textproduct: Eureka

KEY MESSAGES

* High pressure offshore builds through Monday, increasing northerly winds.

* High pressure is expected to bring warmer temperatures and dry weather Monday and Tuesday.

* Cooler temperatures and a 5 to 10 percent chance of thunderstorms in Trinity county are expected Wednesday afternoon and overnight.

SYNOPSIS

Surface high pressure building offshore will strengthen the onshore pressure gradient against the interior thermal low into early this week. Expect a shallow marine layer pinned along the coast while the interior valleys have dry, seasonably warm. conditions. For Wednesday, an evolving upper low will bring cooler temperatures and slight chance for interior thunderstorms.

DISCUSSION

An upper level trough is moving out of the area early this morning as weak upper level ridging slightly begins to dominate the weather pattern for the early week. Clear skies late night will have the potential to fog over for some inland valleys by dawn if temperatures get low enough. No widespread frost is expected for the interior due to the increased potential for fog. Monday and Tuesday temperatures warm up again in the inland areas. After today's highs in the 70s inland temperatures are expected to warm by 10 degrees in many areas with highs in the mid 80s to low 90s Monday and slightly warmer on Tuesday. Coastal areas are likely to see a clear, yet breezy afternoon which will keep temperatures relatively tame in the mid to upper 60s.

Midweek, a change in the weather pattern is expected. An upper level trough is predicted to form near British Columbia before ending up over NW CA. This synoptic feature has yet to be formed, leading to a fairly high degree of forecast uncertainty at the moment. Once the trough that has been over the area from the weekend moves eastward, this feature is likely to form and forecast certainty should increase much more from there on out.

That said, this predicted feature and its resulting pattern will likely be too dry and weak to produce meaningful rain. However, a few convective showers are possible in the evening, especially for the Salmon and Klamath mountains. There is some instability already modeled increasing the potential for a thunderstorm if the moisture is ample enough. Besides the faint storm potential, this system will keep temperatures slightly below normal for most of the forecast area. End of the coming week looks like warmer temps return as this upper trough exits the area.

AVIATION

Northerly winds for exposed terrain and calm winds elsewhere with VFR is expected for all areas tonight as slight offshore winds continue to flow. Overcast conditions are being seen developing near FOT, yet this is not expected to make it ACV or CEC. If this level does form, northerlies will mix this layer out early, yet any coverage has been discontinued from the TAFs due to decreasing confidence. Inland areas can expect terrain influenced wind with VFR through the first half of the week.

MARINE

High pressure continues to build into the area. As a result, winds will shift to the northwest and then more northerly through the overnight hours into Monday morning. These are expected to increase to around 25 to 30 by Monday afternoon with the stronger winds in the southern waters and far northern outer waters. A few gale force gusts are possible in localized areas in the lee of the capes, yet at this point they are not expected to be widespread enough to warrant a gale warning. The winds do make their way into the southern inner waters Monday afternoon, and will likely push farther offshore Monday night. The northern inner waters are not expected to see widespread winds over 20 kt to warrant a small craft advisory, but the steep short period seas could exceed 6 feet and this may require a small craft advisory.

For Wednesday, winds and seas are expected to rapidly diminish in the evening and overnight, but this may still change slightly. A small upper level trough is dropping south over the area and a small shift in the storm track could change the winds substantially. Thursday and Friday, fairly light southerly winds are expected before northerly winds return and start to increase for the weekend. MKK

FIRE WEATHER

High pressure building off the coast will bring a warming and drying trend across Northwest California through Tuesday. Breezy north to northwest winds will develop across the ridges and exposed interior valleys this afternoon and Monday afternoon with local gusts between 15 and 25 miles per hour. Locally stronger winds and lower RH recovery are expected in eastern Lake county early Monday. Wednesday afternoon or overnight an upper low has the potential to bring a few thunderstorms to Trinity county.

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory from noon today to 3 AM PDT Tuesday for PZZ455.

Small Craft Advisory until 3 AM PDT Wednesday for PZZ470.

Small Craft Advisory until 3 AM PDT Wednesday for PZZ475.