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Area forecast discussion 
southcentral and southwest Alaska 
500 PM akdt Thursday Aug 21 2008 


Model discussion...models are in general agreement on synoptic scale 
systems in the short term. The 12z ecmwf(ec) has shown the most run 
to run consistency and looks relatively reasonable. Strong North 
Pacific jet and differences in the handing of upper trough account 
for significant differences in surface solutions beyond day 3. Last 
couple of model runs in this time frame have been internally 
inconsistent. All said...confidence is low beyond day 3. 


Upper levels...broad trough extends from a weak low center over the 
eastern Bering Sea to over the northern Gulf of Alaska. Things 
consolidate some over the Gulf of Alaska/NE Pacific Friday and Sat as 
the as the upper centers shift to that region and holds for a couple 
days. This will likely prove problematic in forecasting sensible 
weather as numerous short waves...associated with Gulf complex... 
rotate across the southern Mainland over the next couple of days. 
Trough will continue over the Alaska Peninsula and eastern Bering Sea through 
the weekend. 


Surface short term forecast... 
a broad and weak trough with several minor low centers extend from 
the Bering Sea to over the northern Gulf/Copper River basin. Expect 
we will see a more consolidated pattern Friday and Sat over the Gulf as 
a low center moving into the NE Pacific moves to the northern Gulf. 
However...with the broad upper trough...weaker surface centers will 
be a bit difficult to forecast. The pattern shifts from a 
concentration of energy in the Gulf to a broad low pressure trough 
over much of the southern Mainland sun. Unsettled weather will be the 
general rule over much of the Mainland forecast areas. However... 
areas of low clouds and fog likely especially over the eastern Bering 
Sea and coastal locals. May see some evening thunderstorms over SW 
Alaska this evening. Thunderstorms also possible over the Copper 
River and again over SW Alaska on Sat. Stability indices are 
marginal...so isolated thunderstorms would be worst case. High 
pressure ridge over the western Bering Sea will continue low clouds 
over the region. 


Long term forecast...confidence if relatively low with differing 
model solutions and run to run consistency. HPC graphics with a lean 
toward ec ensemble means day 6-8 look probably best guess for now. 


Aer/alu...watch/warning summary 
public...none. 
Marine...none. 
Fire weather...none. 


Rmc Aug 08 

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