Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
209 FXUS66 KEKA 312230 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 330 PM PDT Fri May 31 2024 .SYNOPSIS...Conditions in the northern areas are expected to deteriorate this weekend before a short spurt of wetting rainfalls arrives Sunday night into Monday. Southern areas will cool off but are not expected to experience any meaningful precipitation at this time. Next week, temperatures will soar to well above average from the interior to the coast, possibly reaching over 100F in some places. && .DISCUSSION... Northwest California remains under high pressure with mostly clear skies this afternoon. Winds have been less gusty along the coast today as a trough begins to approach the area. A last push of gusty northwest winds in Mendocino and Lake counties will occur on Saturday as the tightest pressure gradient shifts south over those counties bringing gusts to around 30 mph or locally higher on some ridge tops Saturday afternoon and evening. The next main story is the approach of a strong trough Sunday into Monday. The ensembles are indicating precipitable moisture will approach levels at the upper end of what occurs this time of year, several standard deviations above normal, with IVT nearly 90% likely to exceed 500 kg/ms2. Though the target of this moisture is primarily in Oregon, the front will sag into northwest California bringing plenty of moisture to Del Norte and Humboldt counties. Probabilities are nearly 100% of a tenth of an inch or more Sunday night into Monday morning in those two counties but the bigger point of emphasis is that an inch or more in the mountains of Del Norte and northern Humboldt counties is starting to look more likely than just possible. Overall this should only be a beneficial rain but rain rates will need to be further investigated for any risk to the burn scars in Del Norte. Rain chances will quickly decrease farther south and east into Trinity and Mendocino counties where by the farther south portions of Mendocino and Lake counties may see no rain at all. The front will move through the entire region by Monday evening. Quickly behind this front ridging will build back over the west coast allowing temperatures to rebound quickly into the 90s and even to near or exceeding 100 degrees in Lake County on Wednesday and/or Thursday. With the expanding heat there will also be increasing heat risk in the far southeastern portion of the area, particularly near Clearlake. In coordination with the weather office in Sacramento, we went ahead and issued an excessive heat watch from Tuesday through Thursday to highlight this risk. At this time it`s more likely that only heat advisories will be needed but it isn`t impossible that warning thresholds could be reached when the heat peaks mid week. /RPA && .AVIATION... ACV/CEC...VFR then MVFR to IFR overnight. Afternoon conditions are solidly VFR under dry, northerly flow and a well mixed boundary layer. Northerly winds will be gusty through the afternoon at CEC, and there will continue to be lesser gusts at ACV. Moisture will increase with a weak shortwave trough moving through tonight. This will aid in stratus formation along Humboldt Bay and likely transported to CEC through a southerly wind eddy. The shortwave will deepen the marine layer with predominant MVFR ceilings, and movement into IFR. There is a low probability (10 to 20% for LIFR), but the setup does not favor ceilings that low. Light drizzle may also develop around Humboldt Bay, and this could lower VIS to IFR levels as well. UKI....Firmly VFR with occasional NW wind gusts through the afternoon. Stratus will build in from the west into the high terrain with deepening from a weak shortwave trough, but soundings indicate the depth will not be enough to near the valley. /JJW && .MARINE...Gale force gusts will continue over the outer waters through late tonight. Locally gusts up to around 40 kts can be expected near Pt St George and downwind Cape Mendocino into this evening before beginning to ease. Steep waves around 10 to 13 feet are expected to gradually subside today through Saturday, with Hazardous Seas conditions lingering in the southern outer zone 475 through Saturday morning. For the weekend an upper level trough is expected to weaken the winds by Saturday. Sunday a northwest swell around 10 seconds will be the main wave. Initially it is expected to be around 3 feet, but will build to around 6 feet at 10 seconds by Tuesday. Sunday night or early Monday these winds are expected to switch back to northerly once again. Monday and Tuesday it looks like the northerly winds will increase some, but not get all that strong. Mid to late in the week high pressure builds back in and northerly winds will increase once again. && .EKA WATCHES/WARNINGS/ADVISORIES... CA... Excessive Heat Watch from Tuesday morning through Thursday evening for CAZ114-115. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 9 AM PDT Saturday for PZZ450. Small Craft Advisory until 3 AM PDT Sunday for PZZ455. Gale Warning until 10 PM PDT this evening for PZZ470-475. Hazardous Seas Warning from 10 PM this evening to 6 AM PDT Saturday for PZZ475. && $$ 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