textproduct: Eureka

KEY MESSAGES

* Elevated fire danger Today in Trinity, Lake and NE Mendocino counties due to low RH and breezy winds.

* Near normal inland temperatures expected through next week.

* Night and morning coastal clouds with afternoon clearing.

SYNOPSIS

A persistent upper level trough north of the area will bring inland temperatures to near or slightly below normal while bringing slightly warmer than normal coastal temperatures. Breezy winds are expected each afternoon, especially over inland areas. This will increase fire danger in Trinity, Lake and NE Mendocino county with low afternoon RH. The coast is expected to continue to see night and morning coastal clouds.

DISCUSSION

An upper level low off the West Coast continues moving slowly north. It eventually will settle into the Pacific Northwest becoming the main driver of weather through early next week. The low will continue to bring near or slightly below normal inland high temperatures. At some areas of the coast, unusually warm temperatures with highs in the upper 60s could continue today, with most coastal areas returning to a more normal high temperature today and through the weekend. The last warm days at the coast, especially around Humboldt Bay, have been caused by southerly winds aloft downsloping and warming the air. These winds aloft look to turn slightly more southwesterly early this morning which could bring temperatures at the coast back closer to normal, but it is uncertain on how quickly this will happen. Winds at the surface are generally expected to be westerly. At the coast and near coastal areas, this will influence a deeper marine layer to develop which will also keep RHs from getting too low in the afternoon. Farther inland will see RH in the teens, especially today. For more details see the fire weather section. Any stratus that forms is expected to clear out by midday.

For the weekend and into early next week conditions are expected to remain fairly persistent with the trough to the north of us and a building ridge south of us. There is some uncertainty on how this will impact the marine layer, but it generally looks like it will remain deep. Most of the times this means the inversion will be weak and it will clear out fairly well each day, however confidence is low and there could be some subtle changes to this. MKK

AVIATION

A deeper marine layer is anticipated to develop very early this morning. MVFR to IFR ceilings will affect coastal terminals such as KCEC and KACV. Near coastal terminals could see stratus reach them before sunrise; however, stratus is not expected to by deep enough to make it to KUKI. Other inland terminals are expected to be VFR through the TAF period.

MARINE

Generally light winds will continue across the waters with a split flow pattern. North of Cape Mendocino is seeing light southerly winds while areas farther south are seeing northerly winds. These are all less than around 10 kt. There are several swells moving through the waters as well. There is a southerly swell around 3 feet at 15 seconds, a northwest swell around 2 feet at 9 seconds and then some 1 to 2 foot wind driven waves mainly in the southern waters. The swells are generally expected to remain fairly small. Today, a long period southerly swell is expected to start building in to around 2 feet at 21 seconds. If this comes in larger than expected it could lead to a sneaker wave threat.

This general pattern is expected to continue through Saturday. Sunday and into next week northerly winds start to gradually increase, but only to around 10 to 20 kt by early next week.

FIRE WEATHER

General onshore flow and a trough to the northwest of the area will keep RH higher and temperatures lower closer to the coast. However, this trough will also bring breezy northwest winds to much of the area. Areas farther away from the coast are expected to see lower afternoon RH and moderate recoveries overnight. This is expected to increase fire danger in Trinity, Lake and NE Mendocino counties especially Today. These areas are expected to see RH drop into the teens Today and see wind gusts in the afternoon of 20 to 25 mph. Saturday the afternoon RH is expected to increase slightly with similar winds. This pattern is generally expected to continue into next week with only slight fluctuations on the RH and wind. MKK

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... None.