Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
921 FXUS66 KEKA 011300 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 600 AM PDT Sat Jun 1 2024 .SYNOPSIS...Conditions in the northern areas are expected to deteriorate this weekend before a short spurt of wetting rainfalls arrives Sunday night into Monday. Southern areas will cool off but are not expected to experience any meaningful precipitation at this time. Next week, temperatures will soar to well above average from the interior to the coast, possibly reaching over 100F in some places. && .DISCUSSION...A brief weak shortwave moved by overnight. Despite a narrow area of mid to high level cloudiness, moisture was limited. Stratus and patchy fog blanketed much of the Humboldt coastal waters, and expanded well up the adjacent river valleys. The McKinleyville profiler indicates a marine layer depth up to around 2,500 feel MSL. Patchy drizzle may occur with a slightly deepening marine layer in the vicinity of Humboldt Bay this morning. Otherwise, stratus are expected to gradually lift and mix out by late morning. However, expect a partly to mostly cloudy skies as mid to high level clouds spread across the area. Temperatures today will run 5 to around 10 degrees cooler compared with yesterday`s readings across the interior, while seasonal temperatures remains along the coast. Inland highs are forecast to be in the mid 70s to mid 80`s. A last push of gusty northwest winds in Mendocino and Lake counties will occur today as the tightest pressure gradient shifts south over those counties bringing gusts to around 30 mph or locally higher on some ridge tops during the afternoon and evening. Sunday into Monday, models consistently show the track of a late- season low pressure system approaching the Pacific NW. South of that feature, a broad zone of WAA and west-southwesterly moisture flux will aid in light rain or sprinkles over coastal Del Norte Sunday morning. PWAT values are expected to increase to around 1 to 1.5 inches along the California Coast by Sunday afternoon as the frontal system sag into NW California. The 00z ECMWF Extreme Forecast Index (EFI) continues to suggest a high-end event climatologically, with EFI values in excess of 0.7 for most Del Norte County and northern Humboldt. Heaviest rain is forecast to occur late Sunday night into Monday morning in Del Norte and far northern Humboldt, as a west- southwesterly IVT plume intersects the coastal terrain. Rain rates looks to remain below 0.3 in/hr across Del Norte County. NBM probabilities range from 45% to around 60% of an inch or more late Sunday night into Monday morning those two counties. Overall this should only be a beneficial rain. Rain chances will quickly decrease farther south and east into Trinity and Mendocino counties where by the farther south portions of Mendocino and Lake counties may see no rain at all. The front will move through the entire region by Monday evening. Quickly behind this front ridging will build back over the west coast allowing temperatures to rebound quickly into the 90s and even to near or exceeding 100 degrees in Lake County on Wednesday and/or Thursday. With the expanding heat there will also be increasing heat risk in the far southeastern portion of the area, particularly near Clearlake. In coordination with the weather office in Sacramento, we went ahead and issued an excessive heat watch from Tuesday through Thursday to highlight this risk. At this time it`s more likely that only heat advisories will be needed but it isn`t impossible that warning thresholds could be reached when the heat peaks mid week. && .AVIATION...Stratus development has been isolated to the Humboldt coast, south of Orick and down to Capetown. This equates to VFR and light southerly winds at KCEC switching to a westerly prevailing wind before the afternoon. That said, stratus has developed over KACV with ceilings above 1000ft and visibility not being impacted as much. Expect MVFR to last through the morning at KACV with a few periods of IFR if ceilings dip below 1000ft, which is possible by dawn. Light southwesterly winds at KUKI this morning will see a return to gusty northerly winds by the early afternoon with VFR conditions continuing throughout. Low Level Wind Shear, LLWS, at KUKI is probable as winds mix down before the afternoon. /EYS && .MARINE...Gale force gusts have become less frequent in the southern outer waters yet, hazardous seas conditions remain as steep waves continue around 9 - 10 ft and as many seconds in period. Gusts in the low 30`s are still being reported at Point Arena as of 11z (4AM), this morning. Gusty winds and steep waves will subside by the late afternoon and remain isolated to a narrow area south of Cape Mendocino. This weekend, an upper level trough is expected to weaken the winds. Sunday a northwest swell around 10 seconds will be the main wave. Initially it is expected to be around 3 feet, but will build to around 6 feet at 10 seconds by Tuesday. Larger combined wave heights are expected Wednesday, 13 to 15 feet. /EYS && .EKA WATCHES/WARNINGS/ADVISORIES... CA... Excessive Heat Watch from Tuesday morning through Thursday evening for CAZ114-115. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 9 AM PDT this morning for PZZ450. Small Craft Advisory until 3 AM PDT Sunday for PZZ455. Small Craft Advisory until 1 PM PDT this afternoon for PZZ470. Hazardous Seas Warning until 9 AM PDT this morning 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