to run
inconsistencies the forecast was nudged heavily to WPC beyond 
Wednesday, which favors a blend of the EC and GFS Ensembles. 
Current forecast is for an SE-NW oriented elongated area of high 
pressure to remain over the Panhandle through next weekend. 

As far as sensible weather, confidence is increasing in a drier 
weather pattern developing through the end of next week despite 
lower confidence regarding the placement of the high. Before the
drier weather comes, Monday features showers increasing from south
to north as a wave pushes into the Panhandle. Heaviest and most 
widespread shower activity is expected to remain across the 
Southern two thirds of the panhandle with more isolated showers 
making their way further north. Expect the driest portion of the 
Panhandle this week to be Upper Lynn Canal as the mountains tend 
to wring out much of the moisture in a southeasterly flow pattern.
The latter half of the week should feature another drying trend 
as flow becomes easterly and higher pressure builds into the 
region. Due to model uncertainties regarding the exact location
and shape of the building ridge, kept a slight chance of showers
in the forecast along the Coast Mountains and typical upslope
areas through the end of the week. However, the trend over the 
past few days has been to slowly decrease PoPs for the end of the 
week.

Winds through the period remain relatively light, especially
through the Inner Channels. Winds 15 kt or less expected through 
next week. If more sunshine and surface heating occur in between 
showers, then stronger afternoon sea breezes may occur in Icy 
Strait and Lynn Canal. An increase in Southerly winds in Northern
Lynn Canal and Taiya Inlet is also possible next week as surface 
ridging builds over the Panhandle; however confidence is still 
low regarding the exact pressure gradient pattern associated with 
the ridge.

Expect a slight warming trend in temperatures through the week.
Coolest days will be Monday and Tuesday, especially across the
south with increased clouds and showers. With 850mb temps steady 
around +3 to +5C, expect highs generally in the upper 50s to 
lower 60s Monday and Tuesday. By the end of the week, more 
sunshine plus slightly warmer 850mb temps should lead to highs in 
the mid 60s to near 70 for most areas. 

Blended heavily to WPC through the long term period due to
run to run inconsistencies in the deterministic models. 

&&

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

&&

$$

KRT/CM

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