Marine Weather and Tide Forecast for Santa Monica, CA

.SHORT TERM (THU-SUN)...23/931 PM.

***UPDATE***

Temperatures were quite warm for the valleys and coasts today as Santa Ana winds continued this morning into tonight. Unlike yesterday, winds remained offshore over the Ventura County Coast and highs climbed into the low 80s, with 70s to low 80s common through most valleys and coasts. Tomorrow, expecting a significant change as Santa Ana winds finally weaken early in the morning and onshore flow returns. Temperatures should fall to the upper 60s to 70s for Friday, with increasing clouds as the low pressure system approaches.

Santa Ana winds are expected to last through tonight into early Friday morning. Currently, winds are mostly below wind advisory thresholds, which a few areas in the Santa Monica mountains, Santa Susana Mountains, and San Gabriel mountains gusting near 50 mph. Expecting those lingering gusts to trend weaker tonight.

The current forecast for Saturday looks on track with a low moving into the region, bringing a chance for rain, thunderstorms, and snow. May need to consider increasing rainfall totals for the Santa Lucia mountains, but confidence is a bit lower as the track of the low will highly influence precipitation totals.

***From Previous Discussion***

Offshore gradients have peaked and are trending weaker. Expecting this trend to continue through tonight and turning onshore later on Friday. While gradients will be weakening, lingering Santa Ana winds are still expected through Friday morning, especially over the higher terrain in LA/Ventura Counties. Most coastal areas will transition to an onshore sea breeze Friday afternoon, resulting in a significant cooling trend from around 80 today to high 60s Friday. Valleys and other inland areas should have another warm day.

Attention then turns quickly to the upper low that will be moving into the area this weekend. The most notable change in the models today was a slightly slower arrival into central and southern California. Models now are keeping the low north over the Bay Area through midday Sunday, then near Pt Conception Sunday night. If this timing holds it would likely delay the onset of showers later into Saturday or possibly into early Sunday for southern and eastern portions of the area. Other than that, there's still a lot uncertainty with how this storm will play out in our area.
Ensembles continue to cluster tightly around the quarter to half inch range for a storm total across areas south of Pt Conception and slightly less to the north. But there are still are around 25% of the solutions that are a notch higher. A lot will depend on the actual track of the low and whether it goes more over water or more inland. For now, the forecast follows very close to the ensemble means, referenced above, which is quite a bit lower than the NBM forecast which seems to be more of a worst case scenario solution. Given the pattern and the possibility of thunderstorms, the ensemble mean forecast will likely represent most of the area best, while the higher NBM forecast will represent much smaller pockets of the area where the higher rain rates occur. For our burn scars, especially the most recent ones this month, chances are still very low, around 5-10%, that rates will exceed the half inch per hour rate. Peak rain rates are generally expected to be a quarter inch per hour, and for much of the time a tenth of an inch per hour or less.

Snow levels with the morning runs weren't quite as low as before, now keeping the snow level slightly above 4000 feet through Sunday evening. In this scenario it's unlikely the Grapevine will see anything more than a dusting of snow at pass level. If the low drops farther south Sunday night into Monday there could be up to an inch on the Grapevine during that time. Elsewhere in the mountains from 4500 and up, accumulations will range from an inch to as much as 10 inches above 6500 feet.

Obviously much cooler this weekend. Saturday highs 55-60 for most coast/valleys areas, and about 5 degrees cooler Sunday with off and on showers.

.LONG TERM (MON-THU)...23/235 PM.

As the storm clears out on Monday night and into Tuesday, there is a moderate chance of cold air mass being left in its wake. A widespread frost and freeze event could develop with frost advisories being needed for the colder Los Angeles County valleys, the Ventura County coast and valleys, and the Santa Barbara and San Luis Obispo coastal areas. Tuesday morning could end up being the coldest morning for the coastal and valley areas.

AVIATION
24/0552Z.

At 0424Z at KLAX, there was no marine layer nor an inversion.

High confidence in VFR conditions at all sites.

Lgt-isold mdt turbc over and near to hier trrn thru 18Z.

KLAX...High confidence in VFR conds. Good confidence that any east wind component will be 6kt or less.

KBUR...High confidence in VFR conds. Lgt-isold mdt turbc is possible thru 18Z.

MARINE
23/818 PM.

In the Outer Waters, some local SCA level gusts may occur through around midnight, especially between the Santa Rosa Island and San Nicolas Island, otherwise winds will continue to trend down through tomorrow morning. Otherwise, tonight thru Sat morning, SCA conds are not expected. There is a 50-60% chance of SCA level seas Sat morning thru Sun, and a 30% chance of SCA level NW winds Sat morning thru Sat night, with best chances north and west of Point Conception. Then, sub- advisory conds are expected through Tue.

In the Inner Waters off the Central Coast, there is a 20% chance of SCA level seas Sat/Sat night. Otherwise SCA conds are not expected thru Tue night.

In the Inner Waters south of Point Conception:

From Ventura to Malibu and out to Anacapa and E Santa Cruz Island, winds have begun to taper off, but SCA level gusts are expected nearshore with a chance of continuing through 300 AM.
Issued a SCA with the nearshore gusts and rough seas expected nearshore, although there is a 30-40% chance the gusts will end by around midnight. Thru the San Pedro Channel south to off the coast of Orange County, local SCA level gusts may occur through tonight, but moderate to high confidence in the strongest winds being behind us. Elsewhere, winds will remain sub- advisory through tonight. After Fri morning, SCA level winds are not expected thru Tue.

LOX WATCHES/WARNINGS/ADVISORIES
CA...Frost Advisory remains in effect until 9 AM PST Friday for zones 340-341-349-350. (See LAXNPWLOX).
Freeze Warning remains in effect until 9 AM PST Friday for zones 346-347-357-383. (See LAXNPWLOX).
Winter Weather Advisory in effect from 4 PM Saturday to 4 PM PST Monday for zones 353-376>380. (See LAXWSWLOX).
Red Flag Warning in effect until 10 AM PST Friday for zones 288-354-355-358-362-369>380. (See LAXRFWLOX).
PZ...NONE.