textproduct: Eureka

AVIATION 00Z UPDATE

Coastal stratus remains this afternoon with its reach ebbing and flowing over coastal terminals. High resolution models suggest a fairly narrow strip may remain for the coast tonight, yet offshore wind in Del Norte County could keep the layer away from KCEC if the marine layer remains deep. Areas under the stratus can expect IFR to LIFR conditions along the coast and within coastal river valleys. Some models are suggesting that southerly winds could form within the Russian River Valley, pushing stratus over KUKI, yet confidence is low on these winds forming within the valley, leaving a SCT group at this point. The marine layer is expected to mix and move slightly offshore, away from terminals tomorrow by around 17Z (+/- 1hr).

PREV DISCUSSION

/issued 252 PM PDT Sun Aug 16 2026/

KEY MESSAGES... * Smoke remains over areas outside of the marine layer due to local and distant wildfires.

* Interior temperatures are expected to remain near normal through through first half of the week with highs in the low to mid 90s.

* Another trough is expected to bring below normal temperatures and the potential for a few thunderstorms late in the week.

SYNOPSIS...A series of upper level troughs off the west coast is expected to generally keep inland temperatures near normal in the 90s. This will also keep persistent marine clouds along the coast with some afternoon clearing. Late in the week a stronger trough will bring cooler inland temperatures and the potential for inland thunderstorms.

DISCUSSION...A very brief shortwave ridge is building over NW CA today. This is bringing a slight warmup in the interior areas and helping to clear out the coast. Temperatures in many areas are running 5 to 10 degrees warmer than yesterday. Some high clouds have started to move over the area and this may slow the warming. There is some offshore flow in Del Norte county and this may keep the coastal clear for a few hours into the evening. Monday another trough approaches from the southwest. Temperatures are expected to be similar to today. Some high clouds are expected to move over the area in the afternoon. In the afternoon there is instability, but it doesn't look like there will be enough moisture for any thunderstorms. The CAMS aren't showing any storms in the area and the NBM thunder probs are only around 5 percent. Still this trough has been producing some lighting from time to time off the coast. So this will definitely need to be watched as it gets closer, but for now will keep thunderstorms out of the forecast.

Tuesday the ridge builds back to the west and continues to bring high temperatures in the mid 90s. Coastal clouds may see a few breaks in the afternoon, but are generally expected to be pretty persistent. Wednesday the next trough starts to push the ridge to the east, but conditions generally persist. The stratus as the coast may be slightly more stubborn and linger through the afternoon.

Thursday and Friday the next upper level trough is expected to move by the area. A couple of the model clusters showing the vorticity lining up with the afternoon heating on Friday. However there is a lot of uncertainty in how much moisture and instability there will be. This will need to monitored as it gets closer. MKK

MARINE...Northerly wind are in place across the waters this afternoon and these are expected to increase in the outer waters overnight. These look to increase to around 20 to 25 kt so have expanded the small craft advisory to the southern outer waters. Closer to the coast the models are showing the local southerly winds returning again this evening. This currently has northerly winds waves around 3 to 4 feet and these are expected to increase overnight. Also, a southerly swell is also moving through the waters this afternoon. Currently the Cape Mendocino buoy is showing it around 3 feet at 17 seconds.

Monday the northerly winds are expected to diminish through the day as a shortwave moves by the area so have the small craft advisory ending during the day. The southerly swell is expected to continue at around 3 feet at 14 seconds. Tuesday and Wednesday as high pressure briefly builds in northerly winds are expected to increase to around 20 to 25 kt. Thursday and Friday the next trough is expected to arrive and winds are expected to diminish again with the potential for local southerly winds near the coast. MKK

Fire Weather...The main challenge for the fire weather forecast is the potential for thunderstorms. Monday afternoon a shortwave moves through, but at this point it doesn't look like it things will line up for any thunderstorms. There may be some increased instability, but not enough moisture for any thunder. Tuesday through early Thursday weak high pressure is expected to bring dry and fairly stable conditions. Thursday night or Friday another trough is expected to approach the area. At this point it is still hard to tell if the moisture instability and lift will line up to get thunderstorms, but it is possible. This will need to be watched as it gets closer. MKK

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory from 9 PM this evening to 9 PM PDT Monday for PZZ470.

Small Craft Advisory from 9 PM this evening to 9 AM PDT Monday for PZZ475.