textproduct: Eureka

SYNOPSIS

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

DISCUSSION

An area of low pressure approaches the area today, which is currently only bringing a few high clouds to the area. Generally, similar conditions are expected today compared to yesterday, with highs in the 70s and 80s for much of the interior and highs in the high 50s to low 60s for the coastal areas. Overnight temperatures are likely to similar, if not a degree or two warmer, than this morning's 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 Monday afternoon. High- resolution models are focusing precipitation at 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 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 pulse of moisture moves through the Pacific Northwest Tuesday night into Wednesday. Southerly winds will increase ahead of the main frontal passage Wednesday morning. Much 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 to 2.5 inches for Humboldt and Del Norte Counties, around 1.0 to 2.0 inches in Trinity, and around 0.5 to 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, dropping from over 6,500 ft Tuesday afternoon to 5,000 to 5,500 ft Wednesday morning. 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 will increase as we get closer to this event. Stay tuned! JB

AVIATION

Generally VFR conditions are place across the area this afternoon. There are a few low clouds lingering around Humboldt Bay this afternoon, but even these are dissipating quickly. If skies clear completely, as it appears they will, it will likely stay clear through at least midnight and possibly much of the night. The models are showing some stratus develop along the Humboldt coast later tonight, but not specifically at KACV or KCEC. So for now have some stratus in the TAF for KACV through mid morning. There may be some clouds up the river valleys near the coast, otherwise VFR conditions are expected. For the afternoon skies are expected to be VFR, however there is the potential for a shower or two in the afternoon. MKK

MARINE

Northerly winds have started to increase again and are expected to continue to increase to around 15 to 25 kt off the coast. Closer to the coast there may be a few gusts close to 25 kt, but the short period waves are expected to make it into the northern inner waters. So the SCA remains in place there. The waves are currently a combination of wind driven waves and an 8 or ten second swell. These are combined into one wave group in the forecast and may be difficult to distinguish at times. There is also a small 14 second northwest swell, but that is only building to around 3 feet.

Monday afternoon and overnight winds are expected to quickly diminish as the stronger winds push farther off the coast due to a front approaching the area. Tuesday winds will generally be less than 10 kt through at least through early afternoon. Seas are expected to diminish as well.

Tuesday in the evening and overnight southerly winds are expected to increase. These are expected to increase to strong to near gale force by Wednesday morning. There is still some uncertainty on how how quickly these will increase. The general consensus is they The will peak Wednesday around mid-morning, but a few a of the models show a peak Tuesday night with a second peak Wednesday morning. 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.

Wednesday night through late in the week northerly winds are expected to return and increase to near gale or gale by Friday. Thursday a larger swell is expected to build into the waters peaking around 13 feet at 12 seconds on Thursday. This look to include the short period waves from the strong winds. MKK

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory from 9 PM this evening to 11 AM PDT Monday for PZZ450.

Small Craft Advisory until 7 PM PDT Monday for PZZ470.

Small Craft Advisory until noon PDT Monday for PZZ475.