820 FXUS66 KEKA 201944 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 1244 PM PDT Fri Jun 20 2025 .SYNOPSIS...Stronger west and northwest winds expected to continue for the interior Friday through Saturday. Much cooler with below normal temperatures for the interior Friday and Saturday. Temperatures warm Sunday and remain near seasonal norms next week. KEY MESSAGES: - Elevated to locally critical fire weather conditions through Saturday evening for Lake, eastern Mendocino and eastern Trinity Counties due to low RH`s and stronger northerly winds. - Much cooler Friday and Saturday in the interior, followed by a warming and drying trend early to mid next week. - Light rain possible for Del Norte and northern Humbodlt Friday afternoon and evening with some lingering showers possible Saturday. && .DISCUSSION...Prime concern through Friday evening will be strong, gusty west and northwest winds across the interior. Gusts over 35 mph are being recorded. Higher terrain and ridges have a high probability for gusts over 35 mph (87%) and moderate to high chances for gusts of 40 mph over the standout peaks (57-68%) as an unseasonably cold 500mb low drops down from the Gulf of AK on Friday. Friday looks to be the strongest wind day while humidity generally increases. Portions of Lake, eastern Mendocino and eastern Trinty will likely have low humidity around 20-25% on Friday. With the trough enhancing diurnally westerly and northwesterlies breezes on Friday, elevated to locally critical fire weather conditions are forecast. Risk for small and fast spreading grass or brush fires will increase. Winds may not line up exactly with low RH`s for 8 hours or more for a red flag warning. Winds will lessen some, but remain gusty with 70-80% chance for gusts of 30 mph over the ridges Saturday afternoon and evening. We will message this fire weather threat in weather story graphic and social posts. The radar is showing some light showers from the arrival of the trough/surface front. Light showers are still forecast for mainly Del Norte County this afternoon and tonight, with a second burst of showers possible again Saturday with wraparound moisture on the backside of the trough. There is a slight chance for a stray thunderstorm to form mainly over interior Del Norte County this afternoon and evening. Soundings do not look impressive for this scenario, but SPC mesoanalysis show sufficient amounts of MUCAPE this afternoon and lapse rates will be steepening. Clearing skies and lessening winds in the valleys will allow for temperatures to drop to chilly levels in the interior under this colder and drier airmass. A Frost Advisory has been hoisted for some colder interior valleys. Areas where cloud cover lingers and winds stay up will not likely reach frost criteria. A warming trend is forecast early to mid next week with highs in the lower to mid 90`s by Wed for the interior valleys. Also of note is the possibility (currently 5% chance or less) for thunderstorms over the interior mountains Monday afternoon as troughing and additional shortwave energy remains over the region. Moisture looks very limited at this time, but there is variability in model scenarios. && .AVIATION...(18Z TAFs) A cold front entering the PacNW is changing our normal weather conditions. Inland terminals can expected increased elevated winds aloft with gusty NW surface winds. Inland winds are expected to remain elevated through the night. Along the Humbodlt and Del Norte coast, winds will be lighter and possible MVFR conditions are expected late this afternoon through this evening due to rain showers migrating over terminal spaces. Along the Mendocino coast, winds will be stronger with NW gusts up to 25kts, scattered cloud coverage, and no rain expected. Confidence: Forecast confidence is high with inland terminals having breezier than normal winds. The top of the mixed layer shows gusts up to 26kts at KUKI, these winds are expected to reach the terminals. Winds overnight will remain elevated due to synoptic forcing instead of the usually diurnal heating. Along the coast, forecast confidence is low for when/how strong the rainshowers will be. High Resolution models show a surge of reflectivity (clouds+ pot. pain) from 03Z-06Z this evening. Confidence is expected to increase later this afternoon with the 00Z TAFs. && .MARINE...Winds and seas continue to diminish as small craft conditions are not expect through the rest of Friday morning for the northern waters. The sea state will continue to diminish Friday as a low pressure system approaches the region, disrupting the northerly wind pattern. Gentle to moderate breezes are expected early this weekend before increasing again in the southern waters. Winds are forecasted to be strongest off the coast of Fort Bragg with near gale to gale force gusts Saturday afternoon. As these winds increase, expect localized areas of small craft advisory conditions with steep wind waves and gusty winds up to 35kts possible. As of right now, the hazard will not be issued due to localized small craft advisory conditions being focused in the far southern waters. breezy north winds are expected to reform and persist through this coming work week. && .FIRE WEATHER...Stronger westerly and northwesterly winds are being recorded Friday across the interior as an unseasonably cold upper trough moves across the Pacific NW (Washington and Oregon). With minimum RH`s around 20-25% on Friday and gusty afternoon and evening winds, elevated to locally critical fire weather conditions are anticipated for eastern Trinity, eastern Mendocino and Lake Counties. Duration of these red flag conditions are not forecast to be long-lived for most of the area. A few higher elevation exposed ridges will likely remain very dry and windy with 8 hours or longer of red flag conditions. A low level northerly speed max (925mb) will likely develop over the Sacramento valley and clip the eastern peripheries of Mendocino and Lake Counties Saturday. Lower overnight humidity and gusty N-NE winds are likely over the higher terrain of Lake and eastern Mendocino (fire weather zones 264 and 277). Once again we may be flirting with locally critical fire weather conditions Saturday and Saturday evening. Our neighboring NWS office in Sacramento has a Red Flag Warning out for cured grassy fuels for elevations below 1000 feet. Otherwise, daytime minimum humidities are forecast to trend drier over the latter portion of the weekend (Sunday) into early next week as temperatures increase each day and winds greatly ease. Also of note is the possibility for thunderstorms over the interior mountains through the end of the weekend and early next week as shortwave energy remains. There is considerable model variability. At this point, there is no compelling reason to deviate from the National Blend of Model thunderstorm probability (NBM) and chances currently look less than 5%. && .EKA WATCHES/WARNINGS/ADVISORIES... CA... Frost Advisory from 3 AM to 8 AM PDT Saturday for CAZ108- 111-114. NORTHWEST CALIFORNIA COASTAL WATERS... None. && $$ NOTE: The full forecast discussion is now regularly issued between 10 am/pm and 1 pm/am. Additional updates will be issued as needed. 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