textproduct: Eureka

KEY MESSAGES

* Red Flag Warning in effect for all towns and areas within Lake County Saturday for critical fire weather of strong winds and low relative humidity.

* Elevated fire danger for all interior areas this afternoon and evening.

* Chances for light rainfall for Del Norte and northern Humboldt this evening and overnight.

* Dry, near-normal conditions return early next week.

SYNOPSIS

Cooler temperatures are expected through into the weekend. Light rain is possible for the Del Norte and northern Humboldt today and tonight. Westerly to northwesterly winds will bring elevated to critical fire danger for the interior this afternoon and evening.

DISCUSSION

A trough and associated front will enter the area today, considerably lowering interior temperatures to the 70s and 80s. The front will also bring a chance for rain to Del Norte and Humboldt Counties. Del Norte has around an 80-90% chance to see measurable rain, while northern Humboldt has around a 30-50% chance. The chance for wetting rain (over 0.1") is around 10-30% in northern Humboldt north of Eureka and 60-80% in Del Norte. There is some instability modeled with this system, which may allow for a thunderstorm to develop in an especially strong shower. Because this will be showery, some areas can see locally higher precipitation, perhaps as high as a half inch in areas of Del Norte.

Post frontal westerly winds will strengthen this afternoon for the eastern portions of the area. Wind gusts of 25 to 40 mph are likely for much eastern Lake County, eastern Mendocino, and the Trinity River Valley in eastern Trinity County. This will elevate fire weather concerns, particularly over Lake County where the strongest winds will coincide with dry conditions. A Red Flag Warning is in effect for Lake County today, but elevated fire weather conditions will exist for all the interior areas listed above. There are also chances this fire threat continues Sunday night and Monday for the far eastern portions of the area. See the Fire Weather section below.

An omega-block pattern is likely to develop right off the Pacific Northwest coast, with troughing remaining far east and far west. Slightly over half of ensemble members do show an elongated positively tilted trough or cutoff low over the area Wednesday. This will contain little moisture and may only result in a slightly deepened marine layer and perhaps some modest instability in the higher terrain. Regardless, a dry, near-normal pattern looks likely for the following week as the omega block stalls the storm track for NW California. /JB

AVIATION...(18Z TAFs)

A front is approaching NW California early this afternoon bringing in mid to high level cloud cover. Breezy west-northwest winds are likely this afternoon and evening over interior areas, including UKI. Winds aloft may continue overnight over Trinity, eastern Mendocino, and Lake Counties which will may lead to areas of low level wind shear and wave cloud activity is already being observed. Generally light rain is likely this evening and overnight for the coastal terminals with MVFR ceilings likely during periods of rain. Brief IFR conditions are possible should a heavier rain shower move near a terminal. The marine layer is likely to remain disrupted as this front moves overhead and widespread stratus reformation is unlikely. /JB

MARINE

An incoming front has weakened northerly winds and seas have subsided significantly. A mid period south swell at around 3-4 ft along with these subsiding wind waves dominate the sea state. South winds will increase this evening and overnight right along the Humboldt and Del Norte Coasts with gusts of 15 to 20 kts. Elsewhere, winds remain light at less than 10 kts through Sunday evening. Sunday night into Monday, northerly winds increase again with near-gale to gale force winds force winds possible for the outer waters by Monday.

FIRE WEATHER

A troughing pattern has brought breezier winds, much cooler temperatures, and a deeper marine layer. Wetting rain is possible for Del Norte and far northern Humboldt. Stronger winds are forecast this afternoon and evening and gusts up to 35 mph are possible in Lake, southern Mendocino, and eastern Trinity Counties, especially for higher, N-S orientated terrain. RH will rise with this onshore push of winds to the 20s and 30s, but much stronger wind gusts of 25 to 35 mph will support critical fire weather conditions, particularly in Lake County. In the few hours before the winds increase, hot and dry conditions are possible, increasing the likelihood of critical fire weather conditions for Lake County. A Red Flag Warning is in effect for Lake County until 2 AM Sunday. Other areas outside Lake County will still see elevated fire danger, including eastern Mendocino and Trinity County, despite not being within the Red Flag Warning area.

Winds ease Sunday and RHs increase slightly into the high 20s to the high 30s for the eastern interior. Areas closer to the coast could see afternoon RHs in the 50s with a much deeper marine layer. Sunday night into Monday, an increase of northerly winds down the Central Valley may elevate fire conditions again for the eastern portions of the area, particularly eastern Lake County should the winds end up on the stronger end. RH does trend upwards, so critical conditions may be localized and brief.

EKA WATCHES/WARNINGS/ADVISORIES

CA... Red Flag Warning until 2 AM PDT Sunday for CAZ418>421.

NORTHWEST CALIFORNIA COASTAL WATERS... None.