Southeast Alaska forecast discussion
National Weather Service Juneau Alaska
306 PM akdt Monday may 20 2013
Short term...high pressure over the Gulf and interior/Yukon
territory to persist with an inverted trough of low press from
Vancouver Island across the southern half of the Panhandle.
Overall mostly clear skies across the region...with the exception
of mostly cloudy skies over the southern third. Clouds wrapping
into the trough from British Columbia keep replenishing any of
the clouds moving out of the area. Clouds spreading of northern
British Columbia are dissipating across the north central
Panhandle.
After a day of drying and starting with less cloud cover
temperatures across the north central Panhandle and northeast
Gulf Coast will have better cooling tonight so continued the
trend of cooler temperatures tonight. Have upgrade the freeze
watch to a warning... and then will adding an advisory for the
Haines and Skagway regions for late tonight.
Models suggesting a small cross barrier wind event in the Juneau
area towards morning so will be mentioning some higher gusts. A
tighter gradient over the Lynn Canal region has prompted ME to go
with a gale for northern Lynn and adding a small craft for
southern Lynn too. Other more Standard marine zones of the Inner
Channels will also have the small craft. For the outer waters the
25 to 30 knots there are more for further offshore than near shore I
think. The initial wave initialization I used looked high for the
outside waters so I tempered the wave heights a shade as none of
the buoys out there were reporting lower than initial thinking.
Tuesday looks to stay about he same cloud cover wise and even
slightly warmer. May need watch for afternoon sea breezes in the
typical locales as well. Potential for patchy fog near morning
but not expecting wide spread problems.
&&
.Long term...Rather quiet long term forecast as we have a
persistent ridge over the Gulf, both at the surface and aloft,
and an inverted trough over the Panhandle. Both of these features
are promoting northwest flow across the Gulf and offshore flow over the
Panhandle which is helping to keep US mostly clear and dry. These
conditions are expected to last through the week and into the
weekend with temperatures getting warmer through middle week as a
lingering cold upper trough moves through. Overnight lows will
still dip into the low to middle 30s in the northern Panhandle on
Wednesday morning so some frost advisories may still be needed then,
but after that the upper trough will have moved on and overnight
lows will rise. Day time highs will get into the 60s in most
areas through the weekend.
Some things that could throw a wrench into this is the return of
the marine layer on Thursday and Friday and an upper level low over the
Yukon at the same time. Low level flow over the Gulf starts to
turn more to the west rather then the northwest on Thursday as the ridge
flattens. This results in marine layer clouds starting to
approach the outer coast especially Thursday and Friday night. Areas that
do see the marine clouds will see higher low temperatures than
stations farther inland and, if the clouds do not burn off very
quickly, lower high temperatures Friday and Sat.
The upper low over the Yukon brings the possibility of some
showers showing up along the Coast Mountains late week. Current
thinking is that most of them will stay on the Canadian side of
the mountains or at least to the higher elevations, but some
spill over clouds could still flow over the Panhandle.
Long range models are in decent agreement through the period
with some small differences in details here and there. Decided on
using the NAM and European model (ecmwf) for Middle Range updates and wpc for later
periods.
Ajk watches/warnings/advisories...
public...freeze warning from 11 PM this evening to 7 am akdt Tuesday for
akz017-020-021-025.
Frost advisory from 1 am to 7 am akdt Tuesday for akz018-019.
Marine...Gale Warning for pkz012.
Small Craft Advisory for pkz011-013-021-022-031>034-036-041>043-
051.
&&
$$
Bezenek/eal
