857 
fxak67 pajk 071334 
afdajk 


Southeast Alaska forecast discussion 
National Weather Service Juneau Alaska 
534 am akdt Tuesday Oct 7 2008 


Short term...clearing across much of the southern Panhandle as 
the low to the south continues to move east across central 
British Columbia. Mostly clear conditions over night across the 
Panhandle has brought several areas over the north central Inner 
Channels their killing frost for the year. Surrounding zones had 
frost advisories issued. 


There is a weakening low over the northern Gulf south of the 
kenia peninsula that will persist and slowly weaken through 
Tuesday night. A trough/front has organized a collection of 
showers into a band that is moving east-northeast over the Gulf. 
Earlier there were some lightning strikes being reported along 
the northeast Gulf Coast area. There is still some instability 
along the coast through early Tuesday morning so have kept the 
mention of isolated thunder in the coastal waters mainly to the 
west of the Sitka area (042-043)... while some heavier showers 
may spread onshore through middle day am not expecting thunder 
during that time frame. There is however quite a bit of cooler 
temperatures aloft spreading over eastern Gulf so the possibility 
of sleet (ice pellets) in some of the showers would not be 
unexpected over Southeast Alaska. This trough should lift through 
the area by Tuesday evening leaving just scattered to occasional 
showers from the Gulf spreading onshore overnight. 




Long term...large scale trough at 500h extends from near the pole 
to over a line from Barrow to over Middleton Island and S. This 
trough has enough amplitude to provide cold advection to the Gulf of Alaska 
from a source region in Russia and the northern half of the Bering Sea. 
Large scale pattern is progressive and the trough will migrate east of 
Panhandle about 12z Wed, with a second trough digging S from the Bering 
and into the npac Thursday. The combination of the digging trough 
and the cold advection is discussed below as associated with 
a 980 mb low near Adak at 00z Thursday. 


The digging trough will support an increasing thermal contrast 
and strong baroclinic waves to tracking NE into the glfalsk, and 
the model consensus has improved. The precursor of these waves 
shows up at 00z Thursday a 980 mb low near Adak that should have a 
cold fnt xtdg S for about 1000 nm. This cold front is the leading 
edge of a large scale cold air mass from Russia that will be spreading 
southeast. A wave traveling north along this cold front will mature 
and general a triple pt low moving north-northwest over Kodiak about 12z Friday. Note 
the winds including gales to reach our forecast domain Friday. 


Ajk watches/warnings/advisories... 
public...freeze warning until 8 am akdt this morning for 
akz020-021-024-025. Frost advisory until 8 am akdt this morning 
for akz018-019-022-023. 
Marine...Small Craft Advisory for pkz022-036-041>043-051-052. 


Bezenek/jbt 

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