textproduct: Eureka

KEY MESSAGES

* Slight chance (10%) of thunderstorms over the interior and moving towards the coast through Wednesday night.

* Slight chance (10%) of thunderstorms around the Trinity Alps Thursday afternoon.

* Warmer and drier interior temperatures for the interior into the weekend with stronger marine layer along shore.

SYNOPSIS

Cool and moist marine air will peak over the area Thursday alongside a slight chance of thunderstorms in Trinity County. Warmer and drier conditions will rebuild this weekend with shallow marine air along shore.

DISCUSSION

A deep cutoff trough has slowly pushed on land today. This has greatly weakened winds along shore but has otherwise helped slightly cooled conditions across the area. Even the warmest interior valleys have struggled to reach 80. The trough is also generating enhanced instability with broad cumulus formation across the interior this afternoon. Convective models show MUCAPE values of 500 to 1000 J/Kg late this afternoon and through the evening. Moisture is generally lacking, but water vapor shows some moisture accumulation centered around eastern Humboldt. Some High resolution models, particularly the RRFS, show scattered thunderstorms late this afternoon through the evening. Chances are generally only around 10% with the greatest probability over the Yolla Bollys, along South Fork Ridge, near Orleans, and around the Smith River Valley. Any storms that form would be weak with only isolated lightning, weak outflow, and light rain. Storms would move towards the coast with some slight potential of it storms even reaching the coast, especially around Klamath.

A couple models, mostly HRRR, show some isolated storm potential (5% chance) overnight, mostly around the Smith River Valley. Low pressure will continue to meander eastward on Thursday. This will pull some more marine influence near shore with weak southerly wind. Southerly wind may also help pull in some marine fog and clouds closer to the Lost Coast and into the upper Russian River. The chance (10%) of thunderstorms will continue, but the core of instability and thunderstorm chances will shift further east, more focused around the Trinity Alps. The potential near the coast will reduce.

A high pressure ridge will gradually rebuild Friday and into the weekend. This pattern will allow for interior temperatures to dry back out and warm back into the 90s. Moderate north winds will return near shore, helping form a shallow but persistent marine layer especially north of Cape Mendocino. High pressure will most likely persist through next week. Most models show weak to moderate high pressure, but about 20% of ensemble members show unusually strong high pressure around next Tuesday that could push interior highs closer to 100. Aside from isolated showers today and tomorrow There is near 0% chance of wetting rain for the next 10 days. /JHW

MARINE

Low pressure moving inland has weakened northerly wind and pushed strong winds further offshore. Seas have fallen in the inner waters along with the wind and will continue to fall in the outer waters overnight with seas generally below 6 feet by mid Thursday morning. Southerly winds will form along shore in the inner waters early Thursday with gentle gusts staying below 15 kts. Moderate to strong northerly winds will gradually return to the southern waters by Friday and gradually spread north through the weekend, though winds will most likely remain much calmer closer to shore. Short period wind waves will dominate the marine environment with only a very minor southwest mid period swell up to 2 feet to speak of. /JHW

FIRE WEATHER

The thunderstorm risk discussed above is the main fire weather concern over the next 36 hours. This is a chance (10%) of isolated weak thunderstorms over interior Humboldt and Del Norte through Wednesday night with storms moving east tot west towards the coast. There is slight potential for storms late in the night, mostly over the Smith River. Storm potential will remain Thursday, but shift focus towards the Trinity Alps area. Any storms will be weak with light rain. Aside from storms, winds are mostly gentle and terrain driven with generally high RH over 30 percent and good overnight recoveries. Any new starts are not expected to spread rapidly. Conditions will significantly dry and warm over the weekend with thermal belts contributing to much worse RH recovery. There is little to no chance of wetting rain for the next 10 days. /JHW

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 8 PM PDT this evening for PZZ455.

Small Craft Advisory until 3 AM PDT Thursday for PZZ470-475.