textproduct: Eureka

SYNOPSIS

Dry weather and above average inland temperatures will persist into next week. A weakening front will bring a quick chance for rainfall and a period of increased southerly winds. Otherwise, dry and warm weather will persist.

DISCUSSION

A weak front passed through the region and brought some accumulating light, coastal drizzle and persistent low clouds over Humboldt and Del Norte counties. Breezy northerly winds developed behind the front. High temperatures are greatly reduced over the interior behind the front as the embedded Desert Southwest ridge of high pressure weakens. Surface pressure is nosing in from the west, and will work to maintain above average inland temperatures. Areas in Southern Mendocino and Lake County will continue to see high temperatures in the high 70s to low 80s, brining some minor HeatRisk.

A stronger front will push into the Pacific Northwest early next week, with a trailing portion clipping Northern California. Precipitable water values will be anomalously high (200% above normal), but the front will likely struggle to maintain strength as it descends south against the southern ridge Tuesday through Wednesday. Southerly winds at 925 mb (near 2000 ft) will increase with the front Tuesday. This may bring a period of breezy conditions to some of the North Coast and interior ridges.

Probabilities for total rainfall in Del Norte County are only 40%, but a brief period of higher rainfall rates will still be possible is the front maintains better strength. NBM 90% (worst case) 24 hour rainfall does not reach an inch however. Dry warm weather will otherwise persist under high pressure. The next hint of a pattern change toward wetter weather does not arrive until near the end of the month.

AVIATION

Gusty winds have mixed down, starting a bit earlier than expected at KCEC and KUKI with northerly winds sustained around 15kts gusting 26-30kts. KCEC is expected to have gusts still hanging around 20kts into late evening (~08z) with KUKI gusts easing a bit sooner (~03z). KACV is a bit more protected geographically with sustained winds 10 to 15kts easing tonight by 03z. Cloud cover at the terminals is projected by NBM and HREF to linger around Humboldt bay and south to the halfway point of Cape Mendocino at latitude 40.4 and probably inland to about the longitude -123.8. The post frontal conditions are likely going to have a clearing effect overnight with the exception of the previous area mentioned. Cold cirrus clouds aloft and a slight moisture flux may not be enough to overcome the winds as far as visibility and ceilings go. VFR for our area terminals through the evening and well into Sunday. /EYS

MARINE

Very hazardous ocean conditions are forecast this weekend. North wind gusts from 34 to 42 kt are highly probable (>80% chance), primarily over the outer waters and inner waters south of Cape Mendocino. A gale warning is in effect. A long fetch of strong northerly winds will generate very steep waves from 10 to 15 feet with periods from 8 to 10 seconds by Saturday afternoon and evening. Waves this large and steep will be capable of capsizing small vessels and mariners are encouraged to remain in port. A hazardous seas warning has been issued for northern inner waters with very steep waves forecast to build to 10 ft or more Sat evening and Sat night. These very steep waves will continue Sunday morning. A secondary ramp up in very steep waves will occur Sunday afternoon and evening for the inners. For the outers, waves will remain very steep and treacherous through at least early Monday morning.

Outlook going into next week: Conditions will begin to ease up and subside on Monday with lower seas into Tue. Conditions deteriorate again around mid week as a large mid period W-NW swell arrives and potential for northerly gales increases after frontal passage.

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 5 PM PDT this afternoon for PZZ450.

Hazardous Seas Warning until noon PDT Sunday for PZZ450.

Gale Warning until 3 PM PDT Sunday for PZZ455.

Gale Warning until 9 PM PDT Sunday for PZZ470-475.