Post Mountain, CA 96041 Weather

Key messages

* Dry weather is expected this afternoon through Thursday. Rain chances return Friday into the weekend.

* Frost and near-freezing temperatures possible for the interior valleys and possibly near the coast tonight.

* Minor coastal flooding expected through Thursday at high tide, mainly around Humboldt Bay.

Synopsis

Cool and dry weather is expected through Friday with additional chances for light rain late Friday and over the weekend. High tides this week are likely to cause areas of coastal flooding for areas around Humboldt Bay.

Discussion

Dry and cool air is gradually building in behind a passing cold front. Frosty conditions are likely for many interior valleys by early sunrise. That said, extensive valley fog visible on satellite may keep conditions warmer than initially forecast, at least for Humboldt and Trinity counties. Skies are remaining more clear in Mendocino. Cold nights continue for the coming days with chances for frost and near-to-below freezing temperatures possible for the interior valleys, and even close to the coast. High temperatures also remain chilly in the 50s and low 60s.

The troughing pattern remains in place for the remainder of the week, but generally remains dry through Friday. Onshore flow will most likely help a weak, diurnal marine layer reforms, especial.lya round Humboldt Bay, as soon as Wednesday night. The only exception to this would be in Del Norte County on Friday, where there is roughly a 20% of light rain that currently may only amount to a few hundredths with the bulk of precipitation to the north.

This low off the coast of Oregon moves southward this weekend, though there is some uncertainty on just how much moisture will arrive and how far south the low will drop. There is a widespread near 50% chance of any measurable rain on Saturday for all of NW California. The chance for wetting rain (over 0.1") is around 20- 30%. There is still a low chance (15%) of over a half inch of precipitation. This system is a cold system, and snow levels may drop to around 3000 to 4000 ft. Moisture is limited, but a dusting of snow in the higher terrain of Trinity County may be possible.

While over a week out at this point, long range ensemble members show a decently confident signal in a shift towards a more significant wetter pattern mid to late next week. CPC is highlighting NW California as having a moderate risk of heavy precipitation between 11/6 and 11/8 and a slight risk continuing through 11/10. Exact timing and rain amounts will become clearer over the coming days. Stay tuned! /JB, JHW

Aviation

06Z UPDATE: Dry but still unstable air behind a passing cold front has allowed for VFR conditions to persist overnight. High resolution models indicate some scattered MVFR ceilings are possible (20%) near shore by sunrise. Besides some IFR fog in interior valleys VFR conditions will persist. A weak marine layer is more likely to return to the coast Wednesday night, withs some potential (40% chance) of IFR ceilings. /JHW

Marine

Strong northerly winds have build into the southern outer waters with gusts near gale force. Winds will remain strong and intermittently push into the inner waters over the next couple of days. Short period seas will build close to 10 feet by early Wednesday afternoon. North winds have remained much more moderate in the northern waters. North winds will persist until early Friday when they diminish into the weekend. Beyond short period seas, various minor mid period westerly swell will argument the sea state through the week. /JHW

Coastal flooding

Water levels Tuesday 9.26 ft above MLLW at the North Spit. This brought some minor flooding to low lying areas of King Salmon and the Arcata bottoms. This was again with an anomaly of 1.2 to 1.3 feet above astronomical tides. The surge model shows a similar anomaly on Wednesday, despite winds turning more northerly. So with an astronomical high tide of 8.06 feet on Wednesday, expect water levels between 9.1 and 9.3 with similar impacts to Tuesday's flooding. A Coastal Flood Advisory has been reissued for Wednesday afternoon for Humboldt Bay.

Arena Cove is also expected to see water level reach the highest astronomical tide levels. Waves are only expected to be around 6 to 7 feet at 11 seconds likely limiting the impacts for the Mendocino coast at this point, yet it will continue to be monitored for any changes.

Watches, warnings and advisories

CA: Coastal Flood Advisory from noon today to 3 PM PDT this afternoon for CAZ103.

Frost Advisory until 9 AM PDT this morning for CAZ105-106- 113-118.

Freeze Warning until 9 AM PDT this morning for CAZ110-111- 114.

NORTHWEST CALIFORNIA COASTAL WATERS: Coastal Flood Advisory from noon today to 3 PM PDT this afternoon for PZZ415.

Small Craft Advisory until 3 AM PDT Thursday for PZZ455-475.