textproduct: Eureka

SYNOPSIS

A weakening frontal system will bring a cooling trend with isolated showers to the region today and Tuesday. Widespread rain is expected Tuesday night into Wednesday followed by lingering showers into Thursday.

DISCUSSION

Overnight temperatures are likely to similar to yestereday's morning low temperatures. Generally, lows in the mid 30s to low 40s are expected for most interior valleys, with 40s likely along the coastal areas. Light showers are forecast to move in this afternoon. High- resolution models are focusing precipitation towards southern Humboldt, northern Mendocino and Trinity counties, though there is some model spread that brings rain both further south and further north. Regardless, these showers will remain light to locally moderate with little to no impacts expected. Additional showers are likely through Tuesday, though there is greater spread and less forecast confidence on where these showers will develop. Interior areas in Mendocino and Lake are most likely to see these showers, but confidence remains low.

A stronger frontal system moves through the PacNW Tuesday night into Wednesday. Southerly winds will increase ahead of the main frontal passage Wednesday morning. Much of elevated terrain of Del Norte and the higher terrain in Humboldt have over 50% chances to see gusts over 40 mph. Localized gusts of over 50 mph are possible over the highest terrain. Lake County may also see strong gusts, with a broad 30% chance for gusts over 40 mph at lake level. The higher elevations, including the Cobb area, have much higher probabilities.

Widespread light to moderate rain is likely across the area. Periods of heavy rain are possible for the North Coast, and especially in the King Range and the mountains of Del Norte and northern Humboldt. Total rain amounts range from around 1.5-2.5" for Humboldt and Del Norte counties, around 1.0-2.0" in Trinity, and around 0.5-1.0" inches in Mendocino and Lake Counties. This will largely be beneficial rain, but some minor impacts (flooding in poor drainage areas and mud/rock slides) are possible in Humboldt and Del Norte with the heaviest rain. Snow levels will drop with this system, down to 5,000-5,500 ft Wednesday morning during the period of most precipitation. This will bring some snow down to Scott Mountain Pass. Snow totals there range from around 2 to 6 inches, depending on how low snow levels drop.

Stratiform rain turns showery Wednesday night into Thursday. Snow levels continue to drop into Thursday, and could be as low as 3,000 ft.While precipitation is likely to be meager by this point, some light snowfall is possible on the highest passes of Highways 3, 36, and 299 in Trinity County. Additionally, with much colder air aloft, instability will increase, particularly along the coast. Showers capable of producing accumulating small hail are possible, along with isolated thunderstorms. Confidence on the details of this hazard will increase as we get closer to this event. Stay tuned! JB

AVIATION...(30/06Z TAFs)

Mainly VFR conditions with mid- to high- level clouds streaming across the area from the west. High-res model guidance suggest low clouds redeveloping around Humboldt Bay and along the Eel river valley after 7Z. There is a 25-35% chance for IFR/LIFR ceilings in ACV between 9Z-14Z. Otherwise, VFR conditions are expected through the period at all terminals, with a PROB30 of light showers for the coastal terminals between 21Z-24Z. Surface winds will be generally WNW at 5-10 kts during the afternoon hours at ACV and CEC, while very light and variable for UKI. /ZVS

MARINE

Northerly winds will continue to increase across the water into Monday, with fresh to strong breezes in the outer waters and moderate to fresh in the inner waters. This will result in steep- short period waves around 6-9 feet through Monday, promoting hazardous conditions for small crafts. A small craft advisory is in effect through Monday for zones 450 and 475, and for zone 470 through Monday night. Steep waves will persist into Monday evening and then subside by Tuesday morning as northerly winds diminish.

Winds will turn southerly and strengthen Tuesday night with strong to near gale gusts late Tuesday night through Wednesday as a front approaches from the NW. There is the potential for gale force gusts in the northern waters. The forecast remains lower than this, but it is possible and will need to be monitored. A large steep seas peaking to around 13 feet at 12 seconds is forecast to build in the wake of the front on Thursday. /ZVS

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 11 AM PDT this morning for PZZ450.

Small Craft Advisory until 7 PM PDT this evening for PZZ470.

Small Craft Advisory until 4 PM PDT this afternoon for PZZ475.