Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
025 FXUS66 KEKA 141133 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 433 AM PDT Fri Jun 14 2024 .SYNOPSIS...Dry weather is expected through the weekend. Interior temperatures continue to trend down today, and are forecast to drop below seasonal normals this weekend. Much stronger westerly to northwesterly winds are expected this afternoon and Sunday afternoon. && .DISCUSSION...Diurnal coastal stratus continues along the Redwood coast this morning as persistent northerlies pool moisture between Cape Mendocino and Crescent City. These low clouds are expected to mix out by late morning due to a mix of daytime heating and the arrival of a weak, dry cold front, which should subtly disrupt the marine layer today. More expansive stratus and fog should redevelop late this afternoon and this evening in the wake of this feature. Further inland, this passing weak front will aid in continuing a cooling trend, with afternoon highs forecasted to drop another 5 to 10 degrees below Thursday`s highs, bringing most interior valleys within a few degrees of climatological normal. Meanwhile, slight building high pressure behind the surface front is expected to enhance the diurnal NW winds this afternoon, with peak gusts likely reaching between 25 and 35 mph this afternoon in southern Mendocino and Lake county, as well as in the Trinity River Valley east of Burnt Ranch. Winds should then weaken tonight at lower elevations as the valleys decouple, while gusts are forecast to continue on ridges in these areas into early Saturday. Afternoon high temperatures continue to fall this weekend as a longwave trough moves over the PNW. A few weak shortwaves move through this feature this weekend and early next week, the most potent of these is forecast to drift onshore Sunday afternoon. The primary concern with this feature once again looks to be wind, and gusts from 25 to 35 mph are once again probable, with lower probabilities for gusts to 40-50 mph in the mountains around Cobb and Cow Mtn. With afternoon RH values forecast to reach the low 20 to teens each afternoon this weekend, there exists a slight risk for rapid spread of grass fires both Friday and Sunday. See Fire Wx section for more details. Otherwise, Slightly cooler air and continued dry conditions with clear skies should result in chilly overnight temperatures once winds decouple. There is a chance (20-40%) for brief morning frost in the colder valleys of Trinity and eastern Humboldt counties this weekend and early next week. There is also a slight chance (10%-20%) that Sunday`s shortwave brings some very light rain to NWRN CA Sunday evening, most likely in Del Norte and northern Humboldt. The latest suite has increased the probabilities of wetting rain, with NBM probabilities for greater than 0.10in now at 20% for Del Norte and northern Humboldt counties, while northern Mendocino sees a 5% chance of a hundredth of an inch. && .AVIATION...Marine stratus will continue to affect the Humboldt and Del Norte coast terminals into mid morning. MVFR to IFR ceilings are expected for CEC and ACV. By late morning, gusty north to north- westerly winds will pick up and raise ceilings and begin to scatter the stratus. Gusty north winds will also affect interior terminals such as Ukiah into tomorrow afternoon. Stratus is expected to return into tomorrow night for the coastal terminals. && .MARINE...Gale force winds gusting up to 40 knots continue in the Southern inner and outer waters through the weekend. The sea state remains hazardous with 10 to 13 ft waves at 8 to 10 seconds. Steep square waves will persist but diminish in wave height, particularly in the northern outer waters. South of Cape Mendocino, gales force gusts will continue with the expansion fan through today. The expansion fan drifts more into the southern inner waters through today, which could lead to the return of gales near-shore, but these will subside below gales by this evening. Gales in the southern outer waters will pause this evening and return by Saturday afternoon. The sea state will continue to be characterized by northerly wind waves and mid-period northwesterly swells through the weekend. /JB /EYS && .FIRE WEATHER...Enhanced west to northwest winds are expected to develop this afternoon, weaken Saturday, and then strengthen once again Sunday afternoon. Gusts will likely range from 25 to 35 mph across southern Mendocino, southern Lake, and in the Trinity River valley east of Burnt Ranch both Friday and Sunday afternoon. Winds are expected to be stronger Sunday, with better chances of more frequent gusts, and potential for gusts to reach above 40 mph at higher elevations. Dry conditions with low daytime RH`s in the 20`s and teens are expected to continue through the foreseeable future, primarily in Lake and Trinity counties, and interior Mendocino. RH recoveries are expected to increase slightly on Monday morning as moisture associated with the passing shortwave moves in. The strong winds and low humidity will yield an elevated fire weather threat Sunday, particularly for the south and east side of Lake County. Have to opted to continue the Fire Weather Watch in zone 264 (southern Lake), and cover the threat this afternoon with headlines. && .EKA WATCHES/WARNINGS/ADVISORIES... CA... Fire Weather Watch from late Saturday night through Monday afternoon for CAZ264. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 3 PM PDT this afternoon for PZZ450-470. Small Craft Advisory until noon PDT today for PZZ455. Gale Warning from noon today to 9 PM PDT this evening for PZZ455. Gale Warning until 3 PM PDT this afternoon for PZZ475. && $$ 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