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Area forecast discussion 
southcentral and southwest Alaska 
200 PM akdt Wednesday Oct 15 2008 


Analysis and upper levels... 
a positively tilted trough remains extended from the northeast corner 
of Alaska toward Bristol Bay. A vertically stacked low is moving from 
the Kamchatka peninsula toward the western Bering Sea. A large upper 
level ridge separates these two features in the central Bering Sea. 
At the surface...a frontal boundary extends from Prince William Sound 
southwest over the Alaska Peninsula then west toward the vertically 
stacked low near Kamchatka. Several weak lows are present along this 
frontal boundary. 


Model discussion... 
12z models are in fair agreement in the short term. Was not impressed 
with either the GFS or NAM initialization of the shortwave in the 
northern Gulf. NAM has significantly overdone the precipitation over 
southcentral today. GFS has shown some better consistency...therefore 
very little changes were made to the forecast for the first several 
periods. A trend toward the 12z GFS was used through early in the 
weekend. The extended forecast was left alone which was based off of 
HPC guidance. 


Short term forecast... 
southcentral... 
the concern for the short term was the chance of precipitation this 
afternoon and evening and what form that precipitation was going to 
fall. Critical thickness lines dissect the Anchorage bowl and western 
Kenai Peninsula while temperatures have been hovering near freezing 
since early this morning. Although the NAM was advertising 
significant amount of precipitation over Anchorage this 
afternoon...radar and satellite are not showing any indication of 
development. We have backed off on precipitation this evening based on the 
current trends. Beyond the first period...the forecast becomes much 
more clear. Weak low pressure will remain over the Gulf of Alaska 
through the weekend so showers will persist along the coast. For the 
most part...inland areas will see partly cloudy skies with weak 
easterly shortwaves throwing the occasional wrench in the forecast. 


Overnight and early morning fog also may become more prevalent. Any 
clearing coupled with the fresh snowfall will lead to an environment 
conducive to the formation of late night and early morning fog. 


Southwest... 
dry air is finally beginning to filter south across the southwest 
interior. Similarly...the clearing is leading to stratus and fog in 
the lower valleys. Otherwise expecting fair weather through the 
weekend. 


Bering Sea/Aleutians... 
a series of weak impulses will move from the northwest to 
southeast...undercutting the upper level ridge over the northern 
Bering Sea. For the most part...winds will remain Small Craft 
Advisory or less. The exception will be a low that will tap some of 
the Arctic airmass and bring some colder air southward across the 
central Bering Sea on Friday. Gale force winds are likely on the 
backside of this low. 


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


Ab Oct 08 

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