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Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
287 FXUS66 KEKA 052214 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 314 PM PDT Fri Jul 5 2024 .SYNOPSIS...Extreme heat will peak on Saturday as high pressure centers directly over NorCal. Enhanced fire weather risk continues with westerly diurnal winds, especially in trinity and Lake counties. Temperatures will ease slightly but remain above average through early next week. && .DISCUSSION...Daytime interior highs climbing into the 100`s again today, likely topping out a few degrees higher than yesterday. Areas already experiencing Excessive Heat Warnings - including valleys of interior Mendocino, Trinity, and Lake counties - are exhibiting high probabilities of highs exceeding 105 this afternoon. Additional temperature records likely to be broken, especially after being compounded with several days of heat. Gusty diurnally driven winds enhanced by strong surface heating/low level instability will increase risk of fire weather in portions of southeastern Lake County through Saturday. With the high pressure ridge moving directly overhead, temperatures will surge even higher on Saturday to meet Major and Extreme HeatRisk criteria in many interior portions of the CWA. Aforementioned interior valleys still showing a 60% chance of exceeding 108-110 degrees by 3 PM. With offshore flow overnight, unusually high temperatures will surge toward the southern Humboldt/Mendocino coast to bring highs into the mid 80`s, 70`s further north. Lower probabilities for coastal highs reaching into the 80`s. As afternoon temps heat up, westerly flow is anticipated to increase across Trinity, Lake and eastern Del Norte counties. With gusts up to 20-25 mph possible, the Red Flag Warning will continue in SE Lake while a Fire Weather Watch begins for Trinity Saturday afternoon. Critically low RH`s in the single digits and teens will exacerbate these conditions. Despite the heat, a mild surge of marine moisture will begin to slowly make its way inland as the westerly flow increases late this weekend. The marine layer will still be fairly week, but overnight RH recoveries are expected to improve to exceed 50% for Humboldt, Del Norte and Mendocino counties. && .AVIATION...ACV/CEC...The coastal terminals are in solid VFR conditions this afternoon. Under the dry airmass and strong subsidence, the stratus has greatly struggled to become better organized off the Mendocino coast. High resolution Models have been overdoing the stratus over the past couple of nights, but there is a higher probability of shallow stratus tonight. MOS guidance is more aligned with at least a brief period of shallow, ground fog formation for early Saturday morning, and the synoptic setup favors that solution if stratus does not fill in. IFR to LIFR conditions would develop with these scenarios, but confidence is low to moderate (57%). Haze and a thin smoke layer from the Shelly Fires in Siskiyou County became trapped under the low level inversion last night, and that should redevelop tonight with minor VIS reduction. UKI....Firmly in VFR criteria. The occasional gusts this afternoon will subside and transition to calm winds. VFR is expected through this 18Z TAF period. && .MARINE...Fair seas and calm winds prevail for all area waters for the next 36 hours or so. Northwesterly winds start to build Saturday night with seas responding by Sunday morning in the northern outer waters as wind waves with square profiles develop. Small craft advisory conditions will begin in the northern outer waters Sunday morning with the previously mentioned square wind waves which will expand into the southern outer waters by Sunday afternoon. Aside from the standout spots around Cape Mendocino and Point St George, the northerly winds of around 20 kts will be confined to the outer water through the weekend, with lighter nearshore winds. /EYS && .FIRE WEATHER...Hot temperatures continue and are expected to bring RH down to 5 to 15 percent this afternoon. The typical diurnal afternoon winds will be slightly enhanced by the hot temperatures and this will increase fire weather conditions. Tonight the valleys are expected to decouple again and see recoveries of 40 to 50 percent. The thermal belts are expected to see temperatures only drop to around 80 with RH recoveries around 20 to 30 percent. This will increase fire danger slightly. Saturday afternoon northwest winds will increase again, especially in southern Lake county. The red flag warning looks on track in southern Lake county. Farther north in Trinity County low RHs and breezy afternoon winds will enhance fire weather conditions - a Fire Weather Watch will go into effect in the afternoon. Sunday as the upper level ridge starts to push east areas closer to the coast are expected to start seeing a slight marine push. Winds are expected to weaken in Lake county, but may remain elevated in Trinity county. Monday there is still the potential for some showers and thunderstorms in the afternoon. This will need to be watched as it gets closer. For now the chance looks less than ten percent. /MKK && .EKA WATCHES/WARNINGS/ADVISORIES... CA... Heat Advisory until 8 PM PDT Monday for CAZ102-112. Heat Advisory until 11 PM PDT Saturday for CAZ104. Excessive Heat Warning until 7 PM PDT Monday for CAZ105-107- 108. Fire Weather Watch from Saturday afternoon through Sunday evening for CAZ283. Excessive Heat Warning until 8 PM PDT Saturday for CAZ106. Excessive Heat Warning until 8 PM PDT Monday for CAZ110-111- 113>115. Red Flag Warning until 11 PM PDT Saturday for CAZ264. NORTHWEST CALIFORNIA COASTAL WATERS... None. && $$ 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