Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
861 FXUS66 KEKA 210723 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 1223 AM PDT Fri Aug 21 2026 .KEY MESSAGES... * Smoke remains stuck around the Hoopa Valley with weak mixing keeping smoke stuck in terrain into the weekend. * Very slight chance for isolated dry storms in the interior during the day Friday. * A deep marine layer and cooler temperatures aloft will combine to bring near to slightly below normal temperatures Friday and Saturday. && .SYNOPSIS...A deep marine layer and cooler temperatures aloft will combine to bring near to slightly below normal temperatures Friday and Saturday. The coast may finally see more clearing over the weekend. Some warming is expected Sunday and Monday before another trough brings cooler temperatures next week. && .DISCUSSION...An upper level low is approaching the coast and then moves north along the coast. This is pulling sub-tropical moisture north over the area. This is showing up in the sounding at Oakland with a PWAT of 1.08 inches. No CAPE was recorded with this sounding. The upstream satellite imagery doesn`t look convective and doesn`t have lightning reported with it. So there is still the potential for some lightning, but it is not looking very likely. Temperatures are expected to diminish this afternoon as the marine layer continues to deepen and get pushed further inland. Many of the inland areas are expected only warm to the upper 80s or around 90. The marine layer looks like it will keep the marine clouds in place the immediate coast. With the deeper marine layer this should keep ceilings a bit higher and limited fog in the lower elevations. Saturday the upper level low starts to move out of the area with high pressure filling in behind it. This will bring cooler temperatures aloft which will keep the inland areas mainly in the 80s with 70s closer to the coast. The may finally see some better clear and breezy afternoons winds. The cooler temperatures aloft will weaken the marine inversion. Saturday night into Sunday morning there is some offshore flow and this may help clear skies out more quickly during the day. It doesn`t look strong enough to keep skies clear overnight. Monday through the middle of the week a trough starts to approach the area bringing a cooler temperatures and deeper marine layer again. This is come more from the west and thunderstorms look unlikely, but it will be something to watch as it gets closer. MKK && .AVIATION (06Z TAFS)...The approaching upper level low is deepening the marine layer. This is keeping CIGS higher at the coastal airports. Farther south the marine layer has deepened in Mendocino as well and has the potential to make it into Ukiah. However the winds are out of the north currently in Ukiah. There are southerly winds in Sonoma county so it looks like it will be a battle between the winds. This will likely keep stratus out of Ukiah, but possibly up into Hopland. This afternoon the marine clouds are expected to lift some and CIGs are expected to become MVFR by the afternoon. Tonight the probability of CIGS dropping below 1,000 feet again is 50 to 70 percent while below 2,000 feet has a more than 90 percent probability so CIGS tonight may remain MVFR. MKK && .MARINE...The winds and seas continue to diminish and are expected remain fairly light through much of the day. The winds are expected to be southerly in most areas, but only around 4 to 8 kt. Low clouds are expected, but generally fog is not expected. Currently there is a westerly swell around 3 feet at 11 seconds and the wind driven waves have diminished along with the winds. Saturday northerly winds are expected to start increasing again in the southern waters to around 15 to 20 kt, strongest just south of Cape Mendocino. Saturday night into Sunday winds are expected to continue to increase, peaking around 15 to 25 kt in the afternoon. The northerly winds are expected to start to diminish once again Monday and Tuesday. There is the potential for them to start increasing once again on Wednesday. MKK && .FIRE WEATHER...Hot and dry weather conditions to ease Friday, especially with the help of upper level clouds. Highs will pull back closer to the 90s with RH over 20 percent. There is still a small chance for lighting through the day Friday, but none of the models are predicting lighting. One or two models still show a little instability and there is still a jet streak that could help with the dynamics. But overall it still looks unlikely and if anything forms it would like only be a strike or two. 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. 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