textproduct: Eureka

KEY MESSAGES

- Northerly breezes near the coastline through the weekend.

- Hotter temperatures over the holiday weekend.

SYNOPSIS

Northerly breezes will persist along the coastline through the weekend into the first half of next week. Temperatures will begin to warm on Friday, peaking over the weekend, with interior valley high temperatures in the mid to high 90s.

DISCUSSION

A ridge will begin to build over the inter-mountain west this weekend. 850 mb temperatures will warm over Northwest California allowing temperatures to heat into the mid to upper 90s, locally 100 degrees, across interior areas this weekend. Despite the building ridge, a weak shortwave will move overhead Monday into Tuesday, bringing slightly cooler temperatures aloft increasing the potential for higher instability. Guidance is producing light QPF over the higher terrain just north and east of the area. Model soundings indicate poor lapse rates in the mid-levels over Northwest California, which could be just enough to stop any convection from fulfilling its potential over Trinity or Mendocino counties.

A trough over British Columbia will move east-southeast early next week bringing slightly cooler air to the region, allowing interior temperatures to fall back into the upper 80s to the mid 90s during the first half of the week. There could be a slight increase in moisture ahead of the trough and depending on how far south the trough dives an isolated shower or two could develop Tuesday night into Wednesday with the best chances over the higher terrain.

Details specific to July 4th: Temperatures are forecast to be around 60 at the coast and in the lower to mid 90s inland. Cloud cover may be more extensive along the coastline with moisture increasing in the boundary layer and a stronger marine layer inversion due to the building ridge. Low stratus and fog may be a concern during the evening hours for coastal areas depending on the strength of the coastal winds and the mixing they can provide. With that said, the HRRR guidance does give some hope of offshore flow and drier air trying to mix into the marine layer in the afternoon. /RPA

AVIATION

More widespread cloud cover is evident along the coastline on visible satellite imagery and these clouds do not appear to be dissipating this afternoon as northerly winds decrease over the coastal waters. Thus, it is highly likely that IFR ceilings will develop at ACV and tonight spread north toward CEC. Already a few six hundred foot ceilings are being reported as of this writing. As winds continue to decrease on Friday, stratus will likely be more persistent and could last through much of the morning hours. Inland VFR is anticipated through the entire TAF period but light south winds in the valley around Ukiah may see a few clouds attempt to get past Hopland from the south in the early morning around daybreak. /RPA

MARINE

Winds have become lighter and all warnings have been downgraded to small craft advisories. Winds will continue to decrease overnight into Friday allowing small crafts to end in the inner waters tonight into Friday morning. Winds will remain moderate to strong in the outer waters for the next several days and the current expiration of the small craft for the outer waters zones Sunday morning will likely need to be extended further, especially south of Cape Mendocino. /RPA

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 9 PM PDT this evening for PZZ450.

Small Craft Advisory until 9 AM PDT Friday for PZZ455.

Small Craft Advisory until 3 AM PDT Sunday for PZZ470-475.