textproduct: Eureka

SYNOPSIS

An approaching cold front introduces more extensive cloud cover and light rain to Del Norte and northern Humboldt counties this evening into Friday. Gusty winds associated with the front will bring elevated fire weather conditions to Lake County this afternoon. Colder temperatures will follow through the weekend.

DISCUSSION

A trough with a compact and deepening surface low will near the region, clipping NW CA late this evening. 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. Areas of Del Norte could see periods of moderate rain with around a 50% chance for over 1 inch of total rainfall. 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 coldest interior valleys (particularly Hayfork). 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...(6Z TAFs)

VFR conditions are being observed at all terminals with only high clouds being observed on satellite. Despite clear skies (as of late Wednesday evening), model guidance suggests moderate to high confidence in stratus reforming with LIFR to IFR ceilings likely at CEC and ACV. The highest chances are around sunrise. There is some uncertainty on when the stratus will lift and scatter with southwest flow persisting through the afternoon. There is around a 40% chance stratus persists through the afternoon at ACV and CEC. Some improvement is likely in the evening as a front approaches and winds turn south-southeasterly, however this will be followed by light to locally moderate rainfall for the Humboldt and Del Norte Coasts. Interior areas, including UKI, are likely to remain VFR for the next 24 hours.

MARINE

A trough approaching from the west will weaken the northerlies today. 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 9-12 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 tonight 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 and are likely to continue into early next week.

FIRE WEATHER

A trough and surface low will clip the region today. 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 this 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 Trinity, eastern Mendocino, and Lake Counties. Recoveries will be good overnight tonight, even in areas without rain. Northerly to westerly winds will remain gusty Friday, although RH trends 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 from 11 PM this evening to 5 PM PDT Friday for PZZ470.

Small Craft Advisory until 3 AM PDT early this morning for PZZ475.

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