Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
690 FXUS66 KEKA 052158 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 258 PM PDT Sat Oct 5 2024 .SYNOPSIS...Unseasonably high temperatures continue across the interior through the weekend with weak high pressure ridging. A more typical cool and moist fall-like pattern expected to develop over the course of next week, with slight potential for rainfall by the end of the forecast period. && .DISCUSSION...Temperatures will be unseasonably warm again today and tomorrow as high pressure builds in from the Eastern Pacific. Highs are expected to reach into the mid to upper 90`s across interior counties, with isolated valley highs potentially approaching 100 degrees in Mendocino and Lake Counties. Moderate heat risk in these areas can affect individuals sensitive to heat and without adequate cooling/hydration. Additionally, broad offshore flow will keep daytime RH`s low and help to push the heat further towards the coast. Hi-res models indicate a high probability of temperatures >75 degrees both today and Sunday for coastal areas spanning Cape Mendocino through Shelter Cove. Fort Bragg and Point Arena lag behind only slightly in the low 70`s - well above the monthly average. The last push of elevated NE offshore flow will continue to develop overnight tonight and Sunday evening, with gusts 10 to 15 mph possible south of the Cape and along exposed ridges. Min daytime RH`s will struggle to rise above the mid to upper teens across the interior. This will continue to pose an elevated fire risk especially in Lake County, despite no longer reaching Red Flag criteria. Satellite imagery is beginning identify some mid-level moisture pushing north from central CA in the form of cirrus and broken cumulus clouds. Short to mid-range models show this surge of slightly elevated RH`s above 700 mb coinciding with some isolated reflectivity Sunday afternoon as a weak upper level shortwave approaches. However, the profile still looks to be exceptionally dry through the surface and will likely not support more than a few sprinkles/virga given a lack of instability (as per the previous discussion). Otherwise, temperatures and RHs are still expected to trend more cool and moist, gradually through mid-week and then more significantly as NW onshore flow becomes more robust. Long-range models are highlighting potential for 20-25 mph winds developing Monday and Tuesday afternoon in southern Mendocino and Lake counties as the coastal pressure gradient strengthens. Daytime highs are expected to fall into the upper 70`s and low 80`s. NBM probabilities of >0.1 in of rainfall are still hovering around 50-60% for late Friday into early Saturday, but there is still a lot of room for change. && .AVIATION...Clear skies this afternoon with VFR conditions expected to prevail through the early evening. Offshore flow this morning kept the stratus offshore before easing. Northwesterly winds have become a bit more consistent at KCEC and KACV with 5 - 8 kts. Winds are expected to ease this evening. HREF shows mid level clouds coming in tonight from the south, sparsely covering Mendocino and Lake county. Model soundings also confirm moisture in the mid levels with decent flow aloft. Offshore stratus and low covering cloud return is forecast to return Saturday morning but maybe not as impactful to where flight categories are affected. Otherwise, light southerly winds tonight and visibility of less than 0.5 mile at 30% probability for KCEC and KACV. Prevailing VFR conditions at KUKI through the TAF period. /EYS && .MARINE...Northerly winds will persist through mid next week as the thermal trough remains strong over the interior in response to continued warm temperatures over the western states. However, with a broad trough over the eastern Pacific, the pressure gradient will remain not particularly tight over the waters limiting the strength of the northerly winds. Gusts to around 25 kt will be possible over the southern outer waters through the weekend and into early next week while elsewhere winds will be lighter. This will be particularly true in the inner water zones with the lightest winds inside of 10 nautical miles north of Cape Mendocino. Seas will be highest south of the Cape where the winds are the strongest. A building northwesterly swell on Monday may push the overall sea state to a height requiring small craft advisories. /RPA /EYS && .FIRE WEATHER...Unseasonably warm and dry conditions will continue through the weekend, with daytime RH`s remaining in the low to mid- teens across the interior. Elevated NE winds at 5 to 10 mph with isolated gusts approaching 15 mph are possible overnight and late Sunday afternoon, further enhancing warming and drying closer to the coast. A pattern shift is expected early next week as NW onshore flow promotes cooler and drier conditions. Gusty NW winds are possible Monday and Tuesday afternoon as the coastal pressure gradient strengthens - gusts exceeding 20 mph are possible across southern Mendocino and Lake County, especially on exposed terrain and may pose an elevated fire weather risk. Otherwise, daytime temperatures are expected to be in the upper 70`s and 80`s by midweek with overnight RH recoveries 50 to 75%. Light precipitation is still possible on the horizon for late next week. && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... None. && $$ 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