textproduct: Eureka

KEY MESSAGES

* Deep marine influence near shore will persist but slowly weaken through Wednesday.

* Generally seasonable temperatures across the interior with isolated, weak showers possible for the eastern interior Wednesday.

* A dry cold front late week. Very high uncertainty by the weekend with equal chances for moderate rain or warm and dry weather.

SYNOPSIS

Deep marine influence will persist near shore through Wednesday with seasonably cool conditions for the interior. A dry cold front will pass late in the week.

DISCUSSION

Low pressure currently stalled offshore of the PNW will gradually meander south over the next few days. Today, the low has helped push a deep marine layer far inland alongside thick midlevel clouds. This combination has helped keep conditions much more cool and moist not just near shore but all across the interior. Event he warmest inland valleys have stayed below 70.

The low will meander south but largely remain offshore through Wednesday. Light offshore wind on the north side of the low will help push marine air out of interior valleys. Still, midlevel cloud cover and a still elevated marine layer will keep the shore cool and grey. Slight coastal drizzle is possible as the low passes by the coast early Tuesday morning. The interior will warm only slightly, generally into the mid 70s during the day.

Some high resolution models show the low pushing moisture up the Sacramento Valley around Wednesday, forming showers in Eastern Trinity and Mendocino Counties. This solution is relatively unlikely with the broader ensemble suite only show a 10% chance of weak showers. In any case, midlevel clouds are likely that day.

Most ensemble members show a weak cold front dipping across the area around Thursday and into Friday. This front would be most dry lifting but also eroding the marine layer. Potential with any rain along this front is minimal (less than 10%). Cool and dry conditions immediately behind the front will likely aid in dry but cold interior conditions with widespread possible frost Friday morning.

By the weekend, ensembles models show a remarkable amount of d divergence. Roughly 50% show a strong, moist low dipping across the area with potential for 1-2 inches of rain along the North Coast. The other 50% show high pressure building generating warmer and drier than normal conditions. This makes the deterministic official forecast unusually uncertain for anytime beyond Friday. /JHW

MARINE

Generally gentle north winds will persist through Wednesday with some weak southerly winds in the inner waters. Weak winds will keep short period seas calm, but a mid period swell will quickly build up to 12 feet Tuesday, generating some marginally steep seas during the day. The swell will mostly decay below 8 feet by early Wednesday. Moderate north winds will gradually build in the outer waters Thursday. Winds will push closer to shore Friday as cold front passed by with some near gale gusts likely by Friday in the lee of Cape Mendocino. /JHW

FIRE WEATHER

A deep marine layer sweeping far inland has created much more cool and moist conditions Monday. Winds turning back offshore Tuesday and Wednesday will help regenerate moderately dry conditions, but even then RH recovery will remain high with daytime RH struggling to get below 30 percent. High temperatures will broadly remain in the 70s. Another cold front late int he week will most likely lift marine air back over the interior Thursday, though chance of wetting rain is near 0%. Cold dry air Friday will help bring RH back closer to 20 percent during the day. Aside form some moderate winds along the front Thursday, winds will be weak. The forecast is highly uncertain by the weekend with equal chances of moderate rain and unseasonably warm and dry conditions. /JHW

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory from midnight tonight to 8 PM PDT Tuesday for PZZ450-455.

Small Craft Advisory from 11 PM this evening to 8 PM PDT Tuesday for PZZ470-475.