textproduct: Eureka

SYNOPSIS

Isolated showers and thunderstorms are possible in the interior each afternoon through Monday. Drier weather returns mid next week.

DISCUSSION

Moisture from an upper low off the northern California coast brought a few showers Thursday afternoon. This upper low is moving off the coast towards a secondary upper low and will combine off the central California coast this morning. This positioning of the low by this afternoon will supply slightly more moisture to the area compared to yesterday. A few showers and isolated thunderstorms are possible again in the interior this afternoon, mainly in northern Lake, eastern Mendocino, and eastern Trinity Counties. Little rainfall is expected with these storms, with the highest chance for wetting rain (>0.1") being in eastern Trinity at around 40%. At the coast, the deep marine layer with stratus will likely continue with only partial clearing, if any, expected. A shortwave moving through tonight into Sunday morning may bring drizzle to the coastal areas. This through will continue to bring moisture and instability to the interior, bringing a chance for afternoon showers and thunderstorms. Recent model runs show Sunday as having the more activity than Saturday, but mainly focused in Trinity, interior Humboldt, and interior Del Norte. Wetting rain chances remain the highest (30-50%) in Trinity County and much lower elsewhere. The trough slowly moves out of the area Sunday night into Monday, but some models are showing an additional shortwave or upper low moving through the area Monday afternoon. This could provide enough moisture to continue afternoon shower and isolated thunderstorm activity. Drier and warmer weather is likely to return by mid next week as ridging redevelops. JB

AVIATION

Weaker winds have allowed for a consistent marine layer to persist all along the coast. At the same time, passing low pressure has kept the layer lifted with MVFR ceilings around 1.5 kft. Instability in the marine layer may even allow for some drizzle early in the morning. The marine layer is likely to persist all day Saturday, though there is some chance (35%) of briefly scattering out to VFR. Mostly MVFR conditions will most likely persist Saturday night. Interior conditions are much more uncertain, though MVFR condition chance will increase (40% chance) in the Russian River Valley overnight Saturday as low pressure slowly migrates south and pulls marine air up the valley.

MARINE

Moderate to strong northerly winds have shunted far offshore with near calm winds close to shore. Some steep short period seas have persisted int he outer waters but even those will decay through the day Saturday. Weak low pressure meandering down the coast may even promote a weak southerly wind reversal near shore.

Moderate north winds will briefly push back into the inner water overnight Saturday, very slightly increase seas. Winds will more consistently weaken for early next week with persistent but gentle north winds in all waters. Short period seas will dominate the sea state, but a mid period westerly swell building up to 4 feet will augment seas through the weekend.

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 1 PM PDT Sunday for PZZ470-475.