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Area forecast discussion 
southcentral and southwest Alaska 
400 am akdt Sat Mar 20 2010 


Analysis and upper levels... 
high amplitude blocking ridge engulfs much of the Mainland while a 
neighboring upper level low and accompanying trough cover the Bering 
Sea and the Aleutians. The end result is a split upper level flow 
pattern...with the jet stream either flowing north into the Arctic or 
south into the northeast Pacific...leaving the state relatively nice 
and dry. A vertically stacked low along with its associated clouds 
and precipitation are quickly decaying over the far northern Gulf 
Coast. 


Other surface features include a high pressure ridge creeping south 
over the western Mainland and a broad low over the Sea of 
Okhotsk...which is spitting weak shortwaves across the Bering. The 
remnants of one of these shortwaves is bringing snow showers to 
coastal regions of southwest Alaska...but these are diminishing in 
coverage area and intensity. Much of southwest Alaska and Bristol Bay 
lie in a col...with ridges to the north and south and lows to the 
east and west. 


Model discussion... 
models in good agreement with all major weather features through the 
weekend. Some slight disagreements arise starting on Monday regarding 
the structure and strength of a weak low the spins off into the Gulf. 
Models are also having a tough time agreeing on the strength and 
timing of the associated shortwaves that will wrap up into south 
central Alaska on Tuesday night and Wednesday...with the European model (ecmwf) 
solution the more aggressive (timing and strength-wise) of the bunch. 


Short term forecast... 


South central Alaska...the current Gulf low hangs on for one more 
day as it drifts west-southwest towards Kodiak Island. While the bulk 
of the precipitation has ended...this low could squeeze out a few 
more showers along the southern Kenai Peninsula and Kodiak Island 
before it is all said and done today. Otherwise the weekend looks 
pleasant for south central Alaska...with continuing above normal 
temperatures and clouds diminishing later today. 


Southwest Alaska...a dissipating occluded front is pushing slowly 
inland over southwest Alaska. This system will continue to spread 
snow showers along the Bering coast through the early afternoon 
hours. Snowfall accumulations will be minimal and confined to the 
coast...though a stray snow shower may push further inland. 


Aleutians and Bering Sea...a series of quick shortwaves clip the 
western Aleutians through the weekend and spread light showers over 
the western Bering. A low tracks well south of the Aleutians today 
and tomorrow...though it may spread some light precipitation over the 
central portion of the island chain. Ridging builds in across the 
Bering starting on Monday. 


Long term forecast... 
relatively quiet weather remains in store for next week. A new 
frontal system works across the western Aleutians/Bering 
Sea on Monday and Tuesday before running up against an east Bering 
ridge and dissipating. A low rotating into the Gulf on Wednesday will 
bring another round of precipitation to the northern Gulf Coast. In 
general...with the blocking high holding steadfast through 
mid-week...any significant weather system will track well south of 
the aor. The GFS in particular is hinting at a breakdown in this 
ridging late in the week...so a return to a more active weather 
pattern may be on tap for next weekend. 




Aer/alu...watch/warning summary 
public...none. 
Marine...Gale Warning...170 172 176. 
Heavy freezing spray warning...179. 
Fire weather...none. 


Kansas Mar 10 

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