


Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
023 FXUS66 KEKA 022154 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 254 PM PDT Wed Jul 2 2025 .SYNOPSIS...Cooler interior temperatures and a deeper marine layer are expected Thursday and Friday. Temperatures will then trend warmer through the weekend and into early next week. && .DISCUSSION... Satellite imagery and web cameras showed cumulus clouds building over NE Trinity this afternoon. Latest CAMS (convective allowing models) and probabilistic guidance (HREF, SREF and NBM) continue to trend lower with thunderstorms today over NE Trinity and Yolla Bolly`s. All of the CAMS indicate activity on the outside periphery of Trinty and NE Mendo/northern Lake late today. Model based soundings continue to depict steep lapse rates with sufficient CAPE for storms. 500mb ridge building in from the SW and drier westerly flow will most likely cap off storms for our area today. There is still a 1 in 10 chance for lightning over the highest terrain in NE Trinity. For coastal areas, stratus has been slow to clear out and much more extensive than both the NBM and HREF guidance indicates. Statistical guidance and BUFKIT time- height humidity sections more closely resembled current cloudy conditions along most of the coast. A stronger and higher marine inversion will likely keep cool and humid marine air trapped against the coastal terrain tonight into Thursday, especially around Humboldt Bay and Eel delta. A series of upper trough will move across the area Thursday through this weekend. The first one on Thursday will have a strong SW speed max proceeding the trough axis. Isolated showers are possible (20% or less) over high terrain of NE Trinity. It is not completely impossible, 1 in 10 chance, for some cloud-to-ground strikes with trough axis passage Thu evening over NE Trinity or nearby along the borders. A second short wave trough will swoop across the area this weekend and should develop into a semi-closed low over the area bu Sunday. How exactly this trough evolves remains uncertain. Convective parameters are not all that high and there is no compelling reason to depart from the NBM output at this time. Otherwise, interior temperatures are forecast to trend down Thursday through Friday in response to gustier westerly and northwest winds and marine air intruding inland. Temps should warm up over the weekend and continue on an upward trend early to mid next week. Coastal areas will most likely continue to have low cloud cover for the next several days with a deeper marine layer, hopefully clearing out in afternoon. && .AVIATION... Deep marine layer continues to blanket the north coast this afternoon. Greatest chance for MVFR scattering in CEC late this afternoon as northerly winds increase offshore. Gusts approaching 20 knots possible at both coastal terminals and UKI beginning prior to 00Z. HREF shows >80% probability for <1K ft ceilings redeveloping at ACV after 04Z; CEC seems to be slightly underdone and will likely return to IFR ceilings overnight. A weak shortwave will disrupt the wind pattern, bringing scattered high cloud cover and a greater chance for coastal clearing Thursday afternoon (20-50% chance of low cloud cover by 22Z Thursday). Gusty northwest winds 20 to 30 knots possible in UKI Thursday afternoon. && .MARINE... Northerly winds will continue in the outer waters with gale force gusts persisting downwind of Cape Mendocino through late tonight. Steep and hazardous waves will propagate into the inner waters through Thursday, diminishing first in the northern waters as winds gradually decrease. Moderate to fresh breezes will continue in the outer waters through Friday as a long period southwesterly swell fills into the waters, with locally stronger gusts nearshore and downwind of the Cape. Northerlies expected to strengthen again late this weekend as high pressure builds back into the region. NBM currently noting 40 to 50% chance of gale gusts in the outer waters Sunday through Monday. && .FIRE WEATHER... Gusty winds with low daytime RH`s are forecast for portions of zone 283 (Trinity County) and zone 264 (southern Lake County) Thursday afternoon and evening. Wind directions will generally be from the west and northwest and funneled through the valleys. Hold over fires from our recent lightning outbreak may rapidly spread, particularly in Trinity County where lightning activity was most abundant. These enhanced diurnal winds may continue on Friday, but are not forecast to be as strong. The upper trough may also generate some light showers in NE Trinity County and perhaps isolated lightning strikes (a 10% chance) over the highest terrain in NE Trinity. Another trough will follow over the weekend and will pose a low risk for elevated high based and low precipitation producing thunderstorms over the interior, primarily Trinity County. Otherwise, temperatures will warm up over the weekend. The warming will most likely (80% chance) continue all of next week. The magnitude and rate of the warming remains uncertain, but 100F degree heat will be possible. && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 11 PM PDT this evening for PZZ450. Hazardous Seas Warning until 11 PM PDT this evening for PZZ455. Small Craft Advisory until 9 AM PDT Thursday for PZZ470. Gale Warning until 11 PM PDT this evening for PZZ475. && $$ NOTE: The full forecast discussion is now regularly issued between 10 am/pm and 1 pm/am. Additional updates will be issued as needed. 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