textproduct: Eureka

SYNOPSIS

Near freezing to freezing low temperatures expected to return late week. Breezy winds forecasted for Lake County through the end of the week. More rain expected late weekend into next week.

DISCUSSION

Generally, rain has ended for NW CA. This frontal system will now force northerly winds throughout the region as the front moves southeasterly and cold air fills into the area. In general, coastal areas and higher terrain locations will be gustier. Through Thursday morning and especially in the afternoon, strong northerlies will develop in Lake County for the higher terrain areas in the eastern and southern portions of the county.

Due to this frontal passage, much colder and drier air will advect over the region. In response, snow levels drop down to ~1,500ft for Trinity Co. and ~2,000ft for Humboldt Co. This drop did not create much snow for areas outside of the mountains in northern Trinity Co. However, this colder air will increase the likelihood for frost/freeze conditions for the entire area overnight through the week. Observations show temperatures plummeting due to lack of insulating cloud coverage for the interior areas. NBM data shows the interior valleys are forecasted to get colder than 30F Thursday and Friday mornings. As growing season begins, it is recommended to cover sensitive plants and take other precautions to protect agricultural property these mornings. Thursday morning, Freeze Warnings have been issued for some of the coldest interior valleys, along with Frost Advisories for most coastal areas.

The GFS and ECMWF are both signaling for another frontal storm arriving this weekend. The GFS ensemble shows light rain Sunday with heavier rain possible on Monday. The EPS shows almost the same, with rain beginning on Saturday evening. What these models also show is more widespread rainfall over the area with precipitation accumulations up to 0.75" at lake level in Lake county and in the valleys of southern Mendocino counties. JLW&DS

AVIATION

Robust N-NE winds 1000 to 2000 feet AGL will develop tonight into early Thursday morning in the wake of a cold front. Low level wind shear and shallow turbulence are expected, especially around KUKI by 08Z. Gusty northerly winds are forecast to quickly mix down during the morning hours on Thursday at coastal aerodromes. Peak wind gusts around 30 kt are forecast by afternoon at both KACV and KCEC. Turbulent and rough conditions are probable for small and light weight aircraft. Otherwise, strong subsidence in the wake of a cold front has been resulting in clearing skies Wednesday night. VFR is expected to continue to prevail through the day on Thursday at all forecast terminals.

MARINE

Vigorous cold front has been producing gusty northerly winds Wednesday evening. Wind gusts were close to gale at buoy #14 NW of Pt Arena with gusts to 33 kt. Elsewhere, northerlies have been sub-gale, gusting to 22-30 kt. Seas have also built to hazardous levels for small vessels, 8 to 9 ft at 8 to 9 seconds. Therefore, the advisories for small craft are on the mark for the remainder of tonight. High resolution mesoscale models, GFS and NBM all indicate northerly winds increasing to gales for mostly the southern waters on Thu. GFS and NBM also indicate gale gusts developing in the afternoon for the northern waters. Thus, a gale warning has been hoisted for the northern outer waters for gusts to 35 kt and steep waves around 11 feet at 8-10 seconds. Steep waves will also continue to build through the day on Thursday and peak Thursday night. Max significant wave heights are projected to hit 13 feet in the southern waters and 11 feet in the northern waters. On Friday, elevated seas will steadily subside through the day as winds diminish below gale. By Saturday, a lighter wind regime is forecast as an offshore frontal system breaks down the offshore ridge. Moderate southerly breezes are forecast to develop in advance of the front Sat night into Sunday. Borderline advisory level winds will be possible (40% chance) with gusts over 22 kt on Sunday.

EKA WATCHES/WARNINGS/ADVISORIES

CA... Frost Advisory until 9 AM PDT this morning for CAZ101-103- 104-109-112.

Freeze Warning until 9 AM PDT this morning for CAZ102- 105>108-110-111-113>115.

NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 5 AM PDT Friday for PZZ450.

Small Craft Advisory until 1 PM PDT this afternoon for PZZ455.

Gale Warning from 1 PM this afternoon to 5 AM PDT Friday for PZZ455.

Small Craft Advisory until 4 PM PDT this afternoon for PZZ470.

Gale Warning from 4 PM this afternoon to 5 AM PDT Friday for PZZ470.

Small Craft Advisory until 5 AM PDT early this morning for PZZ475.

Gale Warning from 5 AM early this morning to 5 AM PDT Friday for PZZ475.