Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
056 FXUS66 KEKA 241044 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 344 AM PDT Mon Jun 24 2024 .SYNOPSIS...Interior warm and dry conditions continue through Tuesday while marine stratus dampens coastal temperatures. An upper level disturbance mid-week will allow for relatively cooler temperatures through Thursday. Warming trend returns for this weekend into next week. && .DISCUSSION...Coastal stratus is slowly beginning to expand beyond the Eel River Delta/Humboldt Bay area this morning beneath a shallow marine inversion. HREF still has a strong signature indicative of thickening stratus extending up to the Del Norte and Southern Mendocino coasts after 6 am, although ceilings will likely be limited to around 1000-1500 feet. Surface wind gust probabilities significantly reduced today as the coastal pressure gradient begins to diminish. HREF only indicating 15-25 mph gusts on coastal headlands (Point Saint George, Cape Mendo and Pt Arena) while lee coasts are slightly shielded. Once again, coastal highs will remain dampened by marine stratus redevelopment while hot temperatures are forecast for the interior. NBM probabilities are favoring highs in the low to mid 90`s and approaching/reaching 95-98 degrees again in the valleys of Southern Mendocino, Lake and eastern Trinity counties - slightly reduced a few degrees compared to this weekend. This pattern is expected to remain largely consistent through Tuesday with daily surges in diurnally driven NW flow. Echoing the previous discussion, both GFS and NAM continue to highlight a SE surge of mid-level subtropical moisture in 500-700 RH analysis beginning early Tuesday morning. NAM model soundings show 100-300 J/KG MU Cape, aligning with weak signatures of hi-res ARW simulated reflectivity in SE Mendocino and Lake counties by early afternoon. Confidence is still quite low regarding the potential for dry lightning, especially with weak lift and only marginal instability, but this timeframe will be monitored closely over the next 12-24 hours. Otherwise, a pattern change is still expected early Wednesday into Thursday as an upper level trough drops into the PNW, inducing relative cooling of temperatures and slightly elevated westerly winds. NBM probabilities drop off significantly in the upper 80`s and low 90`s for the interior valleys, especially on Thursday following a weak frontal passage. This bit of lift will likely be sufficient to reduce coastal stratus in the latter half of the week. 500 mb clusters are beginning to align in favor of relatively zonal flow turning over to broad ridging late next weekend for another warming trend. && .AVIATION...IFR stratus has developed overnight in the Humboldt Bay area and up the Eel River Delta early this morning, with wisps drifting northward toward Del Norte at time of writing. Fog is expected to mix out by mid-morning, with VFR expected this afternoon for most of the coast. More expansive IFR ceilings will most likely start to return late this evening, although visibilities are expected to remain decent tonight. Otherwise, widespread VFR conditions will persist for the interior with normal summer conditions. && .MARINE...Northerly winds persist this morning, then weaken this afternoon, and by this evening only the southern waters are forecasted to support short period seas steep enough for a small craft advisory. Meanwhile a minor northwest swell of 5 feet at 11 seconds will persist through the day today then decay Tuesday. Northerlies are forecast to remain below 15 kt for most zones during Tuesday through Thursday morning, aside from the persistent 15-20 kt northerlies expected directly downwind of Cape Mendo. Winds may strengthen again Thursday afternoon into this weekend. && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 3 PM PDT this afternoon for PZZ450-455-470. Small Craft Advisory until 9 AM PDT Tuesday for PZZ475. && $$ 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