textproduct: Eureka

KEY MESSAGES

* Hot temperatures return early next week with widespread Moderate to locally Major HeatRisk through mid week

* Elevated fire danger returns this weekend with breezy northwest afternoon winds, although this will diminished some by slightly cooler temperatures and higher afternoon RH.

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

SYNOPSIS

Slightly cooler temperatures inland are expected for the weekend with breezy afternoon winds. Temperatures will be trending higher Monday and Tuesday with moderate to major HeatRisk expected early next week. Temperatures will diminish slightly mid to late in the week, but remain hot.

DISCUSSION

An upper level trough moving into the Pacific Northwest on Saturday will bring slightly cooler temperatures across the inland areas with many areas seeing temperatures 5 or so degrees cooler. Eastern Lake county may be the exception with highs still near 100. This will also bring some breezy northwest afternoon winds. These winds are expected to be strongest in the coastal counties with some stronger winds extending into Trinity and western Lake counties. Gusts of 25 to 30 mph are expected in the higher terrain and exposed areas along the coast. The northwest winds will slightly increase the afternoon RH and therefore limiting the fire threat to some extent. Saturday night into Sunday morning the offshore flow starts to develop, mainly in Del Norte county. Sunday morning the RH recoveries are still expected to be over 60 percent even at the higher elevations of Del Norte, Humboldt, and Trinity counties. This offshore flow should be enough to keep stratus limited in the coastal areas. Sunday afternoon north to northwest winds are expected again. The winds speeds are expected to be similar to Saturday, although afternoon RH is expected to be slightly lower.

Sunday night into Morning is expected to see the strongest offshore flow. This will mainly be in Del Norte county and to a lesser extent in northern Humboldt and northern Trinity counties. Gusts to 30 to 40 mph are possible on the higher peaks with the potential for RH recoveries of only 35 to 40 percent. One source of uncertainty that remains is how low will this dry air and gusty winds get. This will increase fire danger overnight, for details see the fire weather section.

Monday afternoon the ridge starts to strengthen and hotter temperatures are expected across the interior. Many of the interior valleys are expected to exceed 100. Winds are expected to be breezy along the coast, but more in line with typical summer afternoons and lighter than over the weekend. Monday night into Tuesday offshore winds are expected to be lighter and some stratus may form locally 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. MKK

AVIATION

Stratus remains fairly thin due to a weak inversion. This is expected to allow skies to clear out by mid to late morning on Saturday. The HREF and the REFS both show stratus returning late in the afternoon along the Humboldt coast including ACV. Then late in the evening clearing out again. There is some offshore that could help with this clearing, but confidence remains low on it. Breezy north to northwest winds are expected across much of the area with gusts of 20 to 25 kt.

MARINE

Northerly winds continue to be strong south of Cape Mendocino with lighter winds farther north. Saturday morning these stronger winds are expected to push farther north. Gales are expected in the southern waters in the morning. For the northern waters the small craft advisory starts in the morning as well, but this may need to be delayed, there is some uncertainty on how quickly the winds will move north. Later in the afternoon and evening the winds are expected to get closer the coast and increase in the northern outer waters. In addition to the wind driven waves there is a small southerly wave lingering around 2 feet at 14 seconds. This is expected to continue to diminish over the next several days.

Winds are expected to peak Sunday afternoon across much of the area. Sunday evening and overnight the stronger winds are expected to push farther off the coast so have the advisory and gale warning dropping off in the inner waters. The winds are expected to turn more the northeast as well so even in the winds near the coast remain slightly elevated, the fetch will be limited. The winds are expected to drop below gale on Tuesday, but winds are generally expected to remain around 20 to 25 in the outer waters. Closer to the coast we may see a flow reversal with localized southerly winds. This may be Tuesday or Tuesday night. MKK

FIRE WEATHER

Lighter winds and gradually increasing overnight relative humidity recoveries are expected through Saturday morning as a trough approaches the Pacific Northwest. A stronger marine layer pushes into the near-coast valleys and along coastal ridges Saturday mornings. As the trough moves through the region on Saturday the pressure gradient will tighten resulting in stronger afternoon westerly winds with gusts over 25 mph for a good portion of the interior Saturday afternoon. However, the west- northwesterly winds will also bring slightly increased relative humidity with minimums in the 20s instead of teens. This will keep the fire threat from becoming critical. Sunday 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 on the ridges and possible the northeast aligned drainages. The 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 with higher RH 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 from 3 PM Saturday to 9 PM PDT Monday for PZZ450.

Small Craft Advisory until 9 AM PDT Saturday for PZZ455-475.

Gale Warning from 9 AM Saturday to 9 PM PDT Sunday for PZZ455.

Small Craft Advisory from 9 AM to 9 PM PDT Saturday for PZZ470.

Gale Warning from 9 PM Saturday to 3 AM PDT Tuesday for PZZ470.

Gale Warning from 9 AM Saturday to 9 PM PDT Monday for PZZ475.