textproduct: Eureka

KEY MESSAGES

* A passing cold front brings a high chance of light rain to Del Norte and northern Humboldt late Thursday night into Friday.

* Gusty winds late Thursday and into Friday.

* Dry conditions and gusty winds will bring elevated fire weather conditions to Southern Mendocino, Lake counties and areas of Trinity County Thursday afternoon. * Cooler temperatures will arrive this weekend behind the front, bringing chances for isolated interior frost.

SYNOPSIS

An approaching cold front introduces more extensive cloud cover and a chance for measurable rain to Del Norte and northern Humboldt counties late Thursday night into Friday. Colder temperatures will follow through the weekend. Gusty winds associated with the front will bring elevated fire weather conditions to Lake County Thursday afternoon.

DISCUSSION

A trough with a compact and deepening surface low will near the region, clipping NW CA late Thursday. Though there will be some strong dynamics with the storm system, the track as trended farther north on recent model guidance. This will limit the impacts and total measurable rainfall. The best shot of light rain will be from Del Norte to Northern Humboldt. Chances for anything over 0.1 inches quickly lower to zero south or east of Cape Mendocino.

The interior ridges will see some gusty winds from the stronger winds aloft with the trough. There is a high chance (70%) for gusts to exceed 30 mph coastal and interior ridges of Del Norte late Thursday into Friday morning. Chances for gusts over 25 mph and locally up to 30 mph are also high for south Mendocino and Lake counties Thursday afternoon. This will create some fire weather concerns for those areas due to the drier conditions.

A colder air mass will arrive overnight Friday. This will bring the potential for frost for some of the interior valleys. Chances for chilly temperatures and frost will continue into at least early next week. A trough will pass through Sunday. This storm system and a shortwave disturbance preceding it Saturday will be mostly dry, but could bring an afternoon shower or two for the interior. The extended outlook looks to remain dry with no chance for wetting rainfall.

AVIATION...00Z TAFs

The weakened inversion and continued northerly winds allowed for stratus to quickly mix out Wednesday. Though a trough will approach the area Tuesday, Subsidence ahead of it has quickly compressed the inversion, with afternoon observations showing the ceilings down to 200 ft. This increases confidence for LIFY conditoions fog through Thursday morning for the coastal terminals. Light winds will persist into Friday morning. VFR conditions will persist elsewhere apart for some potential stratus pushing into the Fort Bragg area.

MARINE

A trough approaching from the west will begin to slowly weaken the northerlies tonight as small mid period NW swells remain. A strong area of low pressure will pass by well offshore Thursday. Though the W to SW winds will remain relatively light, there will a strong westerly wind fetch around the low which will drive in a quick pulse of steep west northwesterly seas around 9-11 ft at 10-11 seconds for most of the waters. Seas may reach hazardous levels at 12 ft for the far NW waters out around 30 to 60 NM. These seas will increase rapidly late Thursday through Friday morning and will bring dangerous conditions to small crafts. The northerlies will restrengthen Friday afternoon, and will be near gale to gale strength in at least the outer waters by Saturday.

FIRE WEATHER

A trough and surface low will clip the region Thursday. Light precipitation is expected from around Cape Mendocino and northward through northern Humboldt and Del Norte, with no precipitation expected south and east of the cape. This storm system will increase westerly winds Thursday afternoon and into Friday. RH will be on the rise with the moist flow, but there will be a period of near to locally critical fire weather conditions Thursday afternoon in southern Trinity, southern Mendocino, and Lake County (zones 411, 416, 419, 420, and 421). Recoveries will be good overnight Thursday. Northerly to westerly winds will turn gusty Friday while RH remains higher. A pronounced offshore wind surge will then develop Friday night, drying out the interior somewhat Saturday with min RH dropping to the low 20 to upper teens. The extended forecast does not include any more chances for wetting rain.

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory from 2 AM to 5 PM PDT Friday for PZZ450.

Small Craft Advisory until 9 PM PDT this evening for PZZ455.

Small Craft Advisory from 11 PM Thursday to 5 PM PDT Friday for PZZ470.

Small Craft Advisory until 3 AM PDT Thursday for PZZ475.

Small Craft Advisory from 5 AM to 5 PM PDT Friday for PZZ475.