Marine Weather and Tide Forecast for Santa Monica, CA

.SHORT TERM (TDY-MON)...10/150 PM.

The first of two upper lows is approaching the area this afternoon. So far most of the action has been from Monterey north, though light rain has fallen as far south as Carpinteria in southeast Santa Barbara County. The highest amount so far in the 4 county area belongs to Rocky Butte in northwest SLO County with just under a half inch.

Most of the high res models are indicating mostly minimal impacts through Saturday afternoon. Can't completely rule out a brief thunderstorm the rest of the day, mainly north of Pt Conception as satellite imagery shows a little convective boundary approaching the Central Coast and some afternoon heating and instability could help create some updrafts and brief moderate to heavy showers. Otherwise, just some scattered light showers with amounts mostly under a tenth of an inch, with some areas remaining rain free through tomorrow afternoon.

Then a bit of a break in the action later tonight into Saturday afternoon before the second upper low moves into northern California later Saturday night. Hi res models indicate increasing instability overnight into Sunday morning with around a 3-5 hour period of steady rain and possible thunderstorms moving through the entire forecast area. CAPE values of around 500j/kg will provide the necessary lift for convective activity, including brief heavy downpours, gusty winds, and possible lightning. Can't also rule out a small tornado or waterspout as models are showing sufficient helicity in the lower layers.

Rain amounts expected to generally be a half to one inch, except locally higher in the mountains and along the Central Coast. Due to the convective nature of this storm, rain amounts could vary quite a bit, even over very short distances. Rain rates expected to top out around a quarter to half inch per hour, except very brief and isolated rates as high as 0.75" in the strongest storms.

A Winter Weather Advisory was issued for the higher mountains, mainly above 5000 feet. Snow levels will be around 7000 feet through Sunday morning, then lowering to around 5000 feet Sunday afternoon into Monday morning. Snow accumulations of up to 6 inches are possible above 7000 feet, and 1-3 inches as low as 5000 feet. Not expecting any snow accumulations on the Grapevine over Interstate 5, though there could be a mix of rain and snow early Monday morning.

Drying conditions expected by Monday afternoon, if not earlier,

.LONG TERM (TUE-FRI)...10/146 PM.

Dry and warmer weather expected all of next week. Temperatures will warm 1-3 degrees each day. By mid week highs will be around 70 near the coast and near 80 inland. Possibly some light offshore flow developing Friday into next weekend.

AVIATION
10/2040Z.

At 19Z at KLAX, the marine layer was 1300 ft deep. The top of the inversion was at 2200 ft with a temperature of 13 C.

Moderate confidence in rain timing with a 30-50 percent chance of showers when mentioned in the TAF with 10-30 percent chance otherwise and elsewhere. IFR to MVFR cigs/vsbys possible in -shra.
There is 10-20 percent chance of thunderstorms KSBA and north through the period.

KLAX...Moderate confidence in TAF. There is a 20 percent chc of rain aft 04Z. No significant east wind component expected.

KBUR...Moderate confidence in TAF.

MARINE
10/1253 PM.

A weak Cold Front will move across the coastal waters through Saturday morning bringing showers and a slight chance for a thunderstorm north of point conception.

A second system will arrive later on Saturday into Sunday with a more traditional cold front. This stronger front will bring numerous showers and a slight chance for thunderstorms across all waters. Potential hazards include: heavy downpours, dangerous cloud to ocean lightning, small hail, and erratic gusty winds.
Boaters, especially those with small vessels should avoid these conditions.

LOX WATCHES/WARNINGS/ADVISORIES
CA...Winter Weather Advisory in effect from 9 PM Saturday to 11 AM PDT Monday for zones 353-376-377. (See LAXWSWLOX).
Winter Weather Advisory in effect from 3 AM Sunday to 11 AM PDT Monday for zones 378>380. (See LAXWSWLOX).
PZ...NONE.