textproduct: Eureka

SYNOPSIS

Stratus remains over the coastal areas as eddies offshore recirculate flow back to the shoreline. An upper level low approaches the area Monday, bringing light rain and cooler temperatures with gusty winds. Chances for thunderstorms increase Tuesday and Wednesday.

DISCUSSION

Returning stratus is persistent thanks to the coastal eddies recirculating surface flow back into the lower elevation coastal areas. Stratus is persistent near Humboldt bay and as far inland as a few miles east of Blue Lake. This evening into Monday early morning will fill in as the next low pressure system approaches.

A few convective cells have popped up over Trinity, and the Yolla Bolly district. NBM shows CAPE values in the 900-1000 j/kg near Weaverville and up the Trinity horn this evening. It is more likely that there will be a few showers and lightning in isolated areas of Trinity county which will lose energy by 03-04z. The past few days we have had cells producing showers and lightning but they have waned by 01-02z, mostly in Trinity. The approaching low has a 70-80% probability of producing rain accumulation > 0.03inches in Del Norte Monday and around a 35-45% chance for > 0.03inches in northern Humboldt, also on Monday. The back side of the approaching low will prime the atmosphere for more convective activity. Trinity county looks to have modest CAPE Tuesday and Lake County has gusty winds and low CAPE values Wednesday afternoon. The timing on Wednesday with the gusty winds and CAPE could produce some thunderstorms. Confidence is low to moderate. See the Fire Weather discussion below. /EYS

AVIATION...(18Z TAFs)

IFR to MVFR conditions are likely to continue for the coastal areas through the evening. Interior areas are likely to clear this afternoon with VFR conditions expected. This evening and overnight, stratus will build back in for the coastal areas with LIFR to IFR ceilings expected. IFR to MVFR stratus is possible again for UKI tonight as south winds and a deep marine layer return cloud cover. JB

MARINE

Winds and seas have eased with generally light southerly winds expected today and Monday. Seas are dominated by decaying northerly winds waves and a long period NW swell at around 3 to 5 ft. A weak cold front arrives Monday evening and winds and seas are expected to rapidly increase as strong NW winds fill in behind the front. Expect these to build substantially through the week, especially for the southern outer waters where there is an 80-100% probability of gale force winds developing by Tuesday. A mid period NW swell arrives Tuesday, peaking at around 12 ft. This swell along with building steep northerly wind waves could bring significant wave heights over 15 ft by Wednesday. Winds are likely to remain strong for much of the next week. JB

FIRE WEATHER

Late afternoon convection in Trinity county and the Yolla Bollys are expected again today as atmospheric dynamics prime the conditions for convection. Colder air approaches with the low pressure system, expected to arrive Monday. Not enough CAPE for activation Monday but values increase Tuesday for Trinity County and Wednesday for Lake. Sustained winds around 24mph with gusts up to 35mph late Tuesday evening pick up again Wednesday afternoon for both Trinity and Lake. Modest CAPE Wednesday has good timing with the gusty winds in Lake county for zones 418 and 421. RH values will be around 25% at their lowest with wet convective cells rather than dry which lowers the risk of fire spreading if starts happen from lightning with fuels not being quite cured. /EYS

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory from 9 PM Monday to 3 AM PDT Wednesday for PZZ450-455-470-475.