Scientific Forecaster Discussion
Southeast Alaska forecast discussion
National Weather Service Juneau Alaska
348 PM akst Thursday Nov 26 2015
Short term...still at tale of two features for Southeast Alaska.
The first is the ridge of high pressure over Southeast Alaska that
is holding the precipitation away from the Panhandle. This ridge
is slowly continues to be forced east into British Columbia. A
strong flow pattern along a slow moving frontal band has heavy
rain falling in the Yakutat area. Gusty winds along the front of
15 to 25 knots and gusts up 35. The front will slow to stall and rain
will continue into Friday. Do expect the precipitation to diminish
slightly early in the morning which will increase in the afternoon
as the next wave and impulse.
Rain will start to spread into the northwest part of the Panhandle
for Chichagof Island and Glacier Bay as the front drifts slightly
more east. As the front moves closer winds in the Inner Channels
will increase due to the pressure gradient tightening up. Used NAM
as a basis for forecast adjustments today. Confidence is average.
Long term...still some model differences on where axis of
heaviest precipitation will occur over the weekend...and this is mainly
due to potential low pressure waves forming on the front over the
far eastern Gulf. Ended up using a blend of the 12z European model (ecmwf) and NAM to
handle this system through daytime sun. Heavy rain over the NE Gulf
Coast should shift into the northern Panhandle Friday night...then the
Central Area Sat. May get as far S as the southern outer coast Sat.
Looks like a wave may try to shift the heavier precipitation band a bit
to the north Sat night and sun. Still looks like a general 2 to 5 inch
rain with isolated 8+ inch totals where heavy rain persists
longest through sun. The snow level looks like it will be high
enough only for White Pass to have chance for any significant
snowfall...and only at the very top of the pass it appears. Think
if they get heavy snow it will be Sat-sun...but confidence is low
in whether the snow level stays low enough for all snow in the
pass...so will not issue any winter weather hazards at this time.
There will be gale force winds ahead of the front through Friday
night...then potentially more gale force winds Sat ant Sat night
over the southeast Gulf as low pressure wave moves northward. Most Inner
Channels will peak at Small Craft Advisory levels although near Cape Decision some
gales may occur Friday night and Sat night. Clarence Strait and southeast
part of Frederick Sound may also see gales Friday night through sun.
Temperatures will be mild through the weekend with lows generally in the
upper 30s to lower 40s and highs in the 40s over much of the
area near sea level.
Next week...models still struggling with where front will go and
timing of another system or two coming toward the area. Decided to
keep area generally wet and mild for Monday-Thursday based on long wave
public...strong wind from 3 am akst Friday through Friday afternoon for
Strong wind until 6 PM akst this evening for akz018.
Marine...Gale Warning for pkz034-036-041>043-051-052.
Small Craft Advisory for pkz011>013-021-022-031>033-035-053.
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