Scientific Forecaster Discussion
Southeast Alaska forecast discussion
National Weather Service Juneau Alaska
530 am akdt Sat Mar 15 2014
Short term...active weather pattern continues through the short
term forecast period. A gale force low will move into eastern
Gulf and then make landfall over southern Panhandle early Sunday
This morning, winds across the area were generally from the
south. However, this would not last long. As the gale force low
approaches the Panhandle, southerly pressure gradient will become
parallel later this morning, and then will become northerly by
the afternoon. By late tonight, this low will make landfall in
southern Prince of Wales Island. Northwesterly gale force winds
will be found across the eastern Gulf of Alaska.
Categorical precipitation will be over the southern Panhandle.
Precipitation potential will lower further north. Mostly dry
conditions should be found across Yakutat and northern Panhandle.
For Saturday night, temperatures will be cold enough for snow to
occur over central Panhandle, with minor snow accumulation taking
place in the area.
Forecast confidence is about average. There are still
uncertainties on the exact timing of the wind shifts from south
to north. Utilized European model (ecmwf) and NAM as the models of choice. European model (ecmwf)
initialized the gale force low very well, while NAM has a good
handle on the future position of this low pressure system.
Long term...progressive pattern aloft is allowing a series of
upper troughs and ridges to move across the map from west to east
with upper flow varying from zonal to highly meridional. Features
aloft are strong enough to have well developed surface
reflections in the form of lows and their associated fronts,
followed by surface highs/ridges.
As precipitation from one front departs to the east at the
beginning of the extended range forecast period, the next front
will be crossing the western Gulf. This next front will be over
the Panhandle by Monday afternoon. A devloping wave along the cold
frontal boundary will reinforce precipitation over the central and
southern zones on Tuesday. Not calling for heavy precipitation at this
time, but will be watching closely. After a brief period of
somewhat drier weather, the next front will approach from the west
with precipitation being mainly over the southern zones late Friday into
Highly amplified pattern is continuing to draw cold middle and low
level air south from the Bering Sea into the northern Pacific and
then into the Gulf of the on the back side of the numerous lows
tracking northeast into the Gulf. End result will be temperatures
trending below normal for much of the upcoming week. Temperatures during
the days will be getting warm enough for rain, but overnight lows
will still be falling near or below freezing such that snow is
still very much a part of the long range forecast. Accumulations
mostly late at night and remaining below advisory levels. One
timeframe to watch for potential significant snowfall will be on
Tuesday/Tuesday night as the frontal wave discussed above tracks
over the Panhandle.
European model (ecmwf) continues to be the model of choice, hence little in the way
of changes from yesterday's long range forecast. Overall
confidence is above average.
Marine...Gale Warning for pkz041>043-051.
Small Craft Advisory for pkz012-022-033-035-036-052.
Small Craft Advisory due to seas for pkz053.