textproduct: Eureka

KEY MESSAGES

* A deep marine layer and cooler temperatures aloft will combine to bring near to slightly below normal temperatures this weekend.

SYNOPSIS

A deep marine layer and cooler temperatures aloft will combine to bring near to slightly below normal temperatures through the weekend. The coast may finally see more clearing over the weekend. Some warming is expected Sunday and Monday before another trough brings cooler temperatures next week.

DISCUSSION

An upper level-open wave trough crowds into the PACNW coastline over the few days. This pacific low is a part of a larger pattern, Omega block, which has high pressure ridging set up in the interior with peak amplitude extending into Canada. The positive tilt of the pacific area trough has kept the potential for convection and consequently lightning probabilities low. That and the sourced tropical moisture being pulled into the area via elongated troughing motion has also paired with the deepening marine layer to quell high temperatures inland and rebound overnight recovery RH values, further suppressing fire weather behavior.

Saturday the upper level low starts to move out of the area with high pressure filling in behind it. This will bring cooler temperatures aloft which will keep the inland areas mainly in the 80s with 70s closer to the coast. This may finally bring some clearing and breezy afternoon winds. The cooler temperatures aloft will weaken the marine inversion. Saturday night into Sunday morning there is some offshore flow and this may help clear skies out more quickly during the day. It doesn't look strong enough to keep skies clear overnight.

Monday through the middle of the week a trough starts to approach the area bringing cooler temperatures and deeper marine layer again. This will come more from the west, thunderstorms look unlikely.

AVIATION

The deepening marine layer has lifted the cloud base and kept ceilings 1300-1500ft at the coastal terminals, locking flight categories into MVFR with periods of VFR as skies scatter out and fill back in with offshore stratus persisting. Satellite products in the visible spectrum confirm what models are also predicting for this evening, IFR conditions with ceilings coming down below 1000ft. The marine layer will hold the cloud base around 700ft or so for KACV and KCEC with a few periods of sub 500ft ceilings at KCEC being signaled for a few hours. That said, offshore winds at KACV could help keep visibility improved overnight as well. Mostly prevailing VFR conditions at KUKI overnight with gusty northerlies late Saturday afternoon. /EYS

MARINE

Calm seas and light to gentle breezes are expected through early Saturday. Moderate northerly winds return to the outer waters Saturday afternoon and increase through Sunday with localized gusts near Gale, south of Cape Mendocino and fanning out into the southern outer waters. A small craft advisory has been hoisted for the southern waters late Saturday night/early Sunday morning as well as the northern outer waters which start Sunday evening.

FIRE WEATHER

Marine influence has will continue to increase through the end of the weekend. High clouds will aid in the warmest interior temperatures pulling back closer to 90 with RH closer to 25 percent. Mid and upper slope recoveries will also improve though remain poor on higher peaks. Warmer, near average conditions will return Sunday and into early next week.

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... None.