Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
345 FXUS66 KEKA 231122 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 422 AM PDT Mon Sep 23 2024 .SYNOPSIS...Key messages include climatologically warm temperatures for today and Tuesday, with a return to cooler and more typical temperatures for this time of year for Wednesday with drizzle along the coast (mainly Del Norte/Humboldt Counties). Also wind speeds and gusts will be on the higher side, climatologically toward Del Norte County as well as over the waters (especially north). && .DISCUSSION...Overall synoptic pattern continues with an anomalously amplified upper ridge dominating the area, with the axis crossing the area by tonight, allowing for a bit cooler temps for Tuesday, and considerably cooler Wednesday as an upper trough moves in, combining with a closed low off of southern California. Ensemble data reveals that the biggest climatological anomaly for surface temperatures will be over the coast (although some interior valleys could hit toasty temps above 100 degrees). Along the coast in Crescent City, there is a 50 percent chance of high temperatures between 70 and 74 degrees, with the NBM deterministic solution coming in at 68 degrees (average high is 64 degrees). With a calibrated probability of 90% chance of 68 degrees or more at KCEC, it would be a safe bet to bump this up to lower 70s, with a 75% chance of 70 or more. At Arcata, there is a 60% chance of at least 74 degrees for a high temperature. However, we are not anticipating a record breaking event (record is 82), as we stand a 0% chance of 77 degrees or more, according to NBM, as NBM also indicates that offshore flow will generally be not particularly strong and onshore breezes are advertised to kick in by late morning or early afternoon. Also wind speeds toward Del Norte County will be relatively strong, thanks mostly to an increased surface pressure gradient. Little spread in solutions reveal that confidence is high for wind gusts. Mean max wind speeds and gusts are 17 and 30 mph respectively. To get closer to the wind/wind gust solutions suggested by calibrated probabilities in the short term, HiRESWarw was used in conjunction with the mean NBM solution for period 1 afternoon winds/wind gusts over the land with wind gust multipliers near 1.55 this afternoon, giving Crescent City wind gusts pushing 30 mph from the northwest this afternoon. With the incoming upper trough, NBM indicates coastal stratus/drizzle returning Wednesday (mainly Del Norte and Humboldt Counties), with a near 100% chance of sky cover over Crescent City by around 2PM Wednesday, with a 50 percent chance of accumulating drizzle at some point in the afternoon or evening. There will also be a near 100% chance of cloudy conditions occurring with about a 20 percent chance of accumulating drizzle in Arcata (ACV), but this drops off to the south. /MH && .AVIATION...Clear skies are forecast to continue at all terminals through much of this TAF period. Stratus and fog will continue to result in LIFR cigs and vsbys along parts of the Mendocino coast through Monday. Only patchy stratus and fog is expected around Humboldt Bay/Eel Delta with less than a 20% chance for LIFR at KACV from 14Z to 18Z today. Update coming by 12Z. DB/MH && .MARINE...Near gale conditions with occasional gusts to around 35 kt and large steep northerly wind waves near 10 feet are forecast to continue in the outer waters through today. Steep wind waves will also propagate into the inner waters today, primarily in the northern inners. Northerly conditions will ease tonight and then lay down more substantially on Tuesday and Wednesday as the thermal trough weakens and shifts inland. A series of mid period NW swell will build early next week, peaking around to around 8 ft on Wed. Potential for gale force northerlies and large steep waves over 10 feet will increase Fri-Sat. DB && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 9 AM PDT this morning for PZZ450- 455. Small Craft Advisory until 9 AM PDT Tuesday for PZZ470. Small Craft Advisory until 3 AM PDT Tuesday 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