Weather

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Area forecast discussion 
southcentral and southwest Alaska 
200 PM akdt Sat Oct 11 2008 


Analysis and upper levels...a deep upper trough is situated along 
Alaska's West Coast with a surface low over Kodiak Island and several 
fronts extending from the low to the north and east. Strong northerly 
flow exists across the eastern Bering with high pressure in the 
central Bering and a deepening low west of the Kamchatka peninsula. 


Model discussion...NAM and GFS are similar on the large scale, but 
the NAM is depecting the frontal boundaries and position of the low a 
bit better. The NAM is the slower of the of the two models which also 
fits with current observations. 


Short term forecast...the low over Kodiak Island has several fronts 
extending to the north and east. One such front stretches north 
toward McGrath. Snow will continue along this front as it moves ever 
so slowly east. Another front stretching east just south of the 
eastern Kenai will also take its time lifting north. These fronts 
will produce rain and snow and plenty of wind. Cold air is banked up 
behind the western most front and will slowly seep into southcentral 
on Sunday. 


The low and associated front lifts northeast toward western Prince 
William Sound Sunday afternoon. Much of the precipitation in southcentral 
will start as rain thanks to a downslope component to the wind 
keeping temperatures in the 30s and 40s. Specifically for the Anchorage 
bowl...rain should begin late tonight...then mix with or change to 
snow Sunday afternoon as the low moves into Prince William Sound and 
northwest winds cool the airmass sufficiently. The upper trough 
swings through Monday morning with the snow coming to an end. Snow 
amounts are tricky to predict at this time as an exact changeover 
time is yet to be determined. 


The low weakens as it moves east...but residual moisture hanging 
around as the cold air takes over will change rain showers over to 
snow. Areas along and west of the Parks Highway in the Susitna Valley 
may get another round of heavy snow with a prolonged period of 
upslope flow. Weak high pressure builds in allowing for some clearing 
on Monday ahead of the next front approaching from the Bering. 


Further west...snow will linger along the Alaska/Aleutian ranges 
overnight with clearing skies along the coast with slowly diminishing 
winds. Gale force winds will persist for at least one more night 
along and south of the akpenn. Weak ridging slides east from the 
central Bering as a strong front approaches the western Aleutians 
late tonight. Maximum gale force winds and rain will accompany the front 
as it makes steady progress across the Bering...reaching the SW coast 
by Monday afternoon. 




Aer/alu...watch/warning summary 
public...none. 
Marine...gale 120 125 130 132 150 155 160 165 170 171 172 175 176 179 
180 185 411 412 413 414. 
Fire weather...none. 


Jca 

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