Scientific Forecaster Discussion

NWS Discussion
			
				

Area forecast discussion 
National Weather Service Eureka California 
323 PM PDT Thursday may 23 2013 


Synopsis... 
cool air will continue to flow into northwest California through 
Thursday. Interior areas will not be as cold tonight. A little light 
rain will be possible at early Friday morning and again Saturday 
night north of Trinidad otherwise it is looking like a dry weekend. A 
more widespread rain will arrive Monday. 


&& 


Discussion... 
temperatures on average are running 5 to 10 degrees warmer than 
yesterday inland, and conditions are a bit milder on the coast as 
well. Surface high pressure ridging has actually shifted northward into 
southern Oregon today as the upper low centered over Washington state 
continues to fill. This has helped promote mostly sunny skies all 
the way up the coast, just about to Cape Blanco. The north coast 
interior has seen some cumulus build-ups over the higher terrain 
with daytime heating. Suspect there could still be an isolated 
shower over the Siskiyous of eastern del norte or eastern Humboldt County 
early this evening. Kbhx radar has not picked up anything...so if 
there are any weak showers out there now, they are being overshot 
because the tops are so low. 


The final shortwave rounding the upper low will approach the north 
coast this evening but as the low continues to fill, any 
precipitation will need to be forced in the shallow moisture and 
instability with onshore flow within a few thousand feet of the 
surface. As the boundary layer stabilizes overnight near the coast 
suspect that anything that does develop from perhaps Orick northward 
may be in the form of light drizzle. This could linger into early 
Friday morning...otherwise Friday is looking like another mostly 
sunny and dry day with slightly warmer temperatures. That said, it 
will still be cold across the interior tonight, though not as cold 
as last night. Issued a frost advisory for Trinity County. Guidance 
indicates that temperatures should be at least cold enough for frost 
there...and perhaps in the deeper valleys of northern Mendocino and 
eastern Humboldt County as well. 


The weekend generally looks dry although there will be a pesky 
trough moving through Saturday night into Sunday morning. Thinking 
there will be enough subsidence and dry air in the lower levels to 
limit showers to near the Oregon border. Better shot at isolated 
showers and maybe even a rumble of thunder will be with any 
build-ups over the Siskiyous or yolla bollys. 


A more defined storm system will approach Sunday night. Models are 
converging on a period of widespread rainfall...perhaps over a 
half-inch...centered on Monday. Not ideal barbecue weather 
unfortunately. 


&& 


Aviation...VFR conditions, clear to partly cloudy skies and light 
to moderate winds will continue at kcec, kacv and kuki through the 
early evening. Moderate to moderate and gusty winds will continue 
through the early evening near the coast then light to calm winds 
will prevail across kcec, kacv and kuki overnight tonight and early 
Friday morning. Cloudiness will increase overnight at kcec and kacv 
reducing ceilings, however ceilings will remain at VFR conditions. 


&& 


Marine...the pressure gradient will continue to relax and 
subsequently the winds and seas will gradually diminish across the 
waters through this weekend. Light to moderate winds and moderate 
seas will prevail across the waters Friday through early next week. 


&& 


Eka watches/warnings/advisories... 
California...frost advisory from 2 am to 8 am PDT Friday caz004. 


Northwest California coastal waters...none. 
&& 


$$ 


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