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. && $$ Visit US at http://www.Weather.Gov/Eureka Follow US on facebook and twitter at: http://www.Facebook.Com/US.Nationalweatherservice.Eureka.Gov http://www.Twitter.Com/nwseureka