Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
891 FXUS66 KEKA 281157 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 457 AM PDT Fri Jun 28 2024 .SYNOPSIS...Coastal stratus and patchy drizzle will scour out with increasing NW winds. Slightly elevated daytime RHs expected as a shortwave moves through the region on Saturday, enhancing marine influence inland. Warming and drying trend expected to intensity early next week - fire weather and heat risk have potential to become increasingly critical heading into the July 4th holiday. && .DISCUSSION...Coastal stratus is exhibiting more substantial coverage this morning than previously expected. A southerly wind reversal set up allowed <1000 foot ceilings to reach Point St. George and coastal Oregon, while moist onshore flow continues to advect low clouds into adjacent river valleys. Patchy coastal drizzle is also possible this morning, especially around Humboldt Bay. The coastal pressure gradient will continue to enhance diurnally driven NW winds this afternoon as Pacific high pressure builds into the interior thermal trough. HREF indicating high probabilities of gusts >35 mph on coastal headlands including Crescent City, Cape Mendocino and the surrounding King Range. Meanwhile, increasing temperatures in the Great Basin and desert SW continue to build into the West Coast. NBM exhibits high probabilities of interior valleys >90 degrees this afternoon, aligning with short range deterministic models. With increasing temperatures, min daytime RH values can be expected to drop into the mid teens and low 20`s in Lake and interior Mendocino and Trinity counties. Interior wind gusts are not expected to exceed 15-20 mph, but a slight fire weather risk still exists. A weak upper shortwave is expected to disrupt the marine layer and bring some mid-level moisture to the area along a weak frontal boundary Saturday morning. NW winds 5-15 mph are forecast across the interior through late Saturday night, with gusts 20-30 mph on exposed terrain. Surface RH`s will be slightly elevated as this trough sustains marine influence for coastal counties through the weekend, with interior valleys not expected to drop below 20- 25% min daytime RHs. Even so, these gusty winds will pose potential for fire weather risk. Long-range models are becoming increasingly confident in anomalously warm ridging building into the eastern Pacific beginning late Monday, coupled with potential for widespread min RHs in the teens and single digits by mid-week amidst NE flow. Interior temperatures have a fairly high probability of reaching the upper 90`s and low 100s with coastal temperatures in the 60`s and low 70`s from Tuesday through late next week. Stay tuned for continuous updates on potential for significant HeatRisk and heightened fire weather conditions. && .AVIATION...IFR/LIFR conditions with OVC layer at FL003-FL006 and visibility in mist is observed along the North Coast early this morning, while VFR conditions prevail at UKI. Coastal stratus are expected to lift and mix out during the afternoon with the increasing northerly winds. After 20Z, a period of VFR conditions is expected for all terminals. Later this evening into Saturday morning, stratus will redeveloped around Humboldt Bay and vicinity, including ACV. Offshore NE flow component and breezy northerly winds will remain generally free of low clouds in CEC. Surface winds very light and variable in the morning, becoming breezy NNW at 10-20 kts after 20Z with occasional stronger gusts...primarily at KCEC where gusts to around 35 kt is possible. && .MARINE...Northerly winds will continue strengthening today, with the strongest winds south of Cape Mendocino where near gale to locally gale force gusts is likely. Short period seas will pick up to around 8 to 10 feet at 8 to 9 seconds late afternoon and evening as result. Winds will begin to ease slightly over the weekend as a trough moves through. However, winds are forecast to remain elevated over the southern waters. Monday, winds are forecast to strengthen again as a high pressure offshore begin to builds in quickly in the wake of the trough. A thermal trough is then expected to develop near the coast Monday night/early Tuesday and favor moderate to strong pressure gradient. Widespread strong to near gale force winds and very steep, hazardous seas is forecast for early-mid next week. && .FIRE WEATHER...Gusty NW winds combined with 15-25% minimum daytime RH values may pose a brief increased fire weather threat this afternoon and evening, especially in Lake and interior Trinity and Mendocino County. Greatest threat to fine fuels in areas below 2000 feet. && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 11 PM PDT Sunday for PZZ455-475. Small Craft Advisory until 9 AM PDT Sunday for PZZ470. && $$ 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