Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
032 FXUS66 KEKA 151202 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 502 AM PDT Mon Jul 15 2024 .SYNOPSIS...The threat for interior, mostly dry thunderstorms continues today. Areas of coastal dense fog will linger through the morning hours. Temperatures will trend down through mid week and will increase some into the weekend. && .DISCUSSION...Patchy to areas of dense fog developed overnight and are holding through the morning hours. A Dense Fog Advisory was warranted. Improvement is expected through the later morning hours. The area of low pressure responsible for the active interior thunderstorm pattern will extend over N CA today. The lingering monsoonal moisture and increasing forcing will allow for more mostly dry thunderstorm development today and through this evening (15 to 20%). The focus will mainly be in Trinity County, but development may span from Northeast Mendocino, Eastern Humboldt, and perhaps far East Del Norte today. There may be some nocturnal convective development in far NE Trinity county tonight when forcing is maximized over the last sliver of monsoonal moisture. The instability and sounding profiles point toward a chance for strong downburst winds with the thunderstorms. The coastal low will then weaken and become absorbed by a shortwave trough on Tuesday. This system looks to be much drier, and may only briefly increase southerly winds Tuesday afternoon for the interior ridges to enhance fire weather concerns over Trinity County. SREF only holds a very low chance (5%) for thunder north of our forecast area in Siskiyou County on Tuesday. Inland temperatures will trend lower through midweek before the Four Corners high strengthens a bit and expands west. Inland temperatures will likely break 100 again by Saturday in the warmer valleys, including Weaverville, but NBM has trended lower with these values with uncertainty with the arrival of a potential shortwave. There are also some indications additional monsoonal moisture may get wrapped in through the weekend. JJW && .AVIATION...LIFR ceilings and visibilities are being experienced along the coast early this morning. Scattering of stratus is uncertain, and any scattering and VFR conditions would be short lived, as stratus is likely to make a comeback in the evening. Stratus from the south is moving toward UKI, but it looks unlikely it will make it this morning. Any low ceilings will quickly mix out after sunrise. Models are indicating a deeper marine layer tonight, along with stronger overnight southerly winds that could advect stratus over to UKI, bringing IFR/LIFR ceilings. JB && .MARINE...Winds and steep seas have largely subsided across most the waters. The main exception is in the far NW portions of the northern outer waters where northerly gusts of 20 kts are still possible. Southerly breezes are forecast around Cape Mendocino this afternoon, peaking around 10-15 knots. The sea state will be primarily wind wave driven along with a weak long period SW swell. Significant wave heights are forecast to be around 3-6 ft. Southerly gusts pick up slightly Tuesday afternoon, with gusts around 20 knots possible around Cape Mendocino and remaining lighter elsewhere. Breezy northerlies south of Cape Mendocino return Thursday. JB && .FIRE WEATHER...Lingering monsoonal moisture and increasing forcing from a nearing low pressure area will continue the risk for thunderstorm with mostly dry lightning and strong outflow winds on Monday. A Red Flag Warning is out for the highest confidence area consisting of zones 283 and 204 to cover this threat. Thunderstorm formation may also include Northeast Mendocino, Eastern Humboldt, and perhaps far East Del Norte. A shortwave trough will clip N CA on Tuesday, creating a brief southerly wind surge. Terrain funneled and ridgetop winds will be strongest in NE Trinity in the afternoon with gust of 20 to 25 mph for a several hour period, creating locally critical fire weather conditions. There is currently a small chance for additional monsoonal moisture through next weekend. JJW && .EKA WATCHES/WARNINGS/ADVISORIES... CA... Dense Fog Advisory until 9 AM PDT this morning for CAZ101>103-105-106. Red Flag Warning from 11 AM this morning to 9 PM PDT this evening for CAZ204-283. NORTHWEST CALIFORNIA COASTAL WATERS... Dense Fog Advisory until 9 AM PDT this morning for PZZ415- 450. && $$ Visit us at https://www.weather.gov/eureka Follow us on Facebook and Twitter at: https://www.facebook.com/NWSEureka https://www.twitter.com/NWSEureka For forecast zone information see the forecast zone map online: https://www.weather.gov/images/eka/zonemap.png