Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
765 FXUS66 KEKA 261153 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 453 AM PDT Wed Jun 26 2024 .SYNOPSIS...An upper level disturbance and associated surface front will produce widespread marine stratus and relatively cooler temperatures through Thursday. Warming trend returns for this weekend into next week. && .DISCUSSION...Last few remaining showers in eastern Trinity county are exiting the region after a mildly unstable day. Widespread marine stratus once again inundating the NorCal coast with <1000 foot ceilings, reduced viz and drizzle amidst light southerly flow. HREF indicating these conditions will persist through the morning as moist onshore flow advects low fog and mist further inland and into coastal river valleys. Accumulations of a few hundredths of an inch of precip on the Redwood Coast are possible by late morning. An upper level trough will steadily converge onto the north coast, providing just enough lift to mix the BL and break up the stratus deck with afternoon diurnal heating. It is unlikely that cloud cover will completely dissipate before a resurgence of moisture along the surface frontal boundary late Wednesday evening. Hi-res models including HREF have been showing potential for light precip on Humboldt and Del Norte coasts by early Thursday morning as this front traverses the region. With this upper trough also comes cooler temperatures across the CWA. Highs only expected reach the mid 70`s to low 80`s across the interior while coastal highs continue to be dampened by marine stratus. NBM anticipating some valleys in southern Mendocino, Lake and eastern Trinity counties to rise into the upper 80`s, although probabilities significantly fall off at 90 degrees. Enhanced NW winds are also expected this evening and overnight, especially in Lake and Trinity counties. Wind gusts 15-25 mph are possible alongside 20-35% RHs before recovering to 50-60% overnight. A similar pattern is expected Thursday as stratus struggles to clear beneath a marine inversion. Similarly cool temperatures and diurnally driven NW flow expected with the lowest RHs remaining in eastern counties bordering the Sac Valley. Coastal winds may increase in the afternoon as the thermal trough redevelops beneath building high pressure. Broad, weak ridging is expected to continue late this week with slightly warmer temperatures. Additional upper shortwaves will provide similar disturbances this weekend before potentially for a more substantial return to warm and dry conditions early next week. && .AVIATION...IFR/LIFR conditions with OVC layer between FL003-FL015 with visibility in mist at the coastal terminals early this morning, with a deeper marine layer along the Redwood Coast. The McKinleyville profiler indicates a marine layer depth up to around 2,500 feel MSL. Patchy drizzle has been occurring along the North Coast as result of this uniform saturated layer. Otherwise, stratus are expected to gradually lift and scatter out during the morning and early afternoon as an approaching shortwave destabilize the marine layer. Expect fluctuations in conditions at the coastal terminals after 19Z, mainly between MVFR and VFR. Meanwhile, VFR conditions prevail at UKI. Winds will remain fairly light this morning, becoming WNW at 5-10 kt late morning/early afternoon at ACV and CEC....while up to 15 kt at UKI, with occasional gusts up to around 20 kt from 26/21Z and 27/3Z. && .MARINE...Weaker winds across the coastal waters this morning. Moderate to locally fresh west to northwest breezes are expected to south of Cape Mendocino this afternoon. Seas are dominated by a decaying northwest swell. Northerlies will increase and spread from south to north across the coastal waters Thursday into Friday, with the strongest winds across the outer waters. Wind driven seas are expected become steep and hazardous for small craft as result. Near gale to locally gale force gusts is possible across the outer waters on Friday, generating steep seas, with short period seas picking up to around 8 to 10 feet at 8 to 9 seconds Friday afternoon. Winds diminish throughout the weekend as another upper level trough moves over the area. && .FIRE WEATHER...Gusty NW winds combined with 20-30% minimum daytime RH values may pose an increased fire weather threat this afternoon and evening, especially in Lake County. Greatest threat to fine fuels in areas below 2000 feet. && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. 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