textproduct: Eureka

SYNOPSIS

An approaching cold front will bring much cooler temperatures Friday and Saturday. This front is also expected to bring some light rain to the area on Friday, mainly in the afternoon in Del Norte and northern Humboldt county. Breezy winds are expected behind the front Friday evening through Saturday. A gradual warming trending is expected Sunday and into early next week.

DISCUSSION

Water vapor satellite shows a frontal boundary approaching the area with the upper level low well to the north and still in the Gulf of Alaska. The front has started to impact the area this afternoon weakening the marine layer and cooling temperatures inland. The near coastal areas are already seeing to 10 to 15 degree cooler temperatures this afternoon and areas farther inland are running a few degrees cooler than yesterday. Tonight the marine clouds are expected to come back, but the ceilings may be higher with less fog around. Tonight mid and higher level clouds are expected to spread across the area. Some drizzle is possible later tonight. Friday periods of light rain and drizzle are expected along the north coast as the weak front moves through the area. The probability of a wetting rain (0.10 inches) has increased some with nearly a 100 percent chance in Del Norte county with a 50 to 90 percent chance in Humboldt county. Areas farther south and east are showing less than a 50 percent chance of a wetting rain. Along with the front and behind there are expected to be breezy winds. These will initially be strongest Friday night over the mountains of Lake, eastern Mendocino and Trinity counties spreading across the rest of the area on Saturday. A few gusts to 35 mph are possible in the eastern mountains with most areas just seeing gusts to 25 to 30 mph. Skies are expected to slowly clear on Saturday with rain or drizzle generally coming to an end in the morning. The low will be moving overhead and this will keep temperatures cool with most valleys expected to see highs only in the low to mid 70s with higher elevations staying cooler. The cold air aloft may allow a thunderstorm to develop in northeastern Trinity county, however if this does occur the northwest flow will likely move it out of the area quickly. Saturday night frost is possible in some of the coldest spots in eastern Humboldt and Trinity counties.

Sunday high pressure starts to build back into the area and temperatures are expected to start gradually warming. The upper 70s to near 80 is expected on Monday with highs in the 80s by Tuesday and Wednesday. Some cooling is possible by Thursday. The layer will likely be fairly limited on Sunday with a weak inversion, but is expected to start expanding and becoming more persistent again early next week. MKK

AVIATION

The marine layer has started to deepen with the approaching frontal boundary and this has brought CIGS up to MVFR this afternoon with a few breaks in the clouds. Tonight CIGS may drop along the coast slightly in the evening, but with the approaching front and trough these may lift some overnight. The HREF shows MVFR conditions Friday morning with only a 10 to 20 percent chance of ceilings below 1,000 feet. Friday MVFR conditions are expected along the coast with VFR conditions possible at points during the late morning. Some inland areas are expected to see valley fog, but the HREF is keeping the stratus farther away from KUKI and they may remain clear overnight. Around midday the incoming front will bring some light rain and drizzle and this is expected to eventually drop cigs into MVFR in the afternoon. These conditions are also expected to extend well inland in the coastal counties.

MARINE

Northerly winds continue to weaken tonight and Friday. This afternoon these winds are around 10 to 20 kt with the strongest winds in the southern waters. These continue to diminish tonight. The waves are a mix wind driven waves and a southerly swell around 3 feet at 18 seconds. Friday as the winds continue to diminish a fresh northwest swell lingers around 3 to 4 feet at 6 seconds. Friday night and Saturday the winds start to increase again and are expected to be 15 to 20 kt by Saturday afternoon. High pressure starts to build in on Sunday and the winds slowly continue to increase. Gale force gusts are possible by Sunday afternoon in the southern waters. Farther north winds remain a bit lighter. Monday and Tuesday winds remain near gale or gale, especially south of Cape Mendocino. The winds are expected to start to relax by mid-week. The waves are expected to be mainly wind driven, but a small southerly swell is expected to persist through the middle of the week. MKK

FIRE WEATHER

A major pattern shift arrives Friday as an unseasonably strong trough and cold front push ashore. Wetting rain is likely across coastal Del Norte County (90 to 100 percent chance of exceeding 0.10 inches), while a 50 to 90 percent chance of wetting rain exists for northern Humboldt County. Southern and eastern zones will remain dry outside of isolated sprinkles. Interior temperatures will drop 10 to 20 degrees from Wednesday by Saturday. As the core of the cold trough positions overhead Saturday afternoon, localized destabilization will support a 10 percent chance of thunderstorms across northern Trinity County.

Stronger westerly winds develop behind the front Friday evening across Lake and southern Mendocino counties, bringing a 70 percent chance of gusts exceeding 30 mph in lower elevations and a high probability of gusts over 40 mph across exposed ridges. Breezy conditions persist Saturday before winds shift to the northeast across Lake County by Sunday afternoon. The RH is expected is expected to remain fairly high during these winds somewhat mitigating the fire risk. Recoveries Saturday morning are expected to be 80 to 100 percent with afternoon RH Saturday only dropping down into the 40s in the drier areas. MKK

EKA WATCHES/WARNINGS/ADVISORIES

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