textproduct: Eureka

SYNOPSIS

Rain through Wednesday, especially for the North Coast. Near freezing to freezing low temperatures expected to return late week. More rain possible late weekend.

DISCUSSION

Rain is making its way southward along the Pacific Coast. A rainy morning is expected for the North Coast with a period of moderate rainfall around midday as a frontal boundary passes overhead. Rain totals are expected to be around 1.00" for Del Norte Co. and slightly less for Humboldt Co. Lighter precipitation is forecasted for Trinity and Northern Mendocino Co. Trace amounts of rain (<0.10") expected for Lake and southern Mendocino Co. Strong southerly winds will develop along the North Coast before this frontal boundary passing. After this frontal boundary in Lake Co., while there might not be much in terms of rainfall, strong winds are forecasted to develop, especially for the higher terrain.

This cold front will advect much colder air over the region. Snow levels drop in response down to ~1,500ft for Trinity Co. and ~2,00ft for Humboldt Co. This drop is not expected to create much snow as much of the precipitation will be over by this time. What this colder air will do is increase the likelihood for frost/freeze conditions for the entire area on Thursday and Friday. 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.

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 rainbeginning on Saturday evening. What these models also show is more widespread rainfall over the area with precipitation accumulations up to0.50" in Lake and southern Mendocino counties. DS

AVIATION

A cold front will swoop across the area on Wednesday bringing MVFR and occasional IFR cigs and vsby's in light to moderate rain. Initially southerly and southeasterly winds in advance of the front will maintain mostly MVFR conditions. Conditions will initially deteriorate at KCEC with reduced vsby in rain and S-SW gusts to around 30 kt. IFR conditions will then spread southward to KACV by 16Z with about a 30% chance of vsby from 1 to 2SM and IFR cigs in light to moderate rain. A push of moist and gusty NW winds behind the front will keep the threat for IFR conditions and light rain going into the afternoon hours. For UKI, generally VFR is expected with bountiful cloud cover and gusty afternoon and evening N-NW winds. Surface wind decouples late in the evening on Wed and potential for low level wind shear will increase as robust N-NE wind flow develops 1000-2500 AGL.

MARINE

A vigorous cold frontal boundary will move across the coastal waters on Wed. Southerly and southwest winds with gusts to 25-30 kt will develop early in the morning and then rapidly shift around to N and NW behind the front in the late morning and early afternoon across the northern waters. Widespread seas building to 6 feet or higher are limited on Wed. There are indications from the NWPS model of localized pockets of steep waves from 6 to 8 feet mostly north of Trinidad by early afternoon for the inner and outer waters. Therefore an advisory has been issued even with limited areal coverage of steep wave over 6 ft. An advisory based on wind gusts from 25 to 30 kt appears more solid, but errors in the wind gust forecast could be as much 10 kt. Just about all the mesoscale models have gusts over 21 kt over a sufficiently large enough area to warrant an advisory for small craft. Northerly winds strengthen and steep wave build Wed evening and overnight, especially south of Cape Mendo. Thus, an advisory has been posted for the inner waters south of Cape Mendo. Gale force winds will be possible (30% chance) as early as Wed evening. Greater coverage and longer duration of gale gusts holds off til Thu afternoon and evening - per the HREF. Thus a gale watch has been hoisted for the southern waters. Seas will build to max heights Thu afternoon thru Thu night. Steep waves are projected to reach 11-13 feet for the southern waters and 9-11 feet in the northern waters. Seas may remain steep and elevated on Fri, however a downward trend will commence and continue into Sat. Another front will approach over the weekend and could bring another bout of gusty winds.

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory from 7 AM this morning to 5 AM PDT Friday for PZZ450.

Small Craft Advisory from 7 PM this evening to 2 PM PDT Thursday for PZZ455.

Gale Watch from Thursday afternoon through late Thursday night for PZZ455.

Small Craft Advisory from 5 AM early this morning to 5 AM PDT Friday for PZZ470.

Small Craft Advisory from 3 PM this afternoon to 5 AM PDT Thursday for PZZ475.

Gale Watch from late tonight through late Thursday night for PZZ475.