Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
847 FXUS66 KEKA 251154 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 454 AM PDT Wed Sep 25 2024 .SYNOPSIS...Cooler temperatures are expected today, with warmer drier conditions returning by the end of the week and well into the weekend. Coastal low clouds and fog are intruding into low lying areas already this morning. This could hinder visibility during the morning commute. Strengthening northerlies and clearer skies are expected at the end of the week. && .DISCUSSION...A band of moisture approaches the area as a shortwave trough ushers in a cooler trend, albeit short lived. The expected amount of precipitation has dwindled to just a few tenths, mainly for northern Del Norte. Most of the moisture will be represented by stratus which has already made its` way up the Eel River this morning. There is also a dense lobe of stratus and fog advecting from the south, up the Russian River valley and into southern Mendocino, reaching Yorkville and Hopland as of 12z. Area profilers for Bodega Bay are showing moisture depth to be around 2000ft with additional intrusions coming from the coast, already reaching Comptche. Limited visibility during the morning commute is a possibility as dense fog is likely, especially after a couple days of offshore flow pushing warm air out over the chilly coastal waters. Ensemble means and deterministic guidance continues to indicate above normal 500mb heights and above normal 850mb temperatures returning toward the latter portion of the week and this weekend. Above normal interior temperature will most likely return Friday and over the weekend as northerlies increase offshore over the coastal waters, eventually becoming northeasterly over land areas with the development of a thermal trough. Looking at the National Blend of models (NBM), sure enough chance for 95F in the interior valleys increase to over 50% as early as Friday. Moderate heat risk is forecast to continue over the weekend into early next week with above normal interior warmth. Coastal warmth with highs around 70F or more will also be possible (25-35% chance) Fri and Sat, though deep column easterlies will be missing in this offshore case. Significant rain (a tenth of an inch) remains highly unlikely for the next 7 days. /DB /EYS && .AVIATION...A shallow but expansive layer of fog and stratus has blanketed the coast this morning, bringing LIFR conditions. The layer has struggled to move inland at all with satellite data showing stratus no further inland than Fortuna. Most models show inconsistent LIFR to IFR conditions continuing through most of the day. A passing shortwave overhead is likely providing just enough lift to pull the bank of clouds inland, but the weak autumn sun and weak winds today will provide no opportunity to mix the marine layer out. Some brief windows of VFR are likely (50% chance) this afternoon as stratus oscillates along shore, but exact timing and duration of any clearing is highly uncertain. Low clouds will most likely persist tonight with improved clearing on Thursday. /JHW && .MARINE...Only very weak to gentle northerly winds have been observed this morning. That said, a moderate, mid period northwest swell up to 9 feet at 14 seconds has prevented the sea state from being totally calm. This swell will continue to dominate the sea state today as winds remain mostly calm. Northerly winds will begin to rebuild Thursday afternoon first in the southern waters with moderate breezes gusting up to 26 kts. Winds will continue to increase and spread north by Friday. There is uncertainty as to the exact strength of winds, but model ensembles generally show around a 30 to 50% chance of gusts reaching gale force Friday into the weekend. Regardless of exact strength, steep short period seas over 8 feet should be expected, especially in the outer waters and fanning south of both Cape Mendocino and Pt. St. George. /JHW && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory from 3 AM Thursday to 9 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