Marine Weather and Tide Forecast for Rolling Hills Estates, CA

.SHORT TERM (SUN-WED)...09/758 PM.

***UPDATE***

A very shallow marine inversion is creating areas of fog along much of the coast this evening, with some dense fog noted along portions of the Central Coast. A Dense Fog Advisory will likely be needed at some point during the overnight hours, if the dense fog becomes more widespread. Models, including the HRRR, indicate that the shallow inversion could result in widespread fog, especially for the Central Coast and Santa Barbara South Coast.

High temperatures were noted across the valleys today with many readings in the mid 80s to lower 90s. As models indicate offshore gradients increasing some overnight, to -3.5 mb between LAX to Daggett, expect winds may be slightly stronger than today but still sub-Advisory level. While increasing offshore flow favors rising temperatures, the NAM12 indicated the 950 mb temps remaining similar in some areas, or decreasing slightly. Depending on how the marine inversion holds up, temperatures could warm at the coast.

***From Previous Discussion***

Upper level wind support wasn't strong enough with this Santa Ana event to push wind and hot temps to the coast today. Winds haven't been overly impressive with this event either with just a handful of sites over 25 mph. Models are still indicating a slight increase in offshore flow Monday but still with very minimal upper support so for the most part a very similar day as today except likely a few degrees warmer.

A significant cooling trend will begin Tuesday as high pressure weakens ahead of the next low pressure arrival. Gradients will quickly turn onshore and most areas will drop 5-10 degrees both Tuesday and again Wednesday. A deepening marine layer will push low clouds into the valleys by Wednesday morning with highs back down into the 70s.

.LONG TERM (THU-SUN)...09/1248 PM.

Starting to get some improved consensus in the models regarding the storm later in the week. Timing-wise models are zoning in on Thursday being the primary period for rain across the area, but with some early showers arriving Wednesday night along the Central Coast.

Models are also coming into better agreement on the amounts as well with a large percentage of the ensemble solutions showing a heavy, but relatively short period of rain as the main front moves through. Orographics will play a significant roll in the amounts with upslope areas getting twice to 3 times the amounts at sea level. Overall, sticking with the 1-2/2-4 inch range (coast and valleys/mountains), with much of that falling in 5-10 hour period, and hourly amounts between a quarter and half inch, and as much as 0.75 in the upslope areas.

Snow levels will likely remain at or above 8000' for most of the storm, then drop to around 6000 feet as the last of the precip is moving through later Thursday night into Friday morning. At this point it does not appear to be cold enough for snow on the Grapevine, but some light accumulations (2-4") are possible down to around 6000'.

Dry and cool weather expected next weekend with highs mostly in the upper 60s to low 70s.

AVIATION
10/0109Z.

At 2331Z at KLAX, the marine layer was 600 feet deep. The top of the inversion was near 1300 feet with a temperature of 29 degrees Celsius.

For the 00Z TAF package, high confidence in desert and valley site, but low confidence in coastal sites except for the Central Coast sites where moderate confidence exists in LIFR-VLIFR conds.
Further south along the coast, low confidence exists due to uncertainty in the timing and extent of CIGs . There is a 40% chance of LIFR-VLIFR conds for all coastal TAFs. The timing of low clouds arrival and dissipation could differ +/- 3 hrs from TAF times.

KLAX...Overall, low confidence in the 00Z TAF. There is a 30-40% chance of LIFR/VLIFR conditions overnight, most likely from 06Z to 15Z, but the timing could differ by +/- 3 hrs from TAF times. No significant easterly wind component is expected.
KBUR...High confidence in the 00Z TAF.

MARINE
09/732 PM.

For the Outer Waters and the Inner Waters north of Point SaL, moderate to high confidence in current forecast. Through Wednesday, high confidence in winds and seas remaining below Small Craft Advisory (SCA) levels. For Thursday and Friday, high confidence in a combination of SCA level winds and seas.
Additionally, there is a 30% chance of Gale force Thursday night across PZZ676.

For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. Through Wednesday, high confidence in winds and seas remaining below SCA levels. On Thursday and Friday, there is a 60-80% chance of SCA level winds with a 30-40% chance of Gale force winds.

LOX WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...NONE.