653 FXUS66 KEKA 132141 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 241 PM PDT Mon Sep 13 2021 .SYNOPSIS...The interior will heat up heading into Tuesday, with localized triple digit readings. Sunshine will be muted in some areas by smoke and haze. The coast will remain cool, but with decreasing marine layer clouds through mid-week. Rain will be possible for portions of our region over the weekend. && .DISCUSSION...An upper level shortwave moving over the area today has stalled further warming above yesterday's highs. Early this afternoon, the hottest valleys are just reaching 90. Winds are generally modest and terrain driven. The shortwave has helped push gales closer to shore, brining some extra breezy headlands today. Stratus has mostly cleared from the coast, stubbornly staying only around Humboldt bay. Stratus should mix away later this afternoon and offshore flow will dampen any cloud resurgence overnight. This same offshore flow will bring overnight gusty winds to ridges in Del Norte County and will also push smoke back towards shore. Behind the the wave on Tuesday, ridging will resume aloft with a vengeance. Temperatures will quickly warm with hot valleys, especially in Mendocino and Lake counties, likely touching 100. Smoke further north will likely depress temperatures somewhat. Though above average, conditions generally fall below advisory criteria. Weak offshore flow continuing on Tuesday may help keep coastal stratus away while continuing to push smoke towards shore. Warmer air aloft helping the inversion take hold by Wednesday morning should help weaken smoke transport and bring some return to coastal stratus. The flattening of the ridge Wednesday and Thursday should keep weather later in the week dry and seasonable with mostly modest terrain winds. Friday into the weekend, model clusters now largely agree on a deep trough entering the area. This will push temperatures cooler with weekend highs forecast well below normal by Saturday. On shore moisture advection brings a chance of wetting showers over the weekend, mostly on Saturday. ECMWF EFI concentrates rain along the northern coast, but there is a slight chance of rain across most of the area. The GEFS generally spreads precipitation further inland, but it seems to have pulled back a bit today. Current confidence in coverage and amount of rain is very low, so future refinement is expected. /JHW && .AVIATION...A ribbon of stubborn stratus is finally dissipating from the north coast allowing vfr conditions to take hold...at least temporarily. Coastal terminals will likley fill in again later this afternoon or evening as winds and drying decouples and the marine layer deepens. Expect another late period of mixing tommorow with another night of mvfr/vfr periods forming along the coast. Interior sites should remain vfr through the taf cycle. EYS/JT && .MARINE...Significant wave heights around 11 feet at 8 to 9 seconds will continue as wind waves and swell combine into a hazardous sea state. Gale conditions will persist into Tuesday morning with hazardous seas lingering soon after. A Gale Warning is in place for the northern and southern outer waters for the next 24 hours as the thermal trough continues to strengthen. Expect elevated seas to persist through the week with the return of larger significant waves early Thursday morning. Inner waters will see a reduction in both seas and waves beginning Wed and lasting through the weekend. EYS/JT && .FIRE WEATHER...Generally calm, dry conditions continue today with humidities already touching the upper teens in the hottest valleys. Winds are mostly weak and terrain driven with normal afternoon gusts around 15 mph. Recoveries tonight are expected to be poor with interior ridges not improving beyond 30. Humidities are expected to remain dry through Wednesday at higher elevations with minimum RHs just above 10 by Tuesday. Elevated northeasterly winds are expected to mix down late this afternoon and overnight with the passage of a shortwave trough aloft. Infrequent gusts at higher elevations may crest around 30 mph. These winds are expected to be very dry with minimum RHs in the low teens. Recoveries should be very poor tonight with maximum RH under 30 on ridgetops. Models have somewhat backed off on winds and dryness today, making critical conditions more localized to peaks and ridges. Still, left the Red Flag warning for the area. Cooler temperatures and moister RH will gradually settle into the area Wednesday and beyond. A strong upper level trough may bring a slight chance of showers into next weekend, though guidance remains uncertain on coverage and intensity. Most guidance points towards rain being focused on the northern coast. There is a possibility of enhanced terrain winds in front of the trough passage on Friday. High resolution guidance should bring clarity over the next couple of days. /JHW && .EKA WATCHES/WARNINGS/ADVISORIES... CA... Red Flag Warning until 10 AM PDT Tuesday for Lower Middle Klamath-Upper Smith. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 6 AM PDT Wednesday for Cape Mendocino to Pt Arena out 10 nm-Pt St George to Cape Mendocino out 10 nm. Gale Warning until 6 AM PDT Tuesday for Cape Mendocino to Pt Arena 10 to 60 nm-Pt St George to Cape Mendocino 10 to 60 nm. && $$ 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