Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
568 FXUS66 KEKA 061302 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 602 AM PDT Thu Jun 6 2024 .SYNOPSIS...Interior heat will peak today with isolated areas of major heat risk expanding into the eastern Trinity River Valley in addition to Lake County. There remain a very slight chance of isolated thunderstorms over high terrain this afternoon. Conditions will ease into the weekend. && .DISCUSSION...Surface high pressure and associated heat will peak across interior valleys today. Most of Lake COunty especially is already starting out warm with overnight lows in the mid 60s. NBM continues to put a 70 to 90% chance of highs over 100 today in southern Mendocino and Lake Counties and even up into the Trinity River Valley. Moderate to locally major heat risk is highlighted across interior Valleys but especially in Lake County and along the eastern Trinity River. Beyond temperature, strong solar heating will also help increase surface instability. At the very least, this will most likely generate more impressive and visible afternoon cumulus clouds over high terrain. Model soundings have eased off of instability a a bit still show up to 1000 J/Kg of CAPE late this afternoon over high terrain. Despite this fact, total column moisture is marginal at best and any lifting would have to break through a midlevel cap and reach near 15 kft for thunderstorm formation. These factors make the formation of isolated afternoon thunderstorms possible though unlikely (10 to 15% chance) late this afternoon and evening. Closer to the coast, high pressure will continue to promote a thin but persistent marine layer with temperatures solidly in the 60s and stubborn coastal fog and stratus. Compared to yesterday, however, Strong heating, however, any marine clouds have been particularly patchy and ragged, likely promoting quick clearing today. High pressure will weaken into the weekend with a narrow trough crossing the area around Sunday. Such a pattern will push marine influence further inland and bring interior temperatures back into the low to mid 80s. With little moisture to speak of, however, essentially no ensemble members show rain with the trough beyond coastal drizzle. That said, increased midlevel moisture with a bit of upper level support and June sun could promote isolated afternoon thunderstorms. Probabilities remain low (less than 20%) but chance should be watched closely, especially Saturday. Essentially all cluster ensemble members show a ridge of high pressure centering over the Pacific Northwest early next with low pressure stalled off the California Coast. Such a pattern will bring typical to slightly above average summer temperatures. Only about 15% of ensemble members currently show any temperatures hotter than the current heat wave. /JHW && .AVIATION...Stratus has been limited in development during the early morning hours. KCEC will have IFR flight categories through the morning with occasional bouts of MVFR as visibility degrades with calm winds aiding in mist or fog development and obscuration. Ceilings will hover around 1000 feet before lifting out this afternoon as model soundings do show tempertures inversion yet a dry profile throughout. Expect stout northerly winds at KCEC with gusts form 20 to 24 kts this afternoon as pressure gradients steepen from a strengthening upper level low off the Canadian coast. Low level wind shear does not look to be an issue at this time as the wind profile is fairly consistent in direction and uniform with respect to height. KACV has a closer temperature and dewpoint profile with model soundings from MOS guidance which may only result in minor obscuration as HREF indicates MVFR categories this afternoon. A return to LIFR/IFR conditions early Friday morning is likely with light winds. VFR conditions will prevail at KUKI with light southerly winds overnight into Friday. The afternoon northerly gusts are not being signaled by guidance today. /EYS && .MARINE...The northwesterly swell is diminishing yet conditions at sea remain hazardous for small crafts as mid period swell and locally generated wind waves persist. Gale conditions for the northern outer waters will begin in the late afternoon around 22z and could last through to Friday morning around dawn. The Gale conditions in the southern waters will reduce in coverage yet remain elevated south of Cape Mendocino. Steep northerly waves persist in the southern outer and inner waters with northerly groups 10 to 11 feet, with as many seconds in period. NW swell around 6 to 8 ft at 12 to 13 seconds linger as well. All zones are expected to subside to sub-10 foot wave heights by late this week and early weekend as the swell subsides. /JMM /EYS && .EKA WATCHES/WARNINGS/ADVISORIES... CA... Beach Hazards Statement until 9 AM PDT this morning for CAZ101-103-104-109. Heat Advisory until 8 PM PDT this evening for CAZ114-115. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 9 PM PDT this evening for PZZ450. Gale Warning until 9 AM PDT this morning for PZZ455-475. Hazardous Seas Warning until 3 PM PDT this afternoon for PZZ470. Gale Warning from 3 PM this afternoon to 3 AM PDT Friday for PZZ470. && $$ 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