372 FXUS66 KEKA 211127 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 427 AM PDT Sat Aug 21 2021 .SYNOPSIS...Temperatures will cool a bit this weekend. Marine moisture is expected to move further inland as marine stratus begins to return. Smoke currently blanketing the area will shift further east. Looking to next week a modest drying and warming trend is expected. && .DISCUSSION...The upper level trough impacting the area is clearly shown on water vapor satellite this morning as it moves through Washington and Oregon. This has increased the westerly wind aloft this morning and is ushering in cooler air. There is also an increase in surface moisture. This onshore flow is bringing some marine clouds, however the majority of them are south of Cape Mendocino. The cooler air aloft has also weakened the marine inversion making it likely these clouds will mix out this afternoon. This afternoon inland temperatures will only be in the upper 70s to upper 80s. The smoke from the fires will generally be pushed off to the east of the fires. The smoke may inhibit afternoon warming in some locations again. Tonight as the trough continues to push off to the east winds over NW CA start to become northeast to east again. The remain fairly light, but the HRRR smoke models shows the smoke pushing towards the coast. With the lighter winds the model shows it staying away from the coast and not dropping south into Mendocino or Lake counties. Sunday afternoon the typical westerly afternoon winds push the smoke back to the east. Monday through Wednesday next week the models show a fairly zonal flow setting up on the west coast. Overall there will be a gradual warming trend through this period although temperatures will generally remain near seasonal normals. Occasionally weak shortwaves moving into the Pacific Northwest may drop temperatures a couple degrees. Overall this will generally keep winds mainly terrain and diurnally driven. There will likely be some marine clouds around, but with the moderate temperatures aloft the marine inversion will be relatively weak allowing for afternoon clearing. Thursday and Friday most of the ensembles are showing a period of ridging building over the west coast and bringing a return to above normal temperatures. The ensemble clusters still highlight differences in how quickly the ridge builds in and how strong it will be. There is some agreement that Friday will be the hottest day. MKK && .AVIATION...Orographically forced stratus is occurring in the vicinity of Humboldt Bay early this morning, and patches of that stratus have occasionally lowered ceilings at KACV. However, skies are forecast to generally clear going into the afternoon. Mainly clear skies will also be probable at KCEC, though haze will be possible as sea spray is enhanced with the onset of afternoon northwesterlies gusting from 20 to 30 kt. Otherwise, wildfire smoke and haze will be probable across the interior this morning, followed by partial clearing during the afternoon occurring in response to increasing low-level westerly flow. In addition, short-term high resolution model guidance continues to indicate possible stratus spreading north across the Russian River Valley this morning, with ceiling impacts possible at KUKI. Garner && .MARINE...North-northwest winds are forecast to weaken across most of the coastal waters today. However, locally windier conditions with gusts to 35 kt are expected near Pt St George and the south side of Cape Mendocino. Widespread steep hazardous seas will subsequently subside with the decrease in wind speeds. After the weekend, periods of small craft winds and seas will be likely during the first half of next week. Thereafter, model guidance indicates gale force northerlies will redevelop on Thursday and Friday. Garner && .FIRE WEATHER...THe upper level trough moving by to the north of the area has brought better recoveries this morning. The lowest recoveries in the east are around 50 percent on the ridges with areas farther west and in the valleys significantly better. This afternoon RH is expected to drop into the 20s and temperatures will be slightly below seasonal normals with highs only in the 80s. This afternoon northwest winds will increase across the area. The winds aloft are increasing and this will increase the winds on some of the higher ridges. In addition these northwest winds will enhance the typical afternoon winds up the northwest to southeast valleys. Local gusts of 20 to 25 mph are possible in the funneled areas. Sunday the flow becomes more zonal. This will allow temperatures to warm slightly to around seasonal normals. RH will start to drop slightly as well. Monday through Wednesday the flow remains fairly zonal. Temperatures may warm a degree or two each day and both afternoon RH and overnight recoveries will gradually decrease. The winds will generally be fairly light and terrain driven. Late in the week the models are showing high pressure building in bringing back above normal temperatures. The ensemble clusters highlight the uncertainty on the strength and timing of this ridge. MKK && .EKA WATCHES/WARNINGS/ADVISORIES... CA...None. NORTHWEST CALIFORNIA COASTAL WATERS... Hazardous Seas Warning until 11 AM PDT this morning for PZZ470-475. Hazardous Seas Warning until 8 AM PDT this morning for PZZ450. Small Craft Advisory until 6 PM PDT this evening for PZZ455. && $$ 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