Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
877 FXUS66 KEKA 052213 CCA AFDEKA AREA FORECAST DISCUSSION...CORRECTED National Weather Service Eureka CA 313 PM PDT Sun May 5 2024 .SYNOPSIS...Light rainfall will develop Monday with a weak front. Building high pressure will increase northerly winds on Tuesday as a significant warming begins that will span through late next week. && .DISCUSSION...Shower activity has eased with exception for a few 30 - 40 decibel radar reflectivity returns, north of Cape Mendocino. The cold upper level trough continues to transition towards the southwest although it looks to be weakening with isobars appearing diffuse and considerable warming in the four corners region. Local effects from a more zonal flow pattern will be experienced with a weak cold front coming through tomorrow and stronger winds to follow Tuesday afternoon. Large scale ridging will follow as an area of high pressure dominates the E. Pacific. This synoptic ridging and zonal flow will bring high winds to bear on the West Coast. The probability of sustained winds reaching over 30 mph is 85 - 90%, just off the coast of our CWA and south of Cape Mendocino. Wednesday we will see an expansion of high winds reaching into the Oregon waters while some higher elevations and headlands may get exposure. Winds will also increase over the higher terrain of Eastern Lake County Tuesday night through Wednesday. As the ridge continues to amplify, an upper trough looks to retrograde west into the Great Great Basin. This setup would be favorable to generate offshore flow and further enhance the warming temperatures late next week. Probabilities have been consistently high (80 to 90%) for the inland valleys to exceed 80 degrees, and 50 to 75% chance to exceed 85 degrees in the warmest interior valleys late next week. Otherwise, below average temperatures remain in the wake of the low, though inland valley fog and lingering cloud cover will hold up the temperatures for some local areas. Clearing in Trinity County and southward will allow for freezing to frost conditions tonight, thus Freeze Watches and Frost Advisories are out. A weak frontal system will clip the region on Monday, bringing light rainfall over mainly Del Norte County where 0.25 to 0.5 inch is forecast. Much lighter values can be expected down to Trinity and Humboldt counties, while Lake and Mendocino counties will begin to experience warmer daytime temperatures. && .Aviation...Aside from perhaps some locally gusty wind from isolated showers this afternoon, the main problem will be lowering ceilings along the coastal terminals by 12-14Z Monday. Ensembles indicate that by 12Z, coastal terminals stand at least a 30-50% chance of lowering to MVFR ceilings, with chances steeply rising, with KCEC a bit ahead of the curve compared to KACV by a couple of hours as the next weather system moves in. As for wind gusts at KUKI, ensembles indicate that this should be at its peak near 23Z today, generally decreasing overnight into Monday. Ensembles also indicate timing of light precipitation to begin near 14-15Z for coastal terminals, with higher gusts near any convective showers, with rain not likely reaching KUKI. && .Marine...Buoy observations have been over performing the forecast wave heights by a foot or two for the past couple of hours, producing waves steep enough for small craft advisories. Latest trends of buoys indicate that this may only be temporary and heights will be coming down to near 6 feet soon. This will need to be monitored in case small craft advisories for tonight need to start earlier. A northwest swell is prominent. Winds have/will become generally westerly today then turn southerly Monday in advance of an approaching cold front, as it moves east through the waters. By Tuesday, ridging will build over the west coast, allowing surface high pressure to strengthen off the coast. Northerly winds will increase with gales likely beginning as early as Tuesday/Tuesday night. Waves will become very steep as the winds ramp up. A gale watch looks like a good bet, especially for outer waters for Tuesday night into Wednesday night. Combined wave heights top 10 feet by Tuesday night as well and increase into Wednesday and Wednesday night. && .EKA WATCHES/WARNINGS/ADVISORIES... CA... Freeze Watch from 1 AM PDT Monday through Monday morning for CAZ107-108. Frost Advisory from 1 AM to 9 AM PDT Monday for CAZ110-111- 113-115. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory from 5 AM to noon PDT Monday for PZZ450. Gale Watch from Tuesday afternoon through late Wednesday night for PZZ450-455-470-475. Small Craft Advisory from 1 AM to noon PDT Monday 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