Area Forecast Discussion

KEY MESSAGES

- Temperatures will warm quickly with moderate to major HeatRisk expected Thursday through the weekend and into early next week.

- A more widespread return of coastal stratus is expected tonight south of Cape Mendocino and continues to expand over the weekend. - Potential cooling trend in the inland areas starting on Wednesday. .SYNOPSIS...High pressure continues to build into the area with hot temperatures expected into early next week. The near coastal and coastal areas may start to see more marine influence over the weekend and into early next week while Trinity county is expected to see the hottest temperatures Monday and Tuesday. Cooler temperatures are possible starting on Wednesday.

DISCUSSION

High pressure continues to build in across the area and the interior is expected to see one of the first hot days of this heatwave. A few marine clouds returned along Humboldt coast this morning but clear out by mid to late morning. It looks like this will occur again Friday morning, although confidence is low on this. A southerly surge of clouds is making it's way north into Monterey Bay this afternoon. This is expected to make it's way north overnight and may reach the Mendocino by some point on Friday. This will likely start to cool temperatures at the immediate coast and inland to areas as far as Boonville or so. Overnight lows will likely drop into the 50s in most of the valleys, however the ridges are expected to stay much warmer, likely in the 70s. This will increase the heat risk in these areas.

For the weekend a weak upper level trough is expected to drop down from the north. This is expected to bring some instability, but current moisture profiles look like they remain too dry for any thunderstorms. Temperatures are expected to remain more steady fluctuating somewhere around 100 in the afternoons. The winds southerly winds along the Mendocino coast are expected to slightly increase and keep the stratus in place. The high pressure is expected to keep the marine layer fairly shallow and it may mix out each afternoon. Sunday it looks fairly certain that the marine layer will be well north of Cape Mendocino as the winds get lighter. Monday and Tuesday high pressure continues to the strengthen over the area and is expected to some of the hottest temperatures of this heat wave to Trinity county. Areas closer to the coast there is more uncertainty and this will need to be monitored as it gets closer.

Wednesday the high pressure is expected to start to break down and cooler temperatures are expected aloft. This will cool temperatures across the area and likely deepen the marine layer. MKK

AVIATION.

VFR conditions took firm hold after the remnant, shallow stratus around Humboldt Bay dissolved through late morning. Northwesterly winds will be breezy through the afternoon at the coastal terminals. Wind gust over 20 kts at ACV and up to 30 kts at CEC through the afternoon will ease into the evening. Similarly to this morning, stratus should develop around Humboldt Bay and work into the coastal terminals around or after 14Z. What does manage to form will quickly scatter out near or after 16Z Friday. Northwesterly winds will turn breezy again Friday afternoon.

MARINE

Gale strength northerlies persist through the outer zones through Saturday. The southern outer zone will have less coverage Friday, mainly around Cape Mendocino and westward. Northerly winds and steep seas will continue advisory conditions for the inner zones. Strengthening northerlies over the northern outer waters Friday will build steep and hazardous seas up to 14 ft. The northern inner waters will have to be watched for a brief surge of hazardous seas late Friday. Currently it looks like the gales will continue beyond 10 to 20 nm north of Cape Mendocino on Saturday, then start to diminish on Sunday and this allows a southerly surge to move northward. Winds are generally expected to remain lighter into early next week.

FIRE WEATHER

Temperatures are expected to remain hot and dry into early next. Over the weekend a shortwave moving down form the Pacific Northwest is expected to increase instability and this may lead to increased mixing heights. It doesn't look like there will be enough moisture in NW California for any thunderstorms, that is expected to remain well east and south of the area. Early next week temperatures may climb slightly more and the hottest temperatures of the heat wave are expected. Wednesday into late in the week cooler temperatures are expected. This may also bring stronger winds or possibly thunderstorms depending on how the pattern evolves. MKK

EKA WATCHES / WARNINGS / ADVISORIES

CA... Heat Advisory until 10 PM PDT Friday for CAZ113-114-118>120.

Red Flag Warning until 5 PM PDT this afternoon for CAZ419.

NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 8 PM PDT this evening for PZZ450.

Small Craft Advisory until 9 AM PDT Friday for PZZ455.

Gale Warning until 9 PM PDT Saturday for PZZ470.

Gale Warning until 9 AM PDT Friday for PZZ475.