453 
fxus66 keka 201244 
afdeka 


Area forecast discussion 
National Weather Service Eureka California 
445 am PST Thursday Nov 20 2008 


Synopsis...an approaching low pressure system and associated cold 
front will continue to bring rain to northwest California this 
morning with showers this afternoon. The best chance of rain will 
be north of Cape Mendocino today. Weak high pressure will bring 
fair skies on Friday...followed by a chance of rain north of the 
cape on Saturday morning as a trough moves through the Pacific 
northwest. 


&& 


Short term...today through Sunday...an approaching cold front is 
currently spreading rain over northwest California. Highest 
rainfall amounts today will be north of Cape Mendocino as the bulk 
of the upper support remains north of the region. Rain will taper 
off to showers quickly by late morning as the shortwave and trough 
axis shift east following frontal passage. Clearing skies tonight 
will lead to a fair start to the day for most of the area Friday 
morning as heights rise over the region. A weakening trough will 
move through the Pacific northwest Friday night...bringing a chance 
of rain north of the cape into Saturday morning. Rainfall amounts 
will be generally less than a tenth of an inch with this system. 
Models are in reasonably good agreement regarding the development of 
a ridge over the West Coast by early Sunday...which will bring dry 
conditions to the area for Sunday. Kl 


Previous long term...Sunday night through Wednesday...an upper low is 
forecast to approach the West Coast Monday through Wednesday. The 
GFS is about 6 hours slower than the ec...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/kl 


&& 


Aviation...satellite imagery shows front off the coast moving about 
35kt. Ahead of it a MVFR band of clouds extends in all areas with 
light rain. Increasing rain and lowering ceilings and visibilities with 
local areas of IFR ceilings with front as it moves through this morning. 
Based on satellite expect back edge of front clouds to move through 
by middle to late morning. Infrared satellite imagery shows cold air 
cumulus...especially over waters off Oregon coast. With onshore flow this 
afternoon...expect VFR ceilings in scattered rain showers...mainly over 
coastal mountains and higher elevation. Ceilings low enough to obscure 
higher terrain. Dean 


&& 


Marine...southerly winds increasing ahead of front and laps shows 
25-30kt in northern outer waters with buoy 27 gusting to 32 knots at 
4am. Southerly winds will peak this 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. 
Once front passes through this morning...the winds will gradually 
switch to the north and diminish as weak high pressure builds in 
over the northern California coast. The tail end of a second weaker 
front moves across northern waters Friday night into Saturday. As 
the high rebuilds and interacts with a thermal trough over 
California on Friday night expect winds in the southern outer waters 
to increase to near 25 kts prompting another Wind Advisory. Models 
coming more in line for winds next week with cut off low and 
associated surface low off of pt Conception. Winds Switch Back to 
southeast Sunday afternoon and increase but stay below Small Craft Advisory. Winds 
then Switch Back to northerly on Thursday. Seas will be on the 
increase today with a peak in swell height tonight about 11-13 feet. 
Looking at buoy 6...seas peaked at 18 feet at 12-14 second periods 
which decays into our waters at 11-12 feet at 15-16 seconds. Swell 
subsides slightly during the day Friday but second swell train from 
low pressure with second front will spread into area Saturday with 
heights more in the 11 feet at 11-12 seconds range. 


&& 


Eka watches/warnings/advisories... 


Small Craft Advisory for winds for Pt St George to Cape Mendocino 
from 10-60 nm out through early this afternoon. 


Small Craft Advisory for hazardous seas for Pt St George to pt Arena 
out 60 nm from this afternoon through Sat afternoon. 


&& 


$$ 


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