Area Forecast Discussion

SYNOPSIS

Dry weather is expected Thursday and Friday with chilly overnight temperatures and moderate sunny afternoons. A few rain showers and interior thunderstorms are possible this weekend and into early next week.

DISCUSSION

High pressure is building in across the area and showers continue to diminish, although widespread CU persists. This afternoon there is expected to be an increase in showers over the inland mountains. Any showers that do form should be fairly weak. Tonight some of the interior valleys may see low clouds and/or fog. Valleys that do remain clear will be likely to see near freezing or freezing temperatures. For now it looks areas well away from the coast may see freezing temperatures. So have issued a freeze warning to Trinity, northern Mendocino, and northern Lake county. Have also issued a frost advisory for the remainder of Mendocino and Lake counties and much of Humboldt and Del Norte counties. After a chilly start on Thursday temperatures are expected to warm quickly to around 70 in most of the interior valleys while lingering around 60 at the coast. Thursday night into Friday a few of the inland could see some frost, but at this point it looks like it will mainly be in Trinity county, northeastern Mendocino, and northern Lake counties. Highs Friday are expected to continue warming into the 70s.

For the weekend and into early next week a general trough over the west coast is expected to keep temperatures near or below seasonal normals. Saturday an upper level low is moving southeast along the northern Rockies while a second upper low is approaching the central CA coast. There is still a lot of uncertainty on the track and speed of these lows, but it looks like there is the potential for a few thunderstorms over the interior and a slight chance of showers over portions of the area. This pattern looks become more of a general open wave trough Sunday and Monday, although surface weather conditions should remain fairly similar. Even with the trough remaining over the area for several days the probability of over an inch of rain for the 3 days ending Tuesday is less than 50 percent. Inland temperatures are expected to be in the 60s. At the coast this will likely keep the marine layer disturbed enough for quite a bit of sunshine at the coast. At some around the middle of next week the ridge is expected to start building into the area once again. Timing is still uncertain on when this ridge builds back into the area. MKK

AVIATION

High pressure is building in across the area and showers continue to diminish. This afternoon there is expected to be an increase in showers over the inland mountains. Any showers that do form should be fairly weak. Tonight some of the interior valleys may see low clouds and/or fog. At KUKI there is less than a 25 percent chance of an MVFR or lower CIG form. It is possible some areas along the coast will also see low clouds develop, but at this point it looks like KACV and KCEC will remain VFR for much of the night. Thursday northwest winds are expected to increase along the coast in the afternoon to 10 to 20 kt with some gusts to 25 kt. MKK

MARINE

High pressure is building in and winds are becoming northerly and starting to increase. These winds are expected to remain less than 10 kt north of Cape Mendocino with 10 to 15 kt south of the cape this evening. Late tonight and Thursday north to northwest winds are expected to gradually increase through the day. There is general model agreement of the winds reach 15 to 20 kt by late afternoon. Stronger winds are expected in the lee of Cape Mendocino where local winds of 25 to 30 kt are expected with a few local gale force gusts. The wind driven waves are expected to build to around 8 feet by Thursday evening south of Cape Mendocino. These will combine with a lingering northwest swell that is slowly diminishing.

Friday the stronger northerly winds are expected to push off the coast as an upper level trough approaches the area for the weekend. For the weekend there is some uncertainty on how much the winds will diminish. Currently it generally looks like the winds remain around 10 to 20 kt, but there is certainly the potential for winds to be lighter. Confidence is higher that Monday will see lighter winds. Mid-week it looks like high pressure starts to return and bring stronger winds again. MKK

EKA WATCHES / WARNINGS / ADVISORIES

CA... Frost Advisory from 2 AM to 8 AM PDT Thursday for CAZ102>106-109-110-112-113-118>120.

Freeze Warning from 2 AM to 8 AM PDT Thursday for CAZ108- 111-114-117.

NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory from 2 PM Thursday to 2 AM PDT Friday for PZZ455.

Small Craft Advisory from 8 AM Thursday to 5 AM PDT Friday for PZZ475.