textproduct: Eureka

KEY MESSAGES

* Coastal warmup Sunday and Monday with offshore flow.

* Hot temperatures return Monday and Tuesday with widespread Moderate to locally Major HeatRisk through mid week.

* Elevated fire danger continues Sunday with breezy northwest afternoon winds.

* Sunday night into Monday morning northeasterly winds and poor RH recovery will increase fire danger mainly in Del Norte, Humboldt and Trinity counties.

SYNOPSIS

An upper level trough moving by to the north of the area is expected to bring breezy afternoon winds today and offshore flow tonight. This is expected to keep coastal areas mostly clear and above normal. High pressure builds in Monday bringing hot temperatures with many of the inland valleys warming to near 105. Slight cooling is expected late in the week.

DISCUSSION

An upper level trough moving into British Columbia will bring breezy northwest winds again this afternoon. Gusts of 25 to 30 mph are possible along the coast and near the coast over the higher terrain. Temperatures are expected to warm a few degrees inland with most areas in the mid to upper 90s. RH is also expected to drop slightly.

Monday and into mid week will be defined by an upper level high pressure system centered over the Southwestern US building west into Northwest California. This will aid in warming and drying out the region, especially interior regions of Northwest California. There is potential for moderate to major HeatRisk by Monday and Tuesday, mostly for interior Mendocino, Trinity and Lake counties (specifically: the Klamath River Valley up river from Weitchpec, the Trinity River Valley, the hottest valleys of southern Trinity and southern Humboldt, the Eel River Valley in NE Mendocino, the Round Valley, Potter Valley, Russian River Valley in southern Mendocino and the hottest valleys of Lake County). On Monday (in the areas previously mentioned), ensemble models indicate a 65 to 80 percent chance for high temperatures over 100 degrees with Tuesday looking at a 75 to 90 percent chance. This leads to moderate to locally major heat risk in interior Mendocino and Lake counties on Monday and this spreads north across the area on Tuesday. So have issued a heat advisory for portions of Mendocino and Lake counties for Monday and Tuesday. This will likely need to be expanded farther north on Tuesday. Relative Humidities will also be very low (10 to 20%) Monday through Thursday. With the warming and drying winds, there is an elevated Fire Danger for next week (more details in the Fire Weather Section).

Additionally, a surface ridge in the NE Pacific is migrating east bringing strong northerly winds to the area along with general offshore and downslope flow. This offshore flow will begin overnight tonight and continue to some degree through Tuesday morning. Offshore flow will be most pronounced over Del Norte County Monday morning, but will be prominent over high elevation regions throughout Northwest California and also affecting coastal locations. This pattern will aid in warming and drying coastal and near coastal areas. Ensemble Models indicate a 60 to 90 percent chance for temperatures over 70 degrees for coastal southwestern Humboldt and the Mendocino Coast through the next couple of days. Also, on Monday, there is a 55 to 75 percent chance for over 70 degree highs at the Eel River Delta, around Humboldt Bay and along the Humboldt Coast up through the Del Norte Coast with a slightly higher chance on Tuesday. By Monday, there is about a 65 to 75 percent chance for high temperatures above 75 degrees along the Del Norte Coast.

One thing to note with these higher than average temperatures along the coast is that the gradient for the warmest temperatures will be very steep and very dependent on the presence and persistence of offshore and downslope flow. Where there is little downsloping occurring, temperatures will not be as warm.

Monday night and into Tuesday offshore winds are expected to be lighter with some stratus potentially forming in localized areas along the Humboldt coast. Tuesday, winds are expected to be lighter at the coast. This may allow a southerly surge of clouds and south winds to start moving north. The models show this starting Tuesday night, but sometimes this happens earlier than expected. Tuesday afternoon may be the warmest along the Humboldt coast with the lighter winds if the marine layer doesn't return. Wednesday and Thursday temperatures are expected to start cooling by a few degrees in some locations, but overall it looks to remain hot. /JLW/MKK

AVIATION

VFR conditions are in place across much of the area this morning. A few areas of clouds are in the mountains of Humboldt county, but the offshore flow is expected to keep these from reaching KACV and KCEC this morning. If they do make it in, the CIGS should be MVFR and are expected mix out fairly quickly once again in the morning. This afternoon breezy winds are expected once again, although they might be slightly weaker than on Saturday. Tonight winds are expected to be offshore again and that should keep most of the stratus away. MKK

MARINE

Winds and waves continuing to increase with gales spreading north of Cape Mendocino. This afternoon the gales are expected to move closer to the coast and the gale warning remains on track. Monday the winds in the southern waters will start to gradually move farther off the coast. The gale in the southern outer waters may end sooner than the warning, but for now will leave it the same. Winds are expected to gradually diminish through the week before increasing again over the weekend. MKK

FIRE WEATHER

This afternoon breezy winds are expected again, although they will be slightly more limited to the areas closer to the coast. RH is expected to be slightly lower as well for the Trinity and Lake counties with the warmer valleys dropping into the high teens in the afternoon.

Sunday night into Monday morning is starting to look like a more critical time period, especially on the ridges of Del Norte county. Gusts of 30 to 40 mph are are possible at the ridges and possibly the northeast aligned drainages. It is also expected to be fairly dry. The challenge at this point is determining where the inversion will be with dry and breezy conditions above and much calmer and higher RHs below it. The current forecast is now showing a fairly big area of eastern Del Norte county with recoveries of only 30 to 40 percent. This will also impact the interior ridges of Humboldt, and Trinity counties to a lesser extent. This will need to be monitored as it gets closer.

Afternoon RH will trend much lower across the interior to the low teens and likely some single digits by Monday and then remaining dry into mid next week. Afternoon west-northwesterly gusty winds can be expected each afternoon. These winds are expected to be more typical for the summer afternoons only lasting a few hours and not as strong as over the weekend. MKK

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 11 AM PDT Sunday for PZZ450.

Gale Warning from 11 AM to 9 PM PDT Sunday for PZZ450.

Gale Warning until 9 PM PDT Sunday for PZZ455.

Small Craft Advisory until 9 PM PDT this evening for PZZ470.

Gale Warning until 3 AM PDT Tuesday for PZZ470.

Gale Warning until 3 AM PDT Tuesday for PZZ475.