Marine Weather and Tide Forecast for Rancho Palos Verdes, CA

.SHORT TERM (TDY-SUN)...14/842 AM.

***UPDATE***

Rather deep marine inversion this morning, from around 3400 feet deep at LAX to near 3900 feet deep at VBG. Low clouds covered the coast, vlys including deeper inland vlys, and coastal slopes this morning. At mid-morning, the low clouds were starting to dissipate back toward the coast and this trend should continue thru midday, with most areas having mostly sunny skies this afternoon. Good onshore flow can be expected this afternoon with breezy to gusty SW to W winds. Temps will be about 4-10 deg cooler-than-normal across the region today, with highs from the 70s along the coast to the 80s inland, except around 90 in the Antelope Vly.

Current forecast is on track and no updates are expected this morning.

***From Previous Discussion***

The weak troughing along the West Coast has indeed brought much cooler than mid-August normal temperatures to Southwest California. A large area of high pressure will begin to build further west, slowly but steadily increasing 500 mb heights over Southwest California. In conjunction with weakening onshore flow, temperatures will begin to rise each day. Although we will see the gradual warming trend kicking off today, temperatures are still forecast to remain below seasonal normals through the weekend.

The very deep marine layer has yet again spread all the way into interior SLO and Santa Barbara Counties, and it will continue to move deeper in the the valleys south of Point Conception. In fact, clouds are already making their way into Santa Clarita Valley.
The marine layer depth and thus extent of inland coverage will decrease each day due to the increasing 500 mb heights and weakening onshore flow, and likely only the coasts and some lower valleys will see marine layer clouds come Sunday. The absence of morning low cloud coverage will also help accelerate the warming over the valleys, while coastal areas will see the smallest warming.

Due to the position of the trough, morning drizzle is possible through the weekend, as is afternoon mountain convection (10% chance). The atmosphere has lost a lot of its juice in terms of available mositure, so we will most likely just see a few cumulus buildups.

.LONG TERM (MON-THU)...14/1248 AM.

A fairly benign pattern will continue through the forecast period, although high temperatures will continue to warm to near seasonal normals by mid-week and the large ridge of high pressure builds further west until it eventually centers across the Southwestern US. Any night through morning low clouds and fog should become confined to the coast by Monday. While there is good agreement amongst models through Wednesday, beginning Thursday there becomes more disagreement in how the pattern will evolve into the weekend.
Some ensemble members suggest the ridging to continue and potentially intensify, while others favor a troughing pattern moving in and pushing the ridge to the east.

A northerly surface pressure gradient is forecast to develop early next week, likely bringing gusty northerly winds across southern Santa Barbara County and through the Interstate 5 Corridor. Advisory level Sundowner winds could develop during this time, but there is some uncertainty in the timing and the actual strength of the winds.

AVIATION
14/1721Z.

At 1649Z at KLAX, the marine layer was 2600 feet deep. The top of the inversion was near 4500 feet with a temperature of 19 C.

High confidence in VFR TAFs for KPMD & KWJF.

Moderate confidence in remaining TAFs. 40-50% chance of no clearing at KSBP/KSMX, respectively, and only a few hours of clearing at KPRB. Arrival of MVFR cigs tonight may be off +/- 4 hours from forecast, lowest confidence south of Point Conception.
KSBP and KSMX may drop to IFR conds overnight Friday into Saturday.

KLAX...Moderate confidence in TAF. Cigs should clear sometime 17Z-20Z. Arrival tonight may be +/- 3 hours off from forecast.
No significant east wind component expected.

KBUR...Moderate confidence in TAF. Cigs should clear sometime 16Z-19Z. Arrival tonight may be off +/- 3 hours.

MARINE
14/812 AM.

High confidence that conditions will remain below Small Craft Advisory (SCA) criteria across all coastal waters through Saturday morning. There is a 30-50% chance of SCA winds across the outer waters and the western portion of the inner waters starting Saturday afternoon, with the highest chances for the waters south of Point Conception and the Santa Barbara Channel during the afternoon/evening hours. Chances increase Sunday afternoon, and at least SCA conds will continue through mid-week. Gusts of 30-35 kt will be possible starting Monday, with highest likelihood around Point Conception and the outer waters north of Point Sal. Seas may approach 10 ft across portions of the Outer Waters Tuesday and Wednesday.

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