Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
638 FXUS66 KEKA 211057 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 357 AM PDT Sat Sep 21 2024 .SYNOPSIS...Warm and dry conditions will continue to gradually settle in today with continued gusty north winds along the coast. Heat will peak early next week with above average temperatures pushing out even along the coast. && .DISCUSSION...High pressure is continuing to build across the eastern Pacific and gradually drift towards shore. Gentle offshore flow overnight coupled with very dry air aloft has allowed for clear skies all around the area. Enhanced nighttime inversion are apparent throughout interior valleys with high elevation lows in the mid 60s compared to valley lows in the upper 40s. The gradually building heat dome will allow temperatures to creep upwards today with hot interior valleys reaching the mid 90s, which is a solid 10 degrees above normal for most locations. Lingering offshore flow this morning may aid in some brief warming near 70 along the coast, especially with clear skies, but gusty north wind right along shore of 10 to 20 mph will generally pull marine influence inland in the afternoon while simultaneously scouring out any marine stratus. High pressure will build and peak early this week with the hottest temperatures most likely Monday and Tuesday. There is a 60 to 80% chance of highs above 100 along the Russian and Trinity River Valleys. In addition, most models are placing a close low off the Central California Coast during this time. This low will encourage offshore wind which which, combined with the high pressure, will help push particularly warm conditions very close to the coast. Thank to this pattern NBM has a 50 to 70% chance of highs over 100 in Garberville and a 30 to 50% chance of highs in the mid 70s around Humboldt Bay. Such above normal temperatures, combined with little overnight relief will help support moderate and very localized major heat risk. None the expected temperature, however, are near record breaking. There is high model agreement that high pressure will weaken by mid next week and give way to a broad and shallow trough across the Pacific Northwest. About 30% of model ensemble member shave the trough dip just south enough to bring light wetting rain right along the North Coast. Essentially no model members show any rain more than a few tenth of an inch. Most model ensemble member show no precipitation beyond coastal drizzle with trough just bringing generally cool temperatures and increased clouds cover, especially with a marine layer along the coast. There is high confidence in a generally benign, dry, and seasonable patten continuing through the end of the week. By next weekend there is wide model disagreement. About 10% of cluster ensembles show a widespread wetting rain event while 20% show the total opposite with a moderate heat wave. The majority (70%) show weak high pressure and generally dry but seasonable conditions. /JHW && .AVIATION...Skies are clear over much of the north coast tonight due to easterly wind aloft. Stratus development has yet to initiate this morning and should remain as such throughout the day leading to VFR conditions. Possible visibility reductions due to haze aloft over the coastal terminals. Wind shear is forecast to be a threat at the KCEC due to strong northerlies at the surface and easterlies aloft at 2000 ft AGL. Tonight, there are low probabilities (~20%) of fog returning to the coastal terminals according to the NBM and HREF models. Inland, KUKI is forecast to remain as VFR conditions with its daily wind patterns. && .MARINE...Gale strength northerlies with gusts up to 40 kts have developed over the waters. These winds have the highest coverage over the outer waters, but gale conditions will intrude the inners around Cape Mendocino and Point St George. In response to the winds, seas will continue to build to 14 ft at 10 seconds by this evening. These very steep and hazardous seas will propagate into the inner zones until midday Saturday. Winds and seas will be very slow to subside on Saturday. && .FIRE WEATHER...Building high pressure has allowed for enhanced thermal belts to form overnight. While protected valleys have continued to see very high RH recovery above 80 percent, midslope and high elevation locations are generally between 30 and 50 percent early this morning. North wind offshore has also enhanced nighttime northeast flow, with isolated gusts of 20 to 30 mph this morning mostly just at the high elevations of the western Klamath Mountains. Building heat and high pressure this weak will continue to enhance fire weather conditions with daytime highs in the mid 90s to low 100s and minimum RH in the teens. Overnight recoveries will continue to worsen at mid and high elevations with recoveries of 20 to 40 percent though Tuesday morning. Daytime winds will continue to be mostly gentle and terrain driven, but low pressure of the central california coast combined with high pressure will help enhance night time northeast flow at high elevations. Northeast wind gusting up to 25 mph should be expected a high elevations late each night early this week. This risk will be focused in the usual areas of Del Norte and Lake Counties but will also include the usually calmer ridges of Southern Humboldt and northern Mendocino Counties. Generally more mild conditions will build in late in the week with increasing marine influence. /JHW && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Hazardous Seas Warning until 9 AM PDT this morning for PZZ450. Small Craft Advisory until 9 AM PDT this morning for PZZ455. Gale Warning until 11 PM PDT this evening for PZZ470. Gale Warning until 9 AM PDT this morning for PZZ475. Hazardous Seas Watch from 9 AM PDT this morning through late tonight 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