textproduct: Eureka

SYNOPSIS

Persistent high pressure aloft will remain through the week. Inland areas are subject to abnormally hot temperatures of through the week. Offshore winds in Oregon will transport wildfire smoke to the coastal waters, potentially arriving to the North Coast this evening.

DISCUSSION

A steady ridge of high pressure continues to impact the west this week leading to warm to VERY hot temperatures for the inland areas. Most inland valleys can expect high temperatures between 100-110deg F through the work week. The coast continues to offer some relief from this heat. Forecast confidence in cooler afternoon temperatures is increasing by the minute as satellite observations show a surge of coastal stratus/fog moving northward flowing through a coastal eddy. The current location is near the apex of Cape Mendocino. If this surge continues into Humboldt Co., the streak of warm weather days >67deg will most likely come to an end here in Eureka. It is important to note that areas slightly higher in elevation and farther north than Humboldt Bay could remain warmer through the afternoon.

In addition to the possible fog arriving from the south, increasing smoke is also possible. The previously mentioned coastal eddy is diverting the majority of smoke away from the North Coast as of midday Tuesday. According to multiple rapid refresh models, this coastal feature is expected to be enhanced even more this afternoon into the evening, keeping a majority of smoke off the coast of the area and increasing the low cloud coverage.

The weather pattern will have minimal changes through the week as this high pressure is expected to remain overhead. A slight change in weather is possible this weekend. Cluster and deterministic global model analysis shows this high pressure ridge beginning to weaken through the weekend leading to zonal or even slight upper level troughing entering next week. Until then however, expect warm interior temperatures and foggy nighttime hours along the coast.

AVIATION

VFR is expected through the morning for most area terminals. Stratus continues to surge up the coast near Mendocino County while smoke from OR flows down into the area. Smoke is expected to arrive first to North Coast terminals possibly decreasing surface and slant visibilities. Overcast conditions are expected to develop along the coast overnight with IFR likely (>60%) and LIFR possible (~50%). Inland terminals should remain mostly VFR with gusty afternoon winds and the increased potential for density altitude concerns due to very hot surface temperatures.

MARINE

Northerly winds have been flowing over the far outer waters through the morning. As a result, seas have begun to slowly ease. A localized southerly surge of winds and stratus/fog has begun its journey northward and is currently near the southern tip of Humboldt Bay. This is expected to continue through the evening with stronger southerly winds along the coastal areas. These are expected to be around 10 to 15 kt, but there could be local areas of 25 kt near the Capes. Generally light southerly winds and decreasing northerly waves are expected on Wednesday and Thursday as well. Friday and into the weekend northerly winds are expected to return to the area. Gales are possible over the weekend into early next week.

FIRE WEATHER

Light, offshore flow aloft is expected to weaken this afternoon into tonight. Afternoon RH values are expected to dip into the low teens or single digits this afternoon. Terrain focused winds are expected with upvalley flow for most of the river valleys mixing with southerly general winds.

EKA WATCHES/WARNINGS/ADVISORIES

CA... Heat Advisory until 11 PM PDT this evening for CAZ102-110- 111-113-114-118>120.

Heat Advisory until 11 PM PDT Thursday for CAZ105-106-108- 116-117.

NORTHWEST CALIFORNIA COASTAL WATERS... Hazardous Seas Warning until 3 PM PDT this afternoon for PZZ470.

Small Craft Advisory until 9 PM PDT this evening for PZZ475.