Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
123 FXUS66 KEKA 262222 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 322 PM PDT Fri Apr 26 2024 .SYNOPSIS...Cooler temperatures and drier weather are expected tonight after a few lingering evening showers. Chance for light rain will return by midday Saturday, followed by drier weather and below temperatures Sunday into early next week. && .DISCUSSION...Shower activity has been steadily diminishing this afternoon as an unseasonably cold upper trough progressed into the Great Basin. Robust NW flow aloft on the backside of the trough will diminish tonight as a ridge builds aloft, stability increases and deep mixing subsides. Shallow moist air will likely result low cloud cover and perhaps fog in the interior valleys tonight. Precipitation totals over the last 24 to 36 hours varied widely. For interior Del Norte, 1.72-2.19 occurred, while southern Mendocino (Ukiah) and southern Lake received no measurable rain. Blustery W-NW winds will persist across southern Lake and southern Mendocino into this evening with peak gusts from 20 to 40 mph, highest over the exposed ridges and channeled terrain of Lake County. Another frontal system with a long westerly fetch of high PWATS (125-150% of normal) will approach on Saturday. Some light rain may occur (30-50% chance for a few hundredths) primarily north of Cape Mendocino. Amounts most likely will not exceed a tenth in 6 hours though a HREF has 60% chance over the higher elevations of Del Norte and Humboldt. A few hundredths appear more probable (60% chance). Subfreezing temperatures are highly probable (80% chance) for the mountains above 3000-3500 feet tonight and Saturday morning. Probabilities for valleys to freeze are much less certain with only a 20-40% chance for the typical cold valleys in Trinity, eastern Humboldt and NE Mendocino. Fog and low clouds will form in the valleys and hinder the longwave cooling. Otherwise, broad and flat ridging is forecast to build offshore as a series of shortwave troughs brush the northern portion of the area, mostly Del Norte county, with periodic precipitation chances into mid week. Low-amplitude westerly flow will most likely keep temperatures on the mild side and near seasonal normals through early next week. Greater uncertainty arises mid to late week with potential for flow amplification over the NE Pacific and above normal interior temperatures. DB && .AVIATION...Widespread MVFR/IFR conditions prevailed across the region as another weather disturbance moved through NW California this morning. Marginal flight impacts occurred at coastal airports; this included light to moderate rain and associated mist (fog). Inland locations were mostly VFR, occasionally fluctuating into MVFR in the mid- morning...and little reported rain. More importantly, some locales reported WNW breezy to gusty winds this afternoon. Across the region, model guidances are suggesting general improvement (post frontal) before another "not so dynamic" weather system began to influence the coastal terminals overnight. The result will be deteriorating conditions in late morning into afternoon; this includes low Cig/Vis and rain. /TA && .MARINE...Light to gentle breezes in the northern waters are forecast to continue through the weekend as another weak frontal boundary approaches from the NW. Moderate to fresh NW breezes in the southern waters are expected tonight into Saturday. A small craft advisory remains in effect. As winds subside on Saturday, steep northerly waves are forecast to continue through the day and a small craft advisory remains in effect until 6 PM Saturday. A persistent NW swell at 9 seconds around 7 feet will likely continue into Saturday. A longer period W swell near 15 second around 3 ft will arrive on Saturday. Larger combined seas (8 to 10 ft) are expected to build early next week as northerly winds strengthen, especially south of Cape Mendocino where a few gusts to 35 kt are possible (50% chance). EYS/DB && .EKA WATCHES/WARNINGS/ADVISORIES... CA... Frost Advisory from 2 AM to 8 AM PDT Saturday for CAZ107- 108-110-111-114. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory from 5 PM this afternoon to 6 PM PDT Saturday for PZZ455-475. && $$ 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