551 
fxus66 keka 181204 
afdeka 


Area forecast discussion 
National Weather Service Eureka California 
504 am PDT Friday Jul 18 2008 


Synopsis...a slightly warmer day is expected inland today as 
weak high pressure aloft builds over the area. Little change is 
expected along the coast and low marine clouds and fog linger 
through the day. An upper level trough will slowly approach 
northern California over the weekend...maintaining coastal clouds 
along with a cooling trend inland into early next week. 


&& 


Short term...weak shortwave ridge will develop over the region 
today...leading to temperatures a few degrees warmer today and 
Saturday than in the past few days. With the building ridge...the 
marine layer will be further suppressed...which should help erode 
stratus back to all but the immediate coast today by early 
afternoon. Near coastal locations are trickier and have continued 
with a persistence forecast at the coast for today with stratus 
generally remaining in place for most of the day. Partial clearing 
can be expected in some locations...especially where local eddies 
set up downwind of coastal headlands. 


Models are depicting the inital shortwave trough splitting just to 
the west of the coast with the initial wave of energy going just 
to our north Saturday afternoon. Have kept the silent probability of precipitation over 
the far eastern mountains on Saturday as this energy moves th 
rough. Model timing on the southern portion of this trough continues 
to be a bit of a moving target as the timing for all the models 
continues to shift slower...with the sharp trough/closed low now 
moving through Monday into Tuesday. With a strong blocking ridge 
building over the central Continental U.S. Into Canada...the slower trend 
seems to fit well and wouldn't be surprised to see a slower shift 
in later model runs. With the trough in the vicinity through early 
next week...have continued with the low thunderstorms chances for Sunday 
and Monday afternoon over the Trinity Alps. 


Long term...Tuesday through Thursday...not much change in the 
long term forecast...a blocked long-wave pattern sets up as a 
broad upper ridge builds over central United States with near 
permanent presence of upper troughing over Pacific northwest waters and 
West Coast. This suggests slightly cooler than...to near normal 
temperatures over inland areas overall from Monday Onward. The 
monsoon over the Desert Southwest will have to be watched closely 
for the possibility of occasional intrusions of moisture 
circulating around the western periphery of the upper ridge 
sneaking northward. =Alm 


&& 


Aviation...low stratus will continue to bring IFR conditions to 
coastal sites today through Saturday morning. The main threat will 
be low ceilings. Inland sites will continue to have VFR conditions. 


&& 


Marine...north winds will continue to increase over the outer 
coastal waters today as high pressure builds over the 
northeast Pacific and low pressure persists inland. Winds will 
strengthen to gale force across the outer waters by Friday afternoon 
as the gradient between high and low tightens. Models continue to 
show the winds increasing equally over the northern and southern 
outer waters for the start of the gales and hazardous seas. Mkn 


&& 


Eka watches/warnings/advisories... 


Gale Warning from 3 PM this afternoon to 11 PM PDT Saturday for 
pzz470-475. 


Hazardous seas warning from 11 PM Saturday to 5 am PDT Sunday for 
pzz470-475. 


Small Craft Advisory until 3 PM PDT this afternoon for pzz470-475. 


Small Craft Advisory until 8 PM PDT Saturday for pzz455. 


&& 


$$ 


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