Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
900 FXUS66 KEKA 170717 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 1217 AM PDT Tue Jun 17 2025 .SYNOPSIS...Increasing afternoon breezes and some fire weather concerns in southern Mendocino and Lake County early this week. Warmer temperatures and minor HeatRisk concerns mid week. Much cooler temperatures and chances for light rain Friday and through the weekend. && .DISCUSSION...Weak ridging has started to build into the area as a trough moves to the east. Inland valley temperatures will warm into the low to mid 90s, with some upper 90 in Lake County on Wednesday. This will present minor HeatRisk concerns. Temperatures will trend lower next Thursday as another weak shortwave trough passes. Northwesterly winds strengthen behind the front, particularly in Trinity, Mendocino, and Lake Counties. NBM probabilities for gusts over 35 mph Friday are around 40-75%, while ridgetops are likely to have higher gusts. This could be a fire weather concern as afternoon relative humidities remain dry in the eastern portions of the area. An anomalously strong trough for this time of year is then forecast to dive south into the region next Friday. NBM currently holds up to a 50% chance for over 0.1 inches of rain Friday through Saturday. Some ensemble members show chances for higher amounts. There is the potential some of this precipitation may be in the form of thunderstorms with steep lapse rates and elevated instability. Depending on the timing and how cold the system is, a few snowflakes are possible over the highest peaks. NBM has high probabilities for low temperatures in the 30s for much of Trinity and the coldest valleys of Mendocino and Humboldt Saturday and Sunday mornings. If skies remain relatively cloud free, some frost is not out the question in the coldest valleys. && .AVIATION...17/06Z TAFs...There is a 28-37% chance of ceilings coming down below 500ft tonight and an even better probability of <1000ft ceilings overnight at KCEC. A decent probability (66%) of shorter duration IFR conditions exist at KACV overnight. Development is not obvious as of 6z but a shallow inversion can be seen in the soundings. Gusty northerlies are likely at KUKI by Tuesday afternoon, lasting into the evening hours with VFR prevailing. /EYS && .MARINE...Winds are forecasts to ease from the northern outer waters as small craft advisories have expired. As the winds and wind waves die down, a small mid-period NW swell enters the area waters early Tuesday morning. These calmer conditions will be short lived however, as fresh breezes return to the southern waters Wednesday through the rest of the week. Depending on the wind wave responses to these winds, small craft advisory well could be issued for Wednesday in the southern waters. Later in the week and into the weekend, a late season cold front passing over the PacNW will cause the land-sea temperature difference that creates the pressure gradient which drives our coastal winds to weaken, bringing gentle- to-moderate breezes and a mid-period small NW swell to the coastal waters. && .FIRE WEATHER...Northwesterly afternoon winds remain breezy in the interior today and Wednesday, particularly in southern Mendocino and Lake. High temperatures are forecast to rise a few degrees, continuing the warm and dry trend. RH recoveries remain good, but afternoon RHs dip into the teens or low 20s, which does present a localized elevated fire weather threat in the afternoons and evenings. Winds spike up Thursday and Friday with stronger, gusty winds possible in the eastern portions of the area in the afternoons. Min RHs are forecast to be slightly higher, but remain low. A cold upper low is forecast to dive south into the region late this week and into the weekend. This will bring cooler temperatures and a chance for light rain to the area. && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. 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