Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
334 FXUS66 KEKA 082146 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 246 PM PDT Mon Jul 8 2024 .SYNOPSIS...Heat will slightly ease this week though highs will remain stubbornly above average with widespread moderate HeatRisk. Otherwise calm, dry weather will continue with a regular marine layer along the coast. && .DISCUSSION...High pressure has finally started to weaken and drift eastward today. Marine influence has markedly increased in response with extensive marine stratus along shore. Coastal sites today have hovered in the low 60s. Inland sites have still stayed hot, but have gracefully stayed below 110 degrees at least. Additionally, growing amounts of smoke or evident stuck in valleys around the Shelly Fire. SOme of this smoke has began drifting into Trinity and northern Humboldt Counties. Air quality monitors are showing pockets of moderate air quality as far south as Willow Creek and Trinity Center. Temperatures will fluctuate through the week as high pressure ebbs and flows under the influence of a subtle upper level shortwave. General high pressure with encourage continued above normal temperatures and smoke accumulation in valleys near the Shelly fire. In the short term, heat will further ease through Tuesday as high pressure moves east and onshore flow increases and brings more marine influence. That said, temperatures will still remain stubbornly around 100 for most of the interior. That said, weakened thermal belts will generally bring much more overnight relief helping ease HeatRisk closer to moderate and major levels. Cool marine influence and stratus will be consistent all along the coast. A brief build up of high pressure Thursday and Friday will increase temperatures back up about 5 degrees, bringing highs back near 110 in the interior and at least isolated major HeatRisk. Models are in very good agreement that high pressure will finally begin to ease east this weekend, bringing interior highs back closer to 90 by Sunday. In addition, there are indications that some monsoon moisture will spread aloft Friday into the weekend. The vast majority of ensemble members focus moisture east, but significant uncertainty remains regarding the moistures interaction with low pressure offshore. Should moisture move further west, isolated dry thunderstorms are possible (currently <10 % chance) over high terrain. /JHW && .AVIATION...The trickiest part of the forecast will be dealing with stratus at the coastal terminals. Probabilities for ceilings below 1K feet do not drop below 50 percent for these locations according to NBM, so any scattering as indicated in the forecast should be short-lived as most models and probabilities of ceilings increase as the night wears on. Latest satellite image loops indicate a struggle for further erosion of the coastal stratus today as well. Bumped up wind gusts a bit for this afternoon for KUKI, as favored from NBM solutions. /MH && .MARINE...Main problem continues to be gale force potential late Wednesday night into Friday morning behind a cold front. Strong sustained north winds over 30 KTS are forecast for the outer waters during this time and the forecast needs to be monitored. The small craft for the outer waters stretching through tonight into Tuesday morning might might continue more due to waves meeting low-end steepness criteria, rather than wind speeds and gusts. Also, wind and waves may warrant small craft advisories starting on Wednesday/Wednesday night before ramping up stronger on Thursday. /MH && .FIRE WEATHER...The peak heat and dryness have thankfully passed, but above average temperatures and low RH will promote elevated fire danger though the week. Interior valleys will continue to see minimum RH as low as 10 percent though increased marine influence will greatly moderate near coastal valleys. Winds will remain mostly gentle and terrain driven with gusts below 15 mph except in terrain funneled areas. Models continue to suggest a plume of monsoonal moisture late in the week Friday into the weekend. While the vast majority of models place the plum east of the area, there remains a small (< 10%) chance of isolated dry thunderstorms over high terrain late in the week. /JHW && .EKA WATCHES/WARNINGS/ADVISORIES... CA... Heat Advisory until 8 PM PDT this evening for CAZ102-104- 106-112. Excessive Heat Warning until 8 PM PDT this evening for CAZ105-107-108-110-111-113>115. NORTHWEST CALIFORNIA COASTAL WATERS... Gale Watch from late Wednesday night through Friday morning for PZZ470-475. Small Craft Advisory until noon PDT Tuesday 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