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fxak67 pajk 052043 
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Southeast Alaska forecast discussion 
National Weather Service Juneau Alaska 
1243 PM akdt Sat Jul 5 2008 


Short term...at 1800 UTC satellite and radar data indicate the 
band of precipitation over southern Southeast Alaska is becoming 
less organized as it moves northward. Satellite imagery also 
shows the back edge of the higher cloud tops to be near Ketchikan 
and a spotter in that area reported breaks in the clouds to the 
south. The break will be short-lived as scattered showers move 
through the area this afternoon and early tonight. Models 
generally agree that another trough will move into the southern 
Panhandle later tonight. Small craft southeasterly winds will 
persist in the southern outer coastal waters and Clarence Strait 
overnight. Scattered showers will follow the trough on Sunday. 


In the central Panhandle a few precipitation bands will propagate 
through the area this afternoon and then become more organized 
tonight as the trough advances northward. Little precipitation is 
expected in northern sections this afternoon but probabilities 
will increase later tonight as well. 




Long term...hemispheric pattern is five wave becoming four WV 
with planetary scale trough at 500h extending from near the pole 
and S to over Seward and south-southwest over the npac. The change to 
four WV is associated with retrograde of the trough aloft. The next 
ridge downstream is a broad feature over northwest can that gains 
amplitude Tuesday. The large scale vorticity field associated with 
this trough and ridge provides the support for the polar front 
zone generating a significant triple point feature, discussed 
late in the next paragraph, that will result in the Small Craft Advisory winds 
and raised probability of precipitation for the southern Panhandle Tuesday and Tuesday night. 


500h low 250 nm S of Sand Point has persistent large 
scale circulation. It will move east reaching a point 400 nm S of 
Kodiak 12z Mon, when it will begin to move NE and in phase with 
a frontal WV on the polar front zone. The surface low at 12z Tuesday 
should be a 1010 mb 300 nm south-southeast of Cordova, with a mature 
occlusion being sent toward the pnhdl, and sending a triple pt 
NE through Dixon Entrance by 18z Tuesday. This is also why the 
forecast pkg will keep the pattern of the southern Panhandle having higher probability of precipitation 
than the remainder of the forecast domain. 


The GFS and European model (ecmwf) consensus has improved and the spread of the 
naefs ensemble members has remained small enough to narrow enough 
for this senario so the track should include a 1010 mb surface low 
300 nm south-southeast of Cordova is better than yesterday 




&& 


Ajk watches/warnings/advisories... 
public...none. 
Marine...Small Craft Advisory for pkz036-041>043-051-052. 


&& 


$$ 


Cfd/jbt 

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