Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
221 FXUS66 KEKA 251144 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 444 AM PDT Tue Jun 25 2024 .SYNOPSIS...Interior warm and dry conditions continue today while marine stratus dampens coastal temperatures. Potential for high- based storms today as mid-level moisture pushes into NorCal. An upper level disturbance mid-week will allow for relatively cooler temperatures through Thursday. Warming trend returns for this weekend into next week. && .DISCUSSION...Marine stratus once again enveloping the Humboldt coast. Strong southerly wind reversal allowing the leading edge to migrate north to the Oregon coast - a similar pattern is beginning to appear along the southern Mendocino coast. HREF showing strong signatures for <1000 ft ceilings continuing through tonight without much reprieve, although the stratus shield may hover nearly flush with the coastline this afternoon, allowing for some breaks before pushing onshore again this evening. More significant reductions in visibilities expected early Wednesday morning. IR satellite and radar showing ongoing northeasterly progression of convective showers from the central coast. Very light returns beginning to reach southern Lake and coastal Mendocino counties as of early this morning, but minimal lightning flashes remain well offshore. CAMS guidance anticipating more substantial albeit isolated returns developing around 15Z in Lake and Mendocino counties. With NAM model guidance indicating wetter mid-level RH values reaching further into Humboldt and Trinity counties this afternoon, potential for scattered showers is certainly possible further north. Main focus is still on Mendo and Lake counties, especially as increasing temperatures induce instability this afternoon. Lower levels are consistently dry, limiting development but still posing a threat for gusty winds and potential for dry lightning strikes. Once again, coastal highs will remain dampened by marine stratus redevelopment while hot temperatures are forecast for the interior. NBM probabilities are favoring highs in the low to mid 90`s again in the valleys of Southern Mendocino, Lake and eastern Trinity counties. Daily surges in diurnally driven NW flow may be interrupted by isolated storm outflow. Otherwise, a pattern change is still expected early Wednesday into Thursday as an upper level trough drops into the PNW, inducing relative cooling of temperatures and slightly elevated westerly winds. This will be a concern for fire weather in the case of any dry lightning starts - NW wind gusts 15-25 mph are possible alongside RH`s <30% in Lake/S Mendocino counties. NBM temp probabilities drop off significantly around 90 degrees for the interior valleys on Wednesday, mid-80s on Thursday following a weak frontal passage. Broad ridging looking more likely this weekend for another warming trend before potential for another disturbance early next week. && .AVIATION...Expansive LIFR stratus has developed along the north coast early this morning, while visibilities have remained VFR. This low cloud is expected to retreat to the immediate coast by late morning, but with lighter winds forecasted today it may linger just offshore before moving back onshore this evening and tonight. Otherwise, widespread VFR conditions will persist for the interior with normal summer conditions. && .MARINE...Northerly winds continue to weaken today, and are forecast to significantly weaken tomorrow. Meanwhile a minor northwest swell of 5 feet at 11 will slowly decay today. Northerlies are forecast to remain below 15 kt for most zones during Tuesday through Thursday morning, aside from the persistent 15-20 kt northerlies expected directly downwind of Cape Mendo. Northerlies are expected to strengthen again Thursday afternoon into this weekend. && .FIRE WEATHER...Reflectivity returns beginning to cross into Southern Mendocino and Lake counties this morning as mid-level moisture pushes north into the region. Low potential for isolated dry lightning amidst within elevated convection. Still, some of these storms could produce gusty outflow winds. Increasing NW flow on Wednesday combined with <25% RH values may pose a fire weather risk in the case of any potential starts this afternoon. Greatest threat to fuels in areas below 2000 feet. && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 3 AM PDT early this morning for PZZ455. Small Craft Advisory until 9 AM PDT this morning for PZZ470- 475. && $$ 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