Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
228 FXUS66 KEKA 212109 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 209 PM PDT Tue Jul 21 2026 .KEY MESSAGES... * Warmer temperatures peak today with minor to moderate HeatRisk. * Chance of showers and thunderstorms across the region Today and Wednesday, with the biggest threat for the interior on Wednesday afternoon. * Near or slightly below normal temperatures late in the week. .SYNOPSIS...Monsoonal moisture will continue to bring high clouds, stray showers, and potential for isolated thunderstorms today and Wednesday. Today will, also, bring peak heating for the interior this week. Drier weather is expected late in the week with temperatures near or slightly below seasonal normals. && .DISCUSSION...Generally, the hottest high temperatures for this week peak today with highs in the mid to upper 90s for the warmer valleys and up to 100 in the hottest valleys. Late this afternoon and evening some models show a small amount of instability; however, forcing is generally lacking for thunderstorm development. Still, one or two are possible in northern Trinity County in the evening. However, more isolated light rain showers are likely through the afternoon and evening. Wednesday, the area of low pressure starts to move past the area bringing a slightly more forcing with some instability in the afternoon and evening. This is expected to be the most likely time for thunderstorms to develop this week. However, if any storms do form they will be moving north and may move into Siskiyou county fairly quickly. Thursday, the upper level trough is expected to get closer to the area and this is expected to start bringing cooler temperatures, back to near or slightly below normal with highs in the upper 80s to mid 90s. This is expected to bring some stronger west to southwest winds in the afternoon. Similar temperatures and winds are expected to continue on Friday. For details see the fire weather section. High pressure is expected to bring warmer temperatures to the area for the weekend with dry weather. && .AVIATION...High clouds with the occasional shower continues over Northwest California terminals into the evening. Generally, VFR conditions are expected to persist with clearing for the interior later this evening. Coastal stratus is expected to make a return for coastal terminals overnight tonight. Mostly MVFR to IFR ceilings with periods of LIFR are anticipated into early tomorrow. && .MARINE...Below advisory northerly winds are forecast through the rest of the day. Winds will gradually shift to southerly as a low pressure system that was Tropical Storm Elida passes by the coastal waters. A 3 to 4 foot southerly swell at 12 seconds is moving through the waters along with a 2 foot northwest swell. These conditions are generally expected to continue through much of the week. The swells will fluctuate slightly, but generally remain small. Winds are expected to increase slightly to 10 to 15 kt Tuesday night and early Wednesday before diminishing again to less than 10 kt. Thursday afternoon northwest winds start to pick up once again in the southern waters to around 10 to 15 kt. Winds continue to increase over the weekend. MKK && .FIRE WEATHER...Isolated showers or virga are anticipated to continue this afternoon and evening. There is a low probability for some isolated thunderstorms, mostly in NE Trinity County. Wednesday, the upper level low related to the departing tropical system moves closer to the area which will increase the potential for some thunder in the afternoon. Confidence remains low on this, but have added thunderstorms to the forecast Wednesday afternoon and evening. Thursday and Friday the threat for thunderstorms diminishes; however, some stronger west to southwest winds are expected. At this point it looks like the RH will be too high to warrant a fire weather watch. Will likely add a headline to the forecast once it gets within range of the higher resolution models if the winds remain in the forecast. MKK && .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