textproduct: Eureka

KEY MESSAGES

* Thick smoke remains stuck around the Hoopa Valley stretching from as far north as to Orleans as far south as the middle Eel River Valley. Weak transport winds will keep smoke here through the week.

* Interior temperatures peaking Tuesday will ease through the week with persistent marine influence along shore.

* Another trough is expected to bring below normal temperatures and very slight potential for a isolated thunderstorms Friday.

SYNOPSIS

Warm temperatures will ease through the week tanks to increasing marine influence. Marine clouds will persistent along shore with some slightly better clearing chances late week.

DISCUSSION

High pressure has peaked across the area today, allowing many interior locations to reach into the upper 90s. Besides a thin and slow to recede marine layer near shore, clear skies and gentle west winds have persisted. Smoke has continued to sock in valleys around the MP18 fire in Hoopa with smoke pushing up the Trinity River with afternoon terrain winds.

An elongated trough will gradually approach shore through the end of the week. This will help push marine influence further inland and weaken high pressure, allowing interior highs to pull back into the upper 80s by late in the week. Increasing marine influence will most likely help strengthen and deepen the marine layer along shore, a deeper and slightly more unstable marine layer may allow for better scattering in the late afternoons. The trough will certainly bring a string of high clouds across the area around Friday, helping reinforce cooler temperatures. There is potential for very isolated, weak thunderstorms along the trough Friday, but instability appears lacking in all models. Although there will be gusty southerly winds aloft, no model shows them mixing to the surface where weak north and west winds will persist. Most long range models show high pressure at least briefly rebuilding this weekend. /JHW

MARINE

Fresh north winds gusting up to 28kts have persisted across the outer waters today with steep seas up to 10 feet. Winds have been much calmer closer to shore, with gusts only around 12 kts with some seas up to 5 feet pushing in from the outer waters. Some stronger north winds will briefly push into the southern outer waters Tuesday evening and early Wednesday, mostly downwind of Cape Mendocino. Beyond short period seas, a very minor 2 foot, mid period southerly swell is augmenting the sea state. North winds gradually ease through the week with particularly calm conditions int he northern waters by Friday. /JHW

FIRE WEATHER

Hot and dry weather has peaked today with the hottest valleys reaching near 100 F and some RH values in the upper teens. Thermal belt strength will peak Wednesday morning with poor RH recovery as low as 30 percent along mid and upper slopes. Winds remain weak and terrain driven. Conditions will generally ease through the end of the week with increasing marine influence. Weak transport wind will continue to allow smoke accumulation around the MP18 fire in Hoop and up the Trinity River Valley, creating some extra, localized moderation of conditions.

The greatest forecast challenge remains thunderstorm potential around Friday. There is high ensemble confidence that a strong stream of midlevel tropical moisture will push across the area from the southwest early Friday morning and through the day. At the same time, a strong southerly jet forming offshore and aligning with topography could provide and lift and enhance instability to allow for thunderstorms. Even with this dynamic forcing, however, no model is consistently showing any amount of instability. Similar events have generated high clouds and virga, but little to no lightning. There remains a very slight (5%) chance of lightning in northern Trinity and Humboldt Counties Friday morning and afternoon, but coverage would be sporadic and very isolated. Any lightning that does occur will be dry, increasing fire risk. This forecast could quickly change if a source of instability materializes. /JHW

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 3 AM PDT Wednesday for PZZ455.

Small Craft Advisory until 9 PM PDT Wednesday for PZZ470.

Small Craft Advisory until 9 AM PDT Thursday for PZZ475.