textproduct: Eureka

KEY MESSAGES

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

* Elevated fire danger returns Saturday and into next week with periods of breezy winds and increasingly hot, dry conditions.

* Westerly to northeasterly winds through the weekend and into Monday will bring the greatest fire weather risk.

SYNOPSIS

Temperatures will be trending higher over the next week with moderate to major HeatRisk possible early next week. Hot interior temperatures in combination with periods of breezy winds this weekend through Monday with increase the fire weather risk.

DISCUSSION

Thursday small upper level low moved past the area in the afternoon, just bringing a few high clouds. High pressure buildings in slightly is trying to build back to the west, warming temperatures well inland by a few degrees. Closer to the coast the general west to northwest flow at the surface is expected to keep the coastal counties closer to normal. Stratus is expected to linger near or just off the this afternoon and quickly push inland Friday night. Saturday an upper level trough and associated frontal boundary is moving into the Pacific Northwest. Down here this front is expected to be dry, but could bring some drizzle where the marine layer persists. Saturday afternoon this expected to bring increasing north winds with gusts of 20 to 25 mph along the coast. Saturday night into Sunday northeast winds are expected to pick up over the ridges overnight, especially in Del Norte and Humboldt counties. Sunday afternoon these are expected to become northwest again and continue to increase.

Sunday night another trough is expected to move through Pacific Northwest and behind this high pressure starts to build over the eastern Pacific well off the coast. This brings some of the strongest winds northeast winds Monday morning in Del Norte and Humboldt counties. The 850 MB winds on the NAM increase to around 20 to 25 kt with low RH over the higher terrain. This will likely keep the coastal areas clear with this offshore flow. Hot inland temperatures are expected with highs over 100 in many of the valleys across the area. This brings fairly widespread areas of moderate heat risk. Warmer is expected to continue on Tuesday and this looks like the hottest day. Highs temperatures of 100 to 107 are expected in the valleys. Winds are expected to be lighter at the coast Tuesday and this could allow warmer temperatures to get closer to the coast. The alternate scenario of course is that the marine layer returns sooner than expected keeping temperatures cooler. Wednesday inland areas will start to cool by a few degrees as the ridge starts to get flattened. MKK

AVIATION

Light winds and mainly VFR conditions continue across the area this morning. Stratus has developed on the Del Norte and Humboldt coasts this morning bringing MVFR to IFR CIGS. This afternoon skies are expected to clear out at the coast again with some typical afternoon breezes. Confidence is low the on this clearing as usual. Stratus is expected to return at the coast again Friday night. MKK

MARINE

Northerly winds persist across the waters this morning, these are strongest south of Cape Mendocino with winds of 20 to 25 kt. These have diminished closer to shore this morning, but are expected to come closer to the coast in the afternoon.

Winds are expected to increase through the day on Saturday with gale force gusts expected in the afternoon south of Cape Mendocino. The 20 to 25 kt winds also expand farther north Saturday night and Sunday. By Sunday afternoon confidence is fairly high that the outer waters will at least see some gusts to gale force. It is possible they will come closer to the shore during the afternoon and evening hours, but will need to wait for the higher resolution models to get a better idea on that. Monday afternoon fairly strong gales are expected across the waters and these are expected to start to diminish on Tuesday. Winds are expected to be around 10 to 20 kt for much of the rest of the work week.

In addition to the steep wind driven waves there is a southerly swell Currently the Cape Mendocino buoy is showing it around 2 feet at 15 seconds. This may build to around 3 feet at and then slowly diminish through the middle of next week. MKK

FIRE WEATHER

Lighter winds and gradually increasing overnight relative humidity recoveries are expected through Saturday morning as a trough approaches the Pacific Northwest. Stronger marine layer pushes into the near-coast valleys and along coastal ridges are likely Friday and Saturday mornings. Farther inland dry air will remain in place with afternoon relative humidity values falling into the teens on Friday.

As the trough moves through the region on Saturday the pressure gradient will tighten resulting in stronger afternoon westerly winds with chances for gusts over 25 mph increasing to 50 to 70% for a good portion of the interior Saturday afternoon. Thankfully 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 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. This will need to be monitored as it gets closer. This will also impact the interior ridges of Humboldt, and Trinity counties.

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 not expected to be more than typical for the summer only lasting a few hours and not as strong as Saturday. MKK/RPA

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 3 PM PDT Saturday for PZZ455-475.

Gale Watch from Saturday afternoon through late Sunday night for PZZ455.

Small Craft Advisory from 3 PM Saturday to 3 PM PDT Sunday for PZZ470.

Gale Watch from Saturday afternoon through Monday morning for PZZ475.