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fxak67 pajk 221414 
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Southeast Alaska forecast discussion
National Weather Service Juneau Alaska
614 am akdt sun Oct 22 2017

Short term.../through Monday night/ a low pressure area just
offshore the central outer coast will move across the central
Panhandle today and weaken. Another low will move NE into the area
Mon, but there are some differences in model low tracks. They are
generally showing a track across the central Panhandle, but there
are about 100-150 mile differences in where it crosses the Central
Area. Current forecast has it on the more northern end of the
model tracks, and given some uncertainty on another system to the
west which could affect the low track, decided to keep that system
track as is. Did adjust the low crossing area today by using 06z
namnest, which shifted it a bit further north.

Low moving through the area today will have a small band of 30-35
kt winds on the S and east side of it. This wind band should affect
mainly the central Panhandle. Winds of 20-30 kt will be possible
further S, with 15-20 kt for much of the north today, although these
winds will be diminishing. Enhanced shower activity will occur on
east side of the system, with the heaviest showers expected over the
Central Area.

Low moving in for Mon will have more widespread wind and some
heavy rain with it. Low level jet at 925 mb could be 60+ kt ahead
of associated frontal band, but will be within warm advection, so
downward momentum transport is not expected, but strength of
system overall should be enough for locally strong winds over the
southern area. Rainfall could exceed 3 inches over the southern
area Mon into Mon evening. Put out Special Weather Statement about this system for
southern area. Further N, could see significant rainfall as well
in deformation/frontogenesis band on north side of low, and another
complication to worry about is potential for snowmelt cooling to
occur, which could cause precip to change to wet snow in most
intense precip. Models hint at this possibility with small area of
near zero 925 mb temps in north-Central Area. Given some low track
uncertainties, not mentioning this snow potential in forecast attm
but later shifts will need to monitor.

Long term.../Tuesday through Sunday/...as the surface low that
is expected to impact our area Monday exits east into Canada, an
additional two surface lows are expected to develop, one over the
northern Gulf and a second out of the south-central Gulf. The low
to the north should quickly weaken and lift northeast into the
Yukon territories of Canada. The second low with a more southern
origin is expected to push east-northeast through the southern
portion of the Panhandle and continue into British Columbia,
Canada. This system will also bring a more subtropical push of
moisture on tuesday; precipitable water analysis shows some
anomalously high values with this system, so we're expecting a wet
event centered near the southern Panhandle, as of right now. As
both of these features weaken, a ridge of high pressure will begin
to build over the eastern Gulf Wednesday, with the ridge axis
stretching north to south just offshore of the Panhandle. The
offshore flow with this ridge should provide a brief respite from
the precipitation that has been constant these last few days.
Winds are also expected to diminish across the Panhandle briefly
with this ridge.

All models continue to point to a very wet event Thursday into
Friday of next week. The remnants of typhoon lan are expected to
wrap into a trough coming across the Bering Sea early this week,
with the moisture becoming embedded with the circulation.
Precipitable water analysis also indicates some anomalously high
amounts with this system. However, models still cannot agree as to
where the more significant precipitation amounts will fall in our
area.

Generally, there has not been a lot of model agreement as of late,
especially regarding the set up of surface level features. We
decided to lean more towards the European model (ecmwf) for the earlier long term,
mainly Tuesday through Thursday, as it has had more run to run
consistency and has performed better than other models with
current systems.

&&

Ajk watches/warnings/advisories...
public...none.
Marine...Gale Warning for pkz042.
Small Craft Advisory for pkz012-013-022-031-033>035-041-043.
Small Craft Advisory due to seas for pkz051-052.

&&

$$

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