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Area forecast discussion 
southcentral and southwest Alaska 
130 PM akdt Friday Jul 4 2008 


Model discussion... 
models have come into better agreement as the transition from a 
Bering Sea trough to a Gulf trough is underway. A NAM/GFS blend was 
used in the short term while the extended forecast remains unchanged. 


Analysis and upper levels... 
two areas of low pressure at the surface rotating around the broad 
upper level cyclonic circulation. Multiple upper level vortices 
rotating around the upper low located just south of the eastern 
Aleutians. Thermal trough building near the Alaska Range which will 
be the focus of much of our attention the next couple of days. 


Short term forecast... 
southcentral Alaska... 
cumulus building along the Alaska Range early this afternoon. 
Anticipating shower and thunderstorm coverage to increase this 
afternoon from previous days. Cloudy skies and scattered showers 
still affecting much of the coastal areas while the interior is 
slowly clearing out. The thermal ridge will strengthen as it moves 
over southcentral tomorrow. An easterly wave will help initiate 
shower and thunderstorm activity. Will mention thunderstorms in all 
zones north of the Kenai Peninsula and Prince William Sound. The 
clearing this afternoon north and east of the forecast area is a good 
indication that tomorrow will be partly cloudy in the 
morning...allowing for rapid surface heating and maximum afternoon 
instability. Saturday night...expect convection to become more 
stratiform and then stabilize again by Sunday morning. Sunday 
afternoon should be another active convective day although the 
thermal trough should retreat a bit north...limiting the thunderstorm 
coverage to north of Anchorage and matsu valley. 


Southwest Alaska... 
similar weather outlook for southwest Alaska as instability will 
increase each day with the thermal trough moving over the area. 
Tomorrow is looking to be very active with numerous showers and 
thunderstorms developing in the afternoon and moving southwest during 
the evening. The potential is there for a mesoscale convective 
complex to develop in the upper Kuskokwim and maintain its intensity 
overnight as it moves southwest toward the Delta. 


The thermal trough weakens the next several days but remains in the 
general area of the Kuskokwim vally so anticipate partly cloudy 
mornings with isolated to scattered afternoon thunderstorms through 
early next week. 


Bering Sea...low pressure system finally moving south of the Aleutian 
Islands and into the western Gulf tonight. High pressure will build 
into the western Bering Sea overnight. Widespread fog will remain a 
problem through the weekend and early next week in this area. 


Extended...models seem to be zeroing in on another stacked low moving 
out of eastern Siberia and into the western Bering Sea middle next week. 
High pressure will shift to the Alaska Peninsula while a broad area 
of low pressure remains in the southern Gulf. 


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


Ab Jun 08 

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