Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
399 FXUS66 KEKA 112205 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 305 PM PDT Sat May 11 2024 .SYNOPSIS...The ridge of high pressure is weakening and this will allow coastal clouds to return tonight and Sunday night. Temperatures will be cooler and an inland shower or two is expected on Sunday. Monday cooler temperatures will continue before a warmup again Tuesday and Wednesday. && .DISCUSSION...A weak shortwave is approaching the area today and this is nudging the high pressure off the east. This has weakened the offshore flow and this has allowed stratus to drop down from the north. As of 2pm it is getting very close to the coast. This is expected to rapidly expand this evening once the daytime heating diminishes. This has also allowed some flat topped CU to develop over the interior areas. A few sprinkles are possible today, but otherwise it looks dry. Tonight this approaching shortwave may bring some drizzle to the coast. Sunday the coast may take some time to clear out and the immediate coast may not clear at all in some areas. Sunday afternoon there is a chance for some showers and possible a thunderstorm in northern Trinity county, but coverage should be fairly limited. Inland areas will be cooler than today by around 5 degrees or so with highs in the mid to upper 80s in the interior valleys. Sunday night into Monday the flow starts to shift again and offshore flow is possible once more. It is uncertain how quickly this will clear out the coastal clouds, but it should help with clearing on Monday. The northerly winds are also expected to increase through the day on Monday. Tuesday and Wednesday high pressure is expected to build in along with offshore flow. This may bring highs in the mid 60s along the coast and low 90s inland. A few areas of the warmer valleys are expected to see a moderate heat risk. Late in the week the ensemble clusters show different solutions. Two of the clusters show a trough bringing a return to cooler while the other two keep high pressure over the area. This could mean the difference between highs around 90 or highs around 60. MKK && .AVIATION...VFR conditions across the region will continue for the next few hours with light NNW winds. A broad shield of marine stratus is gradually enclosing the NorCal coast from the outer waters, accompanied by a southerly coastal wind reversal reaching north from the Mendocino coast and a northerly plume descending from southern Oregon. Hi-res models suggest IFR ceilings (<1,000 ft) and potential for reduced visibilities beginning just before sunset and persisting overnight for coastal terminals. Light SE offshore winds will have minor effects on the coastal extent of the stratus deck. Some uncertainty still remains regarding the lasting strength of the marine layer into Sunday and how much fog will reduce visibilities, especially early tomorrow morning. UKI expected to remain clear and dry with light offshore winds overnight. && .MARINE...Light diurnally driven WNW winds will continue through the weekend as minor NW swells dominate the sea state. Northerly winds expected to increase late Sunday night into early Monday morning, forming two expansion fans downwind of southern OR and of Cape Mendocino. Gusts expected to rapidly develop in the outer waters through the day Monday, with mid-range models currently forecasting 40 knot gusts or greater beginning early Tuesday and continuing through mid-week. Steep wind wave response expected to exceed 10 feet late Monday across all zones, potentially approaching 14-16 feet by Tuesday and Wednesday in the outer waters. Seas expected to diminish slightly in the latter half of the week but remain near or greater than 10 feet, depending largely on the persistence of offshore winds. && .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