Gale Warning 122, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
605 AM AKDT Wed Mar 29 2017

.SHORT TERM...today through Wednesday night. South to Southwest
flow aloft is the story over all of the AK Panhandle today. The
embedded waves in this flow will bring periods of enhanced
rainfall over the region in this wet pattern which will persist
through Wednesday night.

The main change in the forecast stems from a wave developing just
south of the Gulf of Alaska this afternoon which will move into
the southeast Gulf tonight. This will not bring a big change in
the winds but could extend the precipitation later into tonight
across much of SE Alaska and could shorten the break between
systems Thursday.

Current short term forecasts had some GFS guidance added. NAM also
had a good handle on the developing wave which was more diffuse on
the ECMWF. 06Z model runs of the GFS and NAM were continuing the
development of this feature.

.LONG TERM.../Thursday through Tuesday night/ A high end gale
force low is forecast to enter the western gulf on Thursday. Gale
force winds with the associated front will arrive over outer coast
on Thursday evening and extend from Cape Suckling south pas the
Dixon Entrance. Peak conditions expected on the inside late
Thursday night with gales forecast for Clarence Strait, Sumner
Strait, southern portions of Chatham Strait, and Cross Sound.
Elsewhere on the inside, small craft winds forecast except for
northern Lynn Canal, where a parallel gradient should result in
winds 20 kt or less.

Precipitation from this front will arrive along the outer coast
late Thursday afternoon or Thursday evening. Significant low level
warm air advection associated with this front will push snow
levels higher, limiting snow to the higher elevations of the
highways.

WPC, the 00Z GFS, and the 12Z ECMWF model runs presented moderate
to good agreement at 500 mb on the placement of troughs, short
waves, and upper level ridges. A ridge extending from BC southwest
to coastal waters west of Washington State will become suppressed
over the weekend but then rebuild early next week. Temperatures
from Thursday into Friday were warmed slightly.

Confidence in the extended range forecast is average.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ051-052.
     Small Craft Advisory due to Seas for PKZ022-041>043-053.
&&

EZ/Bezenek/Fritsch

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