textproduct: Eureka

SYNOPSIS

Dry conditions will persist through the weekend. A slight chance of rain for Monday and Tuesday with better chances for widespread rain over the region Tuesday night through Friday.

DISCUSSION

Northwest California will remain wedged between a building upper-lvl ridge over the desert southwest and a developing upper-lvl trough in the Gulf of Alaska through this weekend. Gradually, the upper level ridge will move eastward allowing the trough and its associated polar maritime air to flow over our area. This change in large-scale weather systems will be experienced by cooler temperatures much closer to normal beginning early next week. Increased moisture will also flow over the region, leading to overnight lows remaining warm. With that said, tonight should be the last night of frost formation in areas where the growing season has already begun. Thus, one last frost advisory has been issued for northern interior Mendocino County Saturday morning.

The aforementioned moisture from this maritime air will increase chances for rain next week. The trough that will flow over NW CA will initiate a 20-40% chance of rain showers Monday and Tuesday, with the highest chances over the interior as afternoon heating forces the relatively weak convection. The rain totals for early next week have decreased. This change seems to be due to global models resolving the center of this surface low pressure system over interior British Columbia early next week instead of the previous center being over the PacNW.

A more potent frontal is likely to approach the area Tuesday night into Wednesday with the potential for gusty ridge line winds and a quick burst of moderate to heavy precipitation. Overall, rainfall is expected to be generally beneficial to the region and impacts should be minimal. However, depending on the rain rates, isolated flooding of poor drainage areas could occur. Additionally, this second system on Wednesday is forecasted to be colder than the system arriving Monday as snow levels drop to below 5000 feet on Wednesday and down to 3500 feet for northern areas by Thursday morning. Light accumulating snow is possible as showers linger into Thursday and enough snow over 5000 feet in northern Trinity County could necessitate a winter weather advisory for Scott Mountain Pass.

AVIATION...(28/06Z TAFs)

Low clouds have been developing around the Humboldt Bay and along the Eel river valley. This is promoting MVFR with low clouds around 900 feet in ACV. Meanwhile VFR conditions prevail in CEC. Meanwhile, VFR conditions prevail at CEC, with high-level clouds streaming across the area. However, there is a 10-15% chances for LIFR visibility reduction in mist or shallow fog between 10Z-15Z Saturday for both coastal terminals. Any low clouds and/or mist is expected to lift and clear out after 15Z, followed by VFR conditions. Light E winds to very light and variable overnight, becoming NW at 5-10 kts after 17Z. Meanwhile, prevailing VFR along with very light and variable winds at UKI. /ZVS

MARINE

Moderate to fresh northerly winds will continue to slowly diminish through the weekend across the waters as an area of low pressure develops off the coast and the pressure gradient relaxes. Steep, short period seas will continue to subside and eventually for all headlines to expire for a brief period Sunday.

Northerly winds are expected to increase again in the wake of a weak front Sunday night into Monday, with strong breezes over the outer waters and promoting hazardous conditions for small crafts. The next chance for strong winds will be mid next week as a stronger frontal system moves into the region and bring an increasing chance for strong to near-gale southerly winds. /ZVS

EKA WATCHES/WARNINGS/ADVISORIES

CA... Frost Advisory from 4 AM to 9 AM PDT this morning for CAZ110-111.

NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 6 AM PDT early this morning for PZZ450-455.

Small Craft Advisory until 6 AM PDT Sunday for PZZ470-475.