Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
423 FXUS66 KEKA 232218 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 318 PM PDT Thu Jul 23 2026 .KEY MESSAGES... * Elevated fire danger Friday in Trinity, Lake and NE Mendocino counties due to low RH and breezy winds. * Near normal inland temperatures expected through next week. * Night and morning coastal clouds with afternoon clearing. && .SYNOPSIS...A persistent upper level trough north of the area will bring near to slightly below inland temperatures and slightly warmer than normal coastal temperatures. Breezy winds are expected each afternoon, especially over the inland areas. This will increase fire danger in Trinity, Lake and NE Mendocino county with low afternoon RH. The coast is expected to continue to see night and morning coastal clouds. && .DISCUSSION...An upper level low off the coast is slowly moving north and is expected to settle into the Pacific Northwest. This is expected to be the main driver of the weather through early next week. This is bringing near or slightly below normal inland high temperatures. At the coast this is bringing unusually warm temperatures with highs in the upper 60s today and low 70s yesterday. These appear to have been caused by southerly winds aloft downsloping and warming the air. These winds aloft look to turn slightly more southwesterly tonight and Friday which could bring temperatures at the coast back closer to normal, but it is uncertain on how quickly this will happen. Winds at the surface are generally expected to some version of westerly bringing in a deeper marine layer and keeping the from dropping very low in the afternoon. Farther inland will see RH in the teens, especially on Friday. For more details see the fire weather section. The marine layer was fairly deep this morning, likely around 2500 feet. THis allowed stratus to spread well inland to areas such as Hyampom. With the cooler temperatures aloft the marine inversion was fairly weak allowing skies to clear out by midday at most of the coast despite how extensive the coverage was. Tonight these clouds are expected to return once again. It still looks like skies will clear fairly well by midday again on on Friday. For the weekend and into early next week conditions are expected to remain fairly persistent with the trough to the north of us and a building ridge south of us. There is some uncertainty on how this will impact the marine layer, but it generally looks like it will remain deep. Most of the times this means the inversion will be weak and it will clear out fairly well each day, however confidence is low and there could be some subtle changes to this. MKK && .AVIATION...The marine layer was fairly deep this morning, likely around 2500 feet. This kept CIGS in the MVFR category for the most part, but also allowed stratus to spread well inland to areas such as Hyampom. With the cooler temperatures aloft the marine inversion was fairly weak allowing skies to clear out by midday at most of the coast despite how extensive the coverage was. Tonight these clouds are expected to return once again. It looks like they will drop to around 1,000 feet. With the deep marine layer it looks like LIFR conditions are less likely and conditions will border on MVFR and IFR. It looks like skies will clear fairly well by midday again on on Friday with the continued weak inversion. MKK && .MARINE...There generally light winds across the waters this afternoon with a split flow pattern. North of Cape Mendocino is seeing light southerly winds while areas farther south are seeing northerly winds. These are all less than around 10 kt. There are several swells moving through the waters as well. There is a southerly swell around 3 feet at 15 seconds, a northwest swell around 2 feet at 9 seconds and then some 1 to 2 foot wind driven waves mainly in the southern waters. The swells are generally expected to remain fairly small. Friday a long period southerly swell is expected to start building in to around 2 feet at 21 seconds. If this comes in larger than expected it could lead to a sneaker wave threat. This general pattern is expected to continue through Saturday. Sunday and into next week northerly winds start to gradually increase, but only to around 10 to 20 kt by early next week. && .Fire Weather...General onshore flow and a trough to the northwest of the area will keep RH higher and temperatures lower. However this trough will also bring some breezy northwest winds to much of the area. Areas farther away from the coast are expected to see lower afternoon RH and moderate recoveries overnight. This is expected to increase fire danger in Trinity, Lake and NE Mendocino counties especially on Friday. These areas are expected to see RH drop in the teens Friday and see wind gusts in the afternoon of 20 to 25 mph. Saturday the afternoon RH is expected to increase slightly with similar winds. This pattern is generally expected to continue into next week with only slight fluctuations on the RH and wind. MKK && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... None. && $$ NOTE: The full forecast discussion is now regularly issued between 10 am/pm and 1 pm/am. Additional updates will be issued as needed. 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