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fxus66 keka 081104 
afdeka 


Area forecast discussion 
National Weather Service Eureka California 
304 am PST Thursday Jan 8 2009 


Synopsis...a weak cold front will bring light rain to northwest 
California this morning...mainly north of Garberville. High pressure 
will build across the northeast Pacific behind the front this 
afternoon and support dry weather across the region into next week. 


&& 


Short term...today through Sunday...satellite imagery shows a 
weakening cold front approaching the California coast early this 
morning. Water vapor and AMSU derived precipitable water shows a 
band of moisture with precipitable water values greater than an inch 
extending into the subtropics but the best dynamics with the front 
remain north of California. The tail end of the front will swing 
through northwest California rather quickly with widespread light rain 
beginning a couple of hours before sunrise and turning to scattered 
showers around noon. Have scaled back probability of precipitation for this 
afternoon/evening and have reduced quantitative precipitation forecast. The airmass following the 
front is not as cold as previous model runs suggested and expect 
the snow levels to only briefly lower to near 4500 feet over del 
norte and Humboldt interior areas later this morning. 


Skies will begin to clear late in the afternoon as high pressure 
will begin to move into the Pacific northwest. Weak offshore flow 
will develop tonight...but do not think the winds will be strong 
enough to prevent the development of patchy fog over night. High 
pressure and offshore flow will persist into next week and support 
clear skies through the weekend. Clear skies combined with a cold 
air mass behind the front will produce cold nights with valley 
fog...and warming daytime temperatures. Th 


Previous long term...Saturday night through Wednesday...high 
confidence in a dry forecast continues for most of the period as 
strong upper level ridging along the West Coast brings 500 mb heights 
some 2 South Dakota above seasonal norms. This pattern will be augmented by 
low level offshore flow so afternoons will be quite mild although 
nighttime lows along the coast and in the interior valleys will be 
cold. Interior Valley highs...especially early in the period in the 
upper Trinity...will be problematic as low level inversions will 
likely restrict temperatures from reaching their maximum potential or even 
MOS numbers. There is some indication of energy slipping under the 
ridge by Wednesday but so far this is a transient and weak feature. 
We will opt to maintain probability of precipitation below mentionable thresholds into 
Wednesday and await better model consensus. Burger 


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Aviation...approaching front will bring light rain with periods of 
MVFR ceilings through around 19z. Scattered rain showers will linger behind the 
front through the remainder of the day with ceilings expected to remain 
VFR. Some turbulence can be expected with breezy southwesterly winds 
ahead of the front becoming northwest in the afternoon. Alm 


&& 


Marine...southwest winds will briefly remain at Small Craft Advisory criteria for 
the next few hours as a quickly moving cold front passes through. 
Winds will quickly turn to the northwest and north later this morning behind 
the front. Strong high pressure building in behind the front over 
the eastern Pacific will tighten the pressure gradient...leading to 
moderate north to NE winds through at least Saturday. Occasional gusts 
to gale force will be possible thur/Fri...especially over the 
southern offshore waters where the gradient will be the strongest. 


Storms moving across the northeast Pacific and locally generated 
swell will continue to produce moderate seas through the remainder 
of the week. 


&& 


Eka watches/warnings/advisories... 
Small Craft Advisory for all waters. 


&& 


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