048 
fxak67 pajk 201430 
afdajk 


Southeast Alaska forecast discussion 
National Weather Service Juneau Alaska 
530 am akst Thursday Nov 20 2008 


Short term...the vertically stacked low over the central Gulf 
of Alaska continues to persist today and tonight although it 
begins to drift more to the northeast early Friday morning. The 
associated weather front with this low has pushed onshore over 
the Prince William Sound but curves back south-southeast between 
Cape Suckling and Icy Bay and runs South West of Queen 
charlotte's and Vancouver Island. A low far to the south will 
make land fall over Washington state today with while small waves 
run northward along the boundary. As it slowly drifts eastward. 


It is expected that the downslope over a good portion of the 
northern Panhandle will be overcome by this afternoon light rain 
or snow will start to fall this afternoon and evening. 


Meanwhile a low over the central Pacific will continue to develop 
and will advance towards the Queen Charlotte islands early Friday. 


For the grids used primarily the 00z GFS for adjustment in the 
short range forecast periods. 


Have kept the Wind Advisory for gusty winds out of interior pass 
of the Yakutat zone till midday and a little long for the Skagway 
area. The pressure gradients responsible for these are expected to 
diminish through the day and the gust should weaken through the 
day. 




Long term...two large-scale troughs aloft will be associated with 
two cyclogenetic systems described below. These troughs are 
identified by using the GFS five wave. The second large-scale 
trough aloft and low will be the stronger wind event and should 
occur Sunday. 


A large-scale trough aloft extends S from over pafg and Biorka Island 
to the npac and then to the SW to about 600 nm northwest of Hawaii. We will 
call this trough one. GOES infrared shows cloudmass associated with 997 mb low 
900 nm S of Cold Bay. A frontal wave to the NE of this low, currently 
about 1000 nm S of Kodiak, will intensify to 984 mb as it tracks NE across 
the Queen Charlottes and then NE across Prince Rupert Friday. We will 
call this low one, and with such a track should not raise winds 
above Small Craft Advisory in our forecast domain. 


A second large-scale trough aloft extends from near the pole and S to 
Japan. This wave will propigate east across the Bering Sea this 
weekend and about 00z Tuesday will extend south-southeast from over St Lawrence Island 
and Sand Point. This trough aloft will be the parent feature for 
a large cyclogenetic system tracking NE into the eastern Gulf of Alaska 
sun. Note the marine forecasts include storm force winds in the 
eastern Gulf of Alaska with this system. 


Consensus between 200000z GFS and 190000z European model (ecmwf) holds up well through 
at least 00z sun. This consensus seems associated with the ease 
of the models getting a lock on the first large-scale trough aloft. 
The consensus is poorer for the track and depth of the second low 
for sun and Sun night. 




Ajk watches/warnings/advisories... 
public...Wind Advisory until 3 PM akst this afternoon for akz018. 
Wind Advisory until noon akst today for akz017. 
Marine...Gale Warning for pkz011>013-022-043-051-052. 
Small Craft Advisory for pkz021-031>036-041-042. 


$$ 


Bezenek/jbt 

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