Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
232 FXUS66 KEKA 292258 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 358 PM PDT Sun Sep 29 2024 .SYNOPSIS...Dry and warming trend is expected mid week, with interior hot temperatures by midweek. Breezy northwesterly winds along the coast through this evening, with gusty offshore flow over the interior ridges through Tuesday. Dry and above normal temperature is expected to persist through the forecast period. && .DISCUSSION...High pressure has begun to builds into the Pacific Northwest and Northern California downstream from the trough moving into the Northern Rockies. Breezy northwesterly winds have developed over northern the coastal headlands in the wake of the trough, with northeasterlies over interior Del Norte. Gusty offshore flow from 25 to 40 mph will developed over the higher terrain in Del Norte and far northeastern Humboldt this evening and tonight. This offshore flow will bring an increasingly dry air across the area (see the Fire Weather Section for more details). The upper level heights will rises across the region Monday through Tuesday, and a warm deep- layer air-mass will develop across the WRN CONUS. Model guidance has been very consistent supporting 850 mb temperatures of 25-28C or so over much of the interior. Interior heat will build on Monday and then peak on Tuesday. High temperatures in the hottest valleys are expected to range from 97- 110F degrees. The heat risk is forecast to be moderate over the area, but a major heat risk is expected to occur over portions of interior Mendocino and Lake counties on Tuesday and Wednesday. The heat will have impacts on some individuals sensitive to heat, especially those without effective cooling and/or adequate hydration. A Heat Advisory is now in effect from 11AM Tuesday through 11 PM PDT Wednesday for interior Mendocino and Lake counties. Meanwhile, thermal troughing will shift offshore heading into Tuesday, allowing for coastal areas to even heat up well and reach the 70s, with adjacent coastal areas reaching the low 80`s on Tuesday as the usual afternoon onshore breezes should be held back. Wednesday, the high pressure weaken and "flatten" as an upper level trough moves across the Pacific Northwest. This will promote some high clouds streaming across the area. Temperatures are expect to decrease few degrees, although will remain pretty similar lake Tuesday across the interior valleys. Breezy to locally windy conditions are expected every day through Thursday, with overnight offshore flow. The ridge aloft will shift eastward late in the week, with an upstream upper level trough approaching the area. Cluster analysis are not in a good agreement with the timing and location of this trough, with large discrepancies in the features of this feature. Models continues to differ with the progression of this system. && .AVIATION...Stratus enveloped the Humboldt and Del Norte coasts around sunrise. A building ridge continues to produce strong northeasterly winds aloft creating LLWS for the North Coast. While this occurs strong north to northwesterly winds will continue to impact coastal terminals. Between stronger northerly winds at the surface and persistent offshore flow aloft, particularly in Del Norte County, stratus may have a difficult time forming tonight and into tomorrow morning. However, some areas of the coast could form some stratus into tomorrow morning. Other interior terminals are expected to maintain VFR conditions through the TAF period. && .MARINE...Northerly winds continue to ramp up this afternoon with gale force gusts of 40 to 45 kts expected in the outer waters through Monday. Significant wave heights will increase in response, from 8-11 ft today to 12-14 ft hazardous seas Monday. Winds possibly subside by Thursday. Seas will stay elevated Wednesday and Thursday as a mid-period westerly swell combines with steep wind waves. Seas are forecast to finally dip below 10 ft Friday. && .FIRE WEATHER...Red Flag Warning is in effect for zones 203 and 204 from 8PM this evening through 11AM Tuesday. Low daytime humidity values from 10 to 25 percent are occurring across the interior this afternoon. Breezy offshore flow will to increase over the higher terrain in Del Norte and northeastern Humboldt late this afternoon and evening. Expect gusts from 25 to 35 mph this evening and tonight, with locally strongest gusts. Additionally, northeast winds of 10 to 20 mph will developed tonight into Monday for some of the ridgetops of eastern Lake County, accompanied by poor overnight humidity recoveries. A headline remain for zone 264 due elevated fire weather threat. Drier offshore flow will promote poor RH`s recoveries through the work week, with very poor recoveries Tuesday and Wednesday morning. Hot temperatures from 97 to 110F, very poor humidity and breezy offshore flow will promote locally critical fire weather conditions through Wednesday, with elevated conditions remaining into the weekend. && .EKA WATCHES/WARNINGS/ADVISORIES... CA... Red Flag Warning from 8 PM this evening to 11 AM PDT Tuesday for CAZ203-204. Heat Advisory from 11 AM Tuesday to 8 PM PDT Wednesday for CAZ110-111-113>115. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 3 PM PDT Monday for PZZ450. Small Craft Advisory until 9 AM PDT Monday for PZZ455. Gale Warning until 3 PM PDT Monday 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