Point St. George to Cape Mendocino CA out 10 NM Marine Forecast
|Today...S Winds 5 To 10 Kt. Waves Nw 11 Ft At 14 Seconds. Chance Of Showers.|
|Tonight...S Winds 5 To 10 Kt. Waves Nw 10 Ft At 13 Seconds. Chance Of Showers.|
|Sat...Nw Winds 5 To 10 Kt. Waves Nw 9 Ft At 12 Seconds. Slight Chance Of Showers.|
|Sat Night...N Winds 10 To 15 Kt. Waves Nw 8 Ft At 11 Seconds.|
|Sun...N Winds 10 To 20 Kt. Waves N 10 Ft At 9 Seconds.|
|Mon...E Winds 5 To 10 Kt. Waves Nw 6 Ft At 10 Seconds.|
|Tue...Nw Winds 5 Kt. Waves Nw 3 Ft At 8 Seconds...And W 6 Ft At 13 Seconds.|
| Area Forecast Discussion|
National Weather Service Eureka CA
442am PDT Fri September 25 2020
Another weak front will bring increasing clouds and some showers north of Cape Mendocino this afternoon and tonight. A strong ridge of high pressure will result in building inland heat and fire weather concerns this weekend, with very warm temperatures extending to the coast early next week.
A weak cold front will approach from the northwest, with increasing clouds and some showers pushing onshore over Del Norte and northern Humboldt Counties this afternoon and evening. The front will sag southward over the area overnight and rain chances are expected to persist. Rainfall amounts with this front may reach from a tenth to a half inch north of Trinidad, with amounts dropping off quickly to the south and east. Light showers or drizzle may last into the early morning hours of Saturday but should taper off quickly by mid morning as high pressure builds and breezy NW winds develop in the wake of the front for the afternoon and evening. The relative humidity will likely remain sufficiently high in this N-NW flow regime to mitigate the fire weather threat across the area on Saturday. Humidities will start to fall Saturday night as a northerly speed max develops over the Sacramento Valley. Lake County will be on the very edge of these strong north winds. Even so, the RH's really do not plummet until Sunday. Temperatures will also start to warm up on Sunday. The fire weather threat will increase during the day on Sunday and last through Sunday night as the air mass dries out in response to easterly wind flow and large scale sinking. The strongest easterly winds will be over the exposed higher terrain and ridges, with possible gusts up to 30 to 40 mph. The easterly winds will continue into the morning hours of Monday and then diminish through day on Monday.
Strong warming is expected early next week as a massive ridge aloft builds over the area. Ensemble and deterministic guidance continues to indicate record heat for coastal areas as well as the interior valleys. It is within the realm of possibilities for coastal sites to hit 80F or more on Monday and Tuesday. Longer nigheights will likely mitigate the heat risk in the interior, even though high temperatures are expected to peak in the low 100's, about 15-20F above late September normals. The largest unknown factor is the smoke from the wildfires. The offshore flow will blow the smoke westward out toward the coast and over much of the area. The smoke could knock temperatures down by 10 to 20F. The rain we received yesterday is not sufficient to completely extinguish the fires and suspect we will see at least some smoke. How much is highly uncertain at this time and will depend on fire behavior and how active the fires become in response to the very dry conditions and offshore winds.
A blocking ridge aloft will maintain extremely dry conditions with generally above normal temperatures through much of next week. Winds will likely begin to turn back onshore mid to late week, with gradually lowering temperatures, especially near the coast. No rain is expected for the next 7 days under this stable flow regime.
A weak frontal system will allow southerlies to stick around today, but northerlies will redevelop late tonight and really ramp up Saturday afternoon. Gales to near gales are forecast to develop over the outer waters and around Point Saint George and Cape Mendocino starting on Sunday. Issued a Gale Watch for both the outer zones starting Sunday morning. Winds will weaken late on Sunday from south to north and become generally less than 10 knots over all zones by Monday afternoon. Otherwise, the large, northwest swell will slowly diminish through this weekend.
While some light rain will give a tenth to a quarter inch to northern Humboldt and Del Norte later Friday and Friday night, the focus will be on increasingly hot and dry weather later this weekend and early next week. A push of dry northerly winds will spread down the northern Sacramento Valley as high pressure builds in from Oregon Saturday night. These winds may clip portions of Lake County Saturday night. It is now looking like easterly winds should also develop farther north in northeast Mendocino, Trinity, and portions of interior Humboldt county on Sunday, with afternoon humidity dropping into the teens. The combination of locally gusty ridgetop winds, low humidity, and dry fuels may result in locally critical fire weather conditions, mainly across the exposed ridgetops. There is still some question regarding the strength and coverage of these winds, but we do not expect this event to be close to the magnitude of the the fire weather event around September 7th through 9th. Winds will ease on Monday, but hot and dry conditions will persist for much of northwest California, with no rain in sight through the next weekend. /AAD
.BEACH HAZARDS...The first large, northwest swell of the season peaked late yesterday evening. As the swell continues to trend downward, large surf will still be possible through this morning, with surf heigheights up to 15 feet possible through this morning. Have extended the Beach Hazards Statement through noon to reflect the continued surf threat. Surf will continue to trend downward through the rest of today.
.EKA WATCHES/WARNINGS/ADVISORIES... CA...Beach Hazards Statement until noon PDT today for CAZ101-103-104- 109.
Fire Weather Watch from late Saturday night through Monday morning for CAZ212-277-283.
Fire Weather Watch from Saturday evening through Monday morning for CAZ264.
NORTHWEST CALIFORNIA COASTAL WATERS...Gale Watch from Sunday morning through late Sunday night for PZZ470.
Small Craft Advisory until 6am PDT Saturday for PZZ450-470-475.
Small Craft Advisory until 6pm PDT this evening for PZZ455.
Gale Watch from Sunday morning through Sunday evening for PZZ475.