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Area forecast discussion 
southcentral and southwest Alaska 
450 am akdt Sat Sep 6 2008 


Analysis and upper levels...deep upper trough situated from the 
eastern Bering into the north central Pacific with an intensifying 
low near 50n 160w. A long fetch of tropical moisture is streaming 
north ahead of the trough spelling plenty of rain for coastal 
locations of southcentral over the weekend. A secondary trough over 
the western Aleutians will slide in behind the first low with a 
continued southwest flow for the southern Mainland. 


Model discussion...the GFS has been pretty consistent and has 
finally fallen in line with the European model (ecmwf) in the latter periods. Only 
minor tweaks were needed in the short term with a full reload with 
the latest GFS from Tuesday through next Saturday. 


Short term forecast...the low near 50n 160w will bottom out around 
986 mb this afternoon as it moves toward the southern end of Kodiak 
Island by Sunday morning. Plenty of gale force winds can be expected 
as this low and its associated front lift northward. Gusty east-West Gap 
winds will increase this afternoon across southcentral and SW Alaska 
as the front approaches...tightening the pressure gradient. Heavy 
rain (as much as 2 inches plus) is expected from Kodiak Island to the 
eastern Kenai Peninsula and western Prince William Sound. With 
saturated ground and rivers running high from rains last week...zone 
125 (western Prince William sound) is under a Flood Watch. The 
initial surge of moisture should make it a ways inland with periods 
of light rain before downslope winds kick in ernest later tonight. 
The Bristol Bay region will see rain encroach from the south this 
afternoon...continuing into the Kuskokwim valley tonight. The 
steadier rains will give way to a showerier regime on Sunday as the 
entire system moves inland and weakens. 


Another low riding around the backside of the Bering Sea trough will 
skirt south of the Aleutians and emerge just west of its predecessor 
crossing the akpenn sometime on Monday. Similar conditions can be 
expected with this system...meaning more east-west gaps winds with plenty 
of gales in the marine zones (both ahead and behind the low) and of 
course plenty of rain. 


Long term forecast...a trough is expected to persist in the eastern 
Bering...which spells more of the same...wet and windy through at 
least mid-week. 




Aer/alu...watch/warning summary 
public...Flood Watch 125. 
Marine...gale 120 125 130 132 138 140 150 155 160 165 351 352. 
Fire weather...none. 


Jca 

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