Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
103 FXUS66 KEKA 202248 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 348 PM PDT Fri Sep 20 2024 .SYNOPSIS...Dry and warming trend is expected this weekend, with interior hot temperatures early next week. Breezy north- northwesterly winds along the coast through this evening, with gusty offshore flow over the interior ridges into Saturday morning. && .DISCUSSION...High pressure offshore will continue to build over the West Coast during the next 24 hours. Pics from the sky depict mostly sunny across the forecast area, with the exception of lingering stratus along the Mendocino Coast. Breezy north- northwest have developed this afternoon with a thermal trough near the coast. Gust from 30 to 40 mph are already observed over the coastal headlands north of Cape Mendocino. North-northwest winds are expected to diminish this evening. Meanwhile, offshore flow continue developing this afternoon and increase later this evening over the exposed ridges, especially in Del Norte, Northeastern Humboldt and Lake County where gusts from 25 to 35 mph are likely. This drier offshore airmass will promote low humidity across the area. See Fire Weather Section for more details. Offshore winds will yield clear skies along much the coast late tonight and through the weekend. The ridge will slowly amplify this weekend with a 850 mb temperatures warming through early next week. Temperatures will peak early next week when the warmer inland valley temperatures reach into the upper 90s into 100. These temperatures will be 10 to up to nearly 15 degrees above normal and will bring areas of Moderate Heat Risk Monday and Tuesday. Ensembles and deterministic models suggest the upper level ridge shifting eastward on Tuesday as an upper level trough approaches from northwest, while, a surface cyclonic circulation approaches from south along the coast. This surface low will bring a southerly reversal stratus surge Tuesday evening into Wednesday morning, with low clouds and patchy fog charging up and lapping the coastal areas. This will bring a push of marine air to the interior on Wednesday. Some cooling is expected on Wednesday, but high temps will remain above normal through the end of the week. && .AVIATION...Elevated winds from the N to NE are creating notable low level wind shear today. These winds will increase tonight with 30 to 35 kt winds down to 1500 to 2000 ft AGL. This threat will linger longer in Del Norte County Saturday where NE winds aloft will be stronger. The shallow stratus has scattered out this afternoon. The increased northerly winds this afternoon followed by a descent nocturnal offshore push will greatly limit stratus formation. NBM is maintaining an around 40% chance for a return of LIFR CIGS tonight around Humboldt Bay and into ACV. HREF holds lower chances, around 20%. VFR conditions are anticipated elsewhere. && .MARINE...Gale strength northerlies with gusts up to 40 kts have developed over the waters. These winds have the highest coverage over the outer waters, but gale conditions will intrude the inners around Cape Mendocino and Point St George. In response to the winds, seas will continue to build to 14 ft at 10 seconds by this evening. These very steep and hazardous seas will propagate into the inner zones this evening and into midday Saturday. A Hazardous Seas Warning is out for the Northern Inner zone 450. Winds and seas will be very slow to subside on Saturday. && .FIRE WEATHER...Breezy offshore flow will continue to developed and increase over the higher terrain in Del Norte, northeastern Humboldt and eastern Lake counties this afternoon and evening. Low daytime humidity with values from 15 to 25 percent are occurring across the interior this afternoon. Drier offshore airmass will promote poor RH overnight recoveries on Saturday morning. Elevated to locally critical conditions are expected tonight into Saturday due to gusty northeasterly winds and poor RH recoveries over the higher terrain in zones 203, 204, and 264. Winds are expected to diminish later Saturday morning. Winds will shift to west-northwest across the southern portion of the area Saturday afternoon. Temperatures in the upper 90`s into 100, low humidity and gusty offshore winds will promote critical fire weather conditions Monday and Tuesday. && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 9 PM PDT this evening for PZZ450. Hazardous Seas Warning from 9 PM this evening to 9 AM PDT Saturday for PZZ450. Small Craft Advisory until 9 AM PDT Saturday for PZZ455. Gale Warning until 9 AM PDT Saturday for PZZ470-475. && $$ 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