textproduct: Eureka

SYNOPSIS

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

DISCUSSION

A few showers and isolated thunderstorms will be possible over the higher terrain of Mendocino, Lake, and Trinity counties this afternoon as a shortwave increases moisture over the region. As this shortwave moves through tonight it may bring some drizzle to coastal areas. Another round of showers and thunderstorms is likely on Sunday as the shortwave continues to bring cool air aloft and instability to the interior. Recent model runs show Sunday as having the more activity than today, 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.

The other concern in the forecast is the potential for some frost in interior valley locations of northeastern Mendocino and Trinity counties particularly Sunday and Monday mornings. Temperatures are forecast to fall into the mid-30s but abundant moisture may increase valley cloud cover and limit fog formation, particularly tonight. Frost advisories may be needed.

AVIATION

Most areas across Northwest California have cleared out around midday today through western Mendocino remains solidly locked in the stratus deck. Periods of MVFR ceilings are possible at all three terminals today as transient waves of clouds move through the area. However, in general VFR is likely to prevail, especially at CEC and ACV. With plenty of moisture around and light winds tonight it is highly likely that the stratus will redevelop and expand across the region impacting all three sites. A deepening marine layer and even lighter winds on Sunday may make clearing more difficult with the potential for an MVFR ceiling along the entire coast through the day. /RPA

MARINE

North winds are expected to persist over much of the coastal waters for the foreseeable future, except for a few southerly eddies occurring near the immediate coast during the overnight hours. Northerlies today are just strong enough to warrant a small craft advisory for the outer waters where steep seas are likely to exceed criteria. Otherwise winds and seas are expected to remain lower for areas within 20 nm of the coast through the weekend.

As a trough moves inland Tuesday into mid next week, northerly winds will increase with the potential for near gale to gales returning mid to late week. /RPA

EKA WATCHES/WARNINGS/ADVISORIES

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