FXUS66 KEKA 302153 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 253 PM PDT Wed Apr 30 2025 .SYNOPSIS...Warm, dry, and calm weather will persist across the area through Thursday. Light rain and cooler weather this weekend. && .DISCUSSION... KEY MESSAGES: -Hot and dry weather building across the interior through Thursday with highs in the mid 80s. -Regular, shallow diurnal marine layer right along shore, becoming strongest around Friday. -Cooler weather and light rain for the northern half of the area this Wednesday. WEATHER PATTERN OVERVIEW: An upper level ridge has continued to build over the area today. Clear skies and high pressure has allowed for strong warming across the interior with the hottest location reaching near 90 this afternoon. Receding marine influence has even allowed for clear skies along the coast though afternoon sea breeze has kept conditions much cooler. Some cumulus has built up around Lake County though moisture currently seems to low to support any shower development this evening (less than 5% chance). Hot and dry conditions will peak tomorrow before high pressure begins to break around Friday. This will mean interior highs will again peak near 90 Thursday. Winds turning more onshore will also promote a stronger marine layer along shore Thursday and especially Friday. A narrow trough and surface low will skate down the coast early Saturday. At the very least, this low will bring thick cloud cover and much cooler and more moist conditions with highs in the mid 50s. There is potential for wetting rain across the area though any rain will be light. Most likely rainfall for the northern half of the area will be 0.1 to 0.25 inches over 24 hours with just a trace amount of rain further south. The vast majority of model ensemble members show weak ridging and high pressure returning Sunday through mid next week with another trough setting up for later in the week. Gusty north wind will return along shore particularly Sunday afternoon. FORECAST CONFIDENCE AND DEVIATIONS: There is relatively little uncertainty in the overall forecast. In the short term, the greatest uncertainty would likely be associated with the strength of the marine layer on Thursday, though impacts (outside of aviation) will be minimal. In the mid term forecast, precipitation this weekend is the area of greatest uncertainty. The vast majority of models show only very light precipitation with 30% showing even no more than a trace around Humboldt Bay. A very small contingent (10%) shows some potential for rainfall over 0.3 inches along the North Coast. About 20% of models show rain starting late Friday night but essentially all models show rain staring by sunrise on Saturday and then tapering off into the afternoon. /JHW && .AVIATION...Most areas observed SKC today. However, coastal marine stratus developed overnight and was limited to the Humboldt Coast...and extended across numerous cool river valleys. Stratus lingered just along the ACV airport coast til around noonday, with Cig/Vis dipping into IFR during the latter morning. The tight pressure gradient began to cause winds to rev up at CEC around 9 AM (16z). Coastal winds elsewhere were mild-breezy. HREF and other model guidances indicated that the stratus layer would return to the coast overnight/early Thursday morning as winds diminish overnight. Stratus will likely be more widespread, bringing MVFR to IFR conditions to both coastal terminals. /TA && .MARINE...Northerly winds continue across the waters this afternoon. Tonight and Thursday winds start to diminish as an upper level system starts to move into the area. Thursday night into Friday these winds continue to diminish and may briefly go southerly. Waves will mainly diminish with these winds, However there is some a small southerly swell. currently it is around 3 feet at 15 seconds. There is also a northwest swell of 3 to 4 feet at 10 seconds. Friday night high pressure builds in quickly behind the front boundary and northerly winds quickly increase again. There is still some uncertainty on exactly what time these winds will increase, but it will likely be either Friday evening or overnight. Gale force gusts are expected by Saturday afternoon in the southern waters with widespread gales by Sunday morning. Models are in pretty good agreement on a period of 35 to 40 kt winds. Monday winds are expected to diminish slightly, but gale force gusts are expected to linger. Winds will continue to diminish on Tuesday and Wednesday. MKK && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 11 AM PDT Thursday for PZZ450- 455. Small Craft Advisory until 9 PM PDT Thursday for PZZ470. Small Craft Advisory until 4 AM PDT Friday 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