Small Craft Advisory 190, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
534 AM AKDT Sat Mar 25 2017

.SHORT TERM...Surface analysis and satellite imagery indicate a
weakening low over Prince of Wales island moving north, with
precip expanding northward as well. Ptype is mostly liquid over
southern areas and the outer coast with mixed precip over the
central panhandle transitioning to snow further N. Accumulating
snow will persist through the morning over the N/Ctl inner
channels. Highest accumulations still expected in the Juneau area
where up to 3 inches possible through mid-late morning. Precip
will then transition to showers and ptype will become mixed then
liquid. As the low moves inland this afternoon, sct showers will
gradually diminish this evening. Focus then turns to the next,
near gale, low moving N approaching the SE gulf overnight.

Nly winds over the N channels will ease this morning, turn
southerly this afternoon in response to the low moving inland
before swinging back to Nly and increasing as the next low begins
to impact the region. Advisory level winds will develop over the
outer coast late this evening. Also expect SEly SCA winds over
Clarence Strait late tonight along with N Lynn and Cross Sound in
response to the approaching low.

Precip chances will increase over the southern panhandle overnight
and given the timing expect ptype to mixed or snow but little to
no accumulation expected overnight.

Current forecast represented this reasoning well and used hi res
guidance concentrating on local effects. Biggest challenge is
timing of the wind shift over N panhandle. Forecast confidence
remains above average.

.LONG TERM...Starting Sun the effects of the next weather system
spreads into southern SEAK with increasing SE winds and
increasing likelihood of pcpn. Expect a 994 mb surface low to move
NE just off the coast through Mon and be west of Yakutat Mon
night. The zone where precip could be mixed rain and snow lifts
northward from the central panhandle Sat to Icy Strait corridor
Sun. This shortwave should be fairly strong with widespread precip
and gale force gusts offshore through Mon night.

A wavy southwest flow aloft affects SEAK Tue and Wed. This will
keep the chances of precip fairly high but not excessive total
precip amounts. Temps expected to nudge close to normal for late
March with daytime highs in the 40s next week and snow levels
rising. The westerly jetstream core of greater than 100 kts has
been located around 40N and aimed at PacNW but is forecast to
gradually tilt northward next week due to upper level ridging
along the CONUS west coast. Temporary ridging may build as far
north as SEAK by Thur or Fri next week and result in a break in
the precip and feel noticeably spring like at least in Ketchikan
and the adjacent southern panhandle.

Forecaster confidence fairly high regarding the general moist
pattern through mid week then drying. Made little or no change to
existing grid forecast.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ012-022-036-041>043.
&&

BC/TA

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