Cape Mendocino to Point Arena CA from 10 NM to 60 NM Marine Forecast
|Tonight...N Winds 5 To 10 Kt. Waves Nw 3 Ft At 8 Seconds...And S 4 Ft At 17 Seconds. Patchy Fog.|
|Wed...N Winds 5 To 10 Kt. Waves N 4 Ft At 7 Seconds...And S 4 Ft At 16 Seconds. Patchy Fog.|
|Wed Night...N Winds 5 To 15 Kt. Waves N 5 Ft At 5 Seconds... And S 3 Ft At 16 Seconds. Patchy Fog.|
|Thu...N Winds 5 To 15 Kt. Waves N 5 Ft At 5 Seconds...And S 3 Ft At 15 Seconds.|
|Thu Night...N Winds 10 To 15 Kt. Waves N 6 Ft At 7 Seconds... And S 2 Ft At 15 Seconds.|
|Fri...N Winds 10 To 15 Kt. Waves N 7 Ft At 7 Seconds...And Nw 4 Ft At 13 Seconds.|
|Sat...Nw Winds 10 To 20 Kt. Waves N 6 Ft At 6 Seconds...And W 4 Ft At 12 Seconds.|
|Sun...Nw Winds 10 To 15 Kt. Waves Nw 6 Ft At 6 Seconds...And W 3 Ft At 12 Seconds.|
| Area Forecast Discussion|
National Weather Service Eureka CA
257pm PDT Tuesday Jun 22 2021
An upper level low drifting around offshore will keep temperatures slightly below late June averages across the interior through midweek. This low will also bring a slight chance of thunderstorms each afternoon in the interior through Thursday. Coastal areas will remain cool with areas of marine layer clouds. Another heat wave is in store for the interior this weekend, possibly persisting through the early portion of next week.
Primary concern for the next 3 to 4 days will be the potential for interior convection each afternoon. Some cumulus clouds have been building this afternoon, but quickly collapsing in the dry and stable environment. Soundings continue to indicate too much convective inhibition for thunderstorms over most of the forecast area this evening. SREF and HREF thunder probabilities indicate very low chances for lightning activity, 5-10%, near the Siskiyou County Border this evening. Better chances are expected for the interior Wednesday afternoon and evening, with CAPE around 200-400J/kg and equilibrium level approaching 24kft. The threat for more lighting will increase on Thursday, with higher CAPE, PWATs (Precipitable Waters) and steeper lapse rates. SREF calibrated lightning probabilities of 100 cloud-to-ground lightning strikes or more increase to 2.5 to 4% on Thu. Thursday may end up being the most active day for lightning. Friday is still very uncertain with the potential for warmer air aloft and strong capping building over the area from the north. For now will hold off on adding storms for Friday, even though the GFS continues to the indicate easterly flow aloft and possible wrap around moisture on Friday.
ENS and GEFS means continue to show a massive 500mb height anomaly extending over the Pacific NW toward the latter portion of the week and over the weekend. All 500mb ensemble clusters show this pattern to one extent or another, with the possibility for weak cut-off low meandering nearby the forecast area through at least the early portion of the weekend. Deterministic model have 850MB temperatures climbing to 30C or more by Sunday. ENS and GEFS probabilities for 850mb temperatures of 25C or more increase over the weekend as well. Widespread triple digit heat is likely again for many of the interior valleys. Looking at the National Blend of Models, the strongest warming appears to occur in the northern most portion of the forecast area, at least initially, as the warm anomaly over the Pacific NW extends southward and a thermal trough builds along the coast. Mid spreads are bit tighter for cities such as Hoopa and Weaverville on Friday and Saturday, however there is still about 10F degrees of mid spread on Sunday which will likely be the hottest day. A few hotter valley spots could hit 108 to 112F again this weekend, especially in the narrow valleys and canyons of Trinity County. High heat risk is expected for the valleys by Sunday. This latest heat may persist into the early portion of the weak, though ensemble guidance indicates another upstream trough driving into a strong downstream ridge. This seems unlikely based on climatology and the persistence of the ridge.
Relatively light winds will persist across all waters through this evening, keeping any short-period waves to a couple feet or less. Northerly winds are expected to gradually increase to a moderate breeze on Wednesday, with winds continuing to increase to fresh breezes across parts the outer waters Thursday through Saturday.
A southerly swell of 3 ft at 18 seconds will continue to impact the area through the weekend. A northwesterly swell of 2 to 4 ft has arrived today and will sporadically persist through the weekend. Short-period northerly seas in the outer waters will build to 6 to 8 ft Thursday evening into the weekend in response to the increasing winds.
The main concern will be the potential for thunderstorm activity over the next few afternoons. The most likely scenario is for limited or isolated thunderstorm activity Wednesday or Thursday. As of 1430 today only some light cumulus has been observed over the Yolla Bollys and Trinity Mountains with much better development over Siskiyou County and northward. Will continue to utilize headlines in the planning forecast (FWF) through Thursday but now with the Low Pressure system remaining quasi- stationary through Friday we may have to extend those headlines one more day. Nonetheless...still do not anticipate any watches or warnings. That said, fuels are beginning to reach critical thresholds over portions of eastern Mendocino and Trinity County (and continue to be so around Lake County)...and with the next heat wave gearing up toward the end of this week those fuels will continue to dry out rapidly.
.EKA WATCHES/WARNINGS/ADVISORIES... CA...None. NORTHWEST CALIFORNIA COASTAL WATERS...None.