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fxus66 keka 200130 
afdeka 


Area forecast discussion 
National Weather Service Eureka California 
530 PM PST Wednesday Nov 19 2008 


Synopsis...an approaching low pressure system and associated cold 
front will bring a general cooling trend and rain to northwest 
California by morning. The best chance of rain will occur north of 
Cape Mendocino Thursday morning. A general drying trend is expected 
by the weekend after a slight chance of showers Saturday morning. 


&& 


Short term...tonight through Saturday...infrared satellite continues to 
shows high clouds streaming over northwest California today ahead of 
an approaching upper level disturbance. The associated cold front 
now crossing 135w will reach the coast by morning. This cold front 
will bring rain to the coast by late Wednesday night into Thursday 
morning. The main energy with this upper level system will cross the 
Pacific northwest...the highest probability of rain will still be north of 
the cape with a chance of rain south. Precipitation will turn showery and 
taper off fairly quickly by Thursday afternoon and evening as the 
trough moves east of the region. A weak trough will move across the 
West Coast Friday evening and bring a chance of showers near the 
Oregon border. Mkn 


Long term...Saturday night through Wednesday...the medium range 
models are showing decent agreement through Monday...with a weak 
trough moving inland Saturday night followed by ridging on Sunday. 
Another upper trough is forecast to approach the West Coast rather 
quickly on Monday...although the GFS splits the flow with a closed 
low developing in the southern branch while the European model (ecmwf) simply 
maintains a baggy trough. The GFS is about 6 hours slower than the 
ec as well...as expected with a more developed system. Kept probability of precipitation in 
the chance category for the Tuesday period...and maintained the 
trend through Wednesday. CMC 




&& 


Aviation...satellite imagery this afternooon shows cirrus as well 
as low level clouds streaming over the area out ahead of the cold 
front that will pass over the area tomorrow morning. Coastal 
ceilings and visibilities will be tricky this afternoon in advance of the 
front. Generally expect ceilings to remain IFR this afternoon with a 
trend toward LIFR overnight and in the morning hours. Rain 
associated with the frontal boundary is expected to arrive around 
11z and should keep ceilings at kacv and kcec IFR or worse through 
the end of the period. Low cloud cover and showers associated with 
the front will obstruct mountainous terrain so flight in these areas 
should be done with caution. Winds will increase overnight with 
gusts to near 18 kts along the coast and gusts reaching 25 kts in 
higher terrain. Koeneke 


&& 


Marine...winds will be on the increase overnight as a cold front 
approaches the coast. Southerly winds will peak tomorrow morning in 
advance of the front with gusts to near 30 kts over the northern 
outer waters. The Small Craft Advisory for winds in this area 
remains in effect accordingly. Winds will then gradually switch to 
the north and diminish as weak high pressure builds in over the 
northern California coast. But...as this high interacts with a 
thermal trough over California on Friday expect winds in the 
southern outer waters to increase to near 25 kts prompting another 
Wind Advisory. Models are not in good agreement toward the beginning 
of next week with respect to wind so no significant changes have 
been made to the forecast. Seas will be on the increase tomorrow 
with a peak in swell height tomorrow night of about 13 feet in the 
outer waters. The periods should not fall below 12 seconds so not 
expecting a need for a hazardous seas warning. Seas are then 
expected to remain around 10 to 11 feet through the end of the 
weekend. The Small Craft Advisory for hazardous seas may need to be 
extended tomorrow accordingly. Koeneke 
&& 


Eka watches/warnings/advisories...none. 


Pt St George to Cape Mendocino 10 to 60 nm 


Small Craft Advisory for winds remains in effect from midnight 
tonight to 4 PM PST Thursday. 
Small Craft Advisory for hazardous seas in effect from 4 am Thursday 
to 10 am PST Friday. 




Pt St George to Cape Mendocino out 10 nm 
Cape Mendocino to pt Arena out 10 nm 
Cape Mendocino to pt Arena 10 to 60 nm 


Small Craft Advisory for hazardous seas in effect from 10 am 
Thursday to 10 am PST Friday. 




&& 


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