Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
167 FXUS66 KEKA 251119 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 419 AM PDT Thu Apr 25 2024 .SYNOPSIS...A cold front will bring cooler temperatures and periods of light rain to mainly Del Norte and Humboldt counties today through Friday. A few showers will make it farther south and east. For the weekend and into next week mainly dry and cool conditions are expected. There may be some frost on the colder mornings. Some light rain is possible on Wednesday. && .DISCUSSION...The satellite shows a cold front approaching the west coast. Most of the energy is expected to remain north of the area with only some light rain making it down into northwest California. Rain in Del Norte county is expected to start around 8 or 9am and an hour or two later around Humboldt Bay. Southern Humboldt is expected to see a sharp gradient in the precip amounts and this will increase the uncertainty as a small shift could easily bring a change to the outcome. Snow levels may drop down to 5,000 feet at times, but snow accumulations will be fairly light. A few light showers are possible in northern Mendocino county and western Trinity county. Southern Mendocino and Lake counties are generally expected to stay dry with just a few sprinkles possible. Highs will be in the 50s in most areas although southern Mendocino and Lake counties may get into the 60s. Tonight with widespread cloud cover around temperatures are expected to mainly be in the 40s. Friday continued showers are expected. Mendocino and Lake counties may see a few more showers, but amounts are still generally expected to be less than a tenth of an inch. Northerly winds are expected to increase Friday afternoon and evening in Mendocino and Lake counties. The NBM is showing a 10 to 20 percent chance of wind gusts over 40 mph in the mountains of Lake county. Friday night into Saturday near freezing or freezing temperatures are possible in most valleys. Mendocino, Lake, and Trinity counties are the most likely to see frost in the colder valleys as they are expected to see less rain. This will be dependent on how much rain falls and how much fog forms. Currently the NBM model is showing 80 to 100 percent chance of low temperatures dropping into the low 30s in northern Mendocino and Trinity counties. Sunday through Tuesday nearly zonal flow is expected to keep temperatures below normal, although it generally looks dry at this time. The coastal counties will generally see quite a bit of cloud cover around and this will limit the potential for frost, but if skies do manage to clear out it is certainly possible. Areas farther inland are more likely to remain clear and see freezing temperatures. The best chances will be in Trinity county, but eastern Mendocino and Lake county will still have a 20 to 30 percent chance of seeing frost. Wednesday and Thursday some of the models are showing another weather system bringing some rain, but at this point there is still a lot of uncertainty on amounts and timing. Probabilities of a tenth of an inch rain range from 65 percent near the Oregon border to 10 percent in southern Lake county. MKK && .AVIATION...Stratus remains in place across much of the area and CIGS vary from IFR to MVFR at the TAF sites. A cold front approaching the coast today is expected to help mix out this stratus and lift CIGS this morning. Late this morning and into the afternoon rain is expected to move into KACV and KCEC. This is expected to bring lower CIGS, although the rain looks light and it make take some time for them to lower. Winds are out of the south in the north, but are light this morning. These winds will pick up this afternoon and winds of 10 to 20 kt are possible at KACV and KCEC. Ukiah will continue to see northerly winds which may increase to 10 kt. IFR ceilings are expected again tonight with the zonal flow and periods of light rain. This will start to break up towards morning and MVFR conditions are more likely on Friday. MKK && .MARINE...Stronger breezes and square to steep wind waves have been reported this morning, near Point Arena. Borderline small craft advisory criteria will ease by day break as winds diminish to a light to gentle breeze. A pressure diffluence will split the wind profile, WNW south of Shelter Cove and southerly winds north of Cape Mendocino. This transition will continue to shift towards the south as an upper level trough approaches the northern area waters this evening, bringing tighter pressure gradients and a series of weak cold fronts. Response to these conditions will manifest into Small Craft criteria by Friday night and into Saturday. An SC.Y has been hoisted to cover these conditions in the southern inner and outer waters. Otherwise, the ongoing WNW swell at 10 - 11 seconds will gradually ease below 10 seconds with wave heights around 6 - 7 feet through Saturday. A longer period W swell will arrive Saturday morning around 14 seconds with smaller wave heights around 2 - 3 feet. Monday evening looks to have near Gale gusts south of Cape Mendocino which will last through Tuesday evening. /EYS && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... None. && $$ 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