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Area forecast discussion 
southcentral and southwest Alaska 
140 PM akdt sun Mar 21 2010 


Analysis and upper levels... 
high amplitude trough over eastern Siberia resulting in a downstream 
ridge centered over the western Bering Sea. A broad trough persists 
over much of Mainland Alaska with the anchor low located well south 
of our forecast area over the North Pacific. At the surface...high 
pressure continues to dominate the eastern Bering Sea...surrounded by 
two weak surface troughs with little to no precipitation associated 
with them. 


Model discussion... 
models have been inconsistent with the weak surface pattern although 
upper levels and synoptically looking similar. The 12z runs are in 
fair agreement...although give a slight edge to the NAM based on run 
to run consistency and continuity. 


Short term forecast... 
precipitation limited to the coastal areas this afternoon. The 
coverage will increase overnight as a short wave rotates southward 
out of Bristol Bay into the western Gulf of Alaska. At the same 
time...another short wave is dropping out of the northern Yukon 
territory. The two short waves coupled with some jet support from the 
northern Pacific will help develop a surface low Monday that will 
bring gale force winds along the north Gulf Coast Monday night. 
Clouds and precipitation should remain along the coastal sections and 
upslope mountain ranges but can not rule out a stray shower over 
inland areas given the weak pressure pattern and abundance of 
cyclonic circulation aloft. 


The mostly cloudy and showery regime continues through middle week while 
the upper pattern makes very little progress...maintaining the long 
wave axis near the Alaska Peninsula. 


Southwest Alaska... 
likewise will see generally increasing clouds with scattered showers 
through early next week. Temperatures will remain at or above 
climatological norm for this time of year. The weak pressure gradient 
and abundant low level moisture could lend itself to extensive fog 
along the coast and in low lying areas. 


Aleutians/Bering Sea... 
a storm force front is approaching the western Aleutians but will 
weaken rapidly as it encounters the high pressure over the central 
Bering Sea. A weak surface occlusion will develop along the weakening 
boundary around the central Aleutians Tuesday...and then continue to 
fill as it becomes a vertically stacked low near the Alaska Peninsula 
by middle week. 


Aer/alu...watch/warning summary 
public...none. 
Marine...Storm Warning 176 
Gale Warning 172 175. 
Fire weather...none. 


Ab Mar 10 

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