textproduct: Los Angeles

SYNOPSIS

04/225 PM.

Tropical Cyclone Marie, which will remain well offshore of SoCal, will bring impacts to the region over the weekend into early next week. Rain is favored late Saturday and Sunday focused over Los Angeles and Ventura Counties. Increasing southerly swell will create hazardous surf conditions at the coasts.

LONG TERM (TUE-FRI)

04/232 PM.

In the long term, there is uncertainty in the upper level pattern, especially mid week onward. Tuesday, there is moderate confidence in 500 mb heights rising over the region, along with continued warming temperatures to a few degrees above normal at the coasts and coastal plains, and a few degrees below normal farther inland. By Wednesay, Southwest California may become sandwiched between a ridge to the southeast and a trough (that will have entrained moisture from the remnants of Marie) to the west. This will keep the door open for additional tropical moisture. The associated southwest flow aloft may bring unsettled weather, although timing, location, and potential impacts are uncertain that far out.

AVIATION

04/1646Z.

At 1630Z at KLAX, the marine layer was 2600 feet deep. The top of the inversion was 4700 feet with a temperature of 17 degrees Celsius.

For 18Z TAF package, high confidence in CAVU conditions for valley and desert TAFs. For coastal sites, moderate confidence 18Z TAFs due to uncertainties with development of marine layer clouds.

KLAX...Moderate confidence in 18Z TAF. Timing of return of MVFR CIGs could be +/- 3 hours of current 11Z forecast. There is a 30% chance that CIG/VSBY restrictions do not develop overnight. No significant easterly wind component is expected

KBUR...High confidence in 18Z TAF as CAVU conditions are expected through the period.

MARINE

04/108 PM.

For the Outer Waters, moderate confidence in current forecast. Tonight through Saturday night, there is a 20-30% chance of Small Craft Advisory (SCA) level winds. For Sunday, there is a 60-80% chance of SCA level winds. For Monday through Wednesday, there is a 30-40% chance of SCA level winds.

For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. Today through Saturday, high confidence in winds and seas remaining below SCA levels. On Sunday and Monday, there is a 30-40% chance of SCA level winds in the afternoon and evening hours. For Tuesday and Wednesday, high confidence in winds and seas remaining below SCA levels.

For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. For a majority of the southern Inner Waters, high confidence in winds and seas remaining below SCA levels today through Wednesday. The only exception will be the western half of the Santa Barbara Channel where there will be 50-60% chance of SCA level winds late Sunday afternoon and evening.

Tropical moisture will stream over the area Sunday through Tuesday, bringing the threat of showers to the coastal waters. There is a 15% chance of thunderstorms Sunday afternoon for the waters south of the Channel Islands. A large southeast to south swell will also impact the area, causing increased currents and surges in the vulnerable harbors.

BEACHES

04/108 PM.

Significant coastal impacts are expected across Southern California beaches this Labor Day weekend. A large southeast to south swell from Hurricane Marie will moving into the coastal waters this weekend with swell heights of 5-8 feet and a period around 13 seconds.

High surf conditions are expected on south-facing beaches of Ventura and Los Angeles counties, peaking at 5-8 feet with local sets to 10 feet on Sunday and Monday. The Santa Barbara South Coast will be largely protected from this swell, but there are some small windows of southeasterly and southwesterly energy that could cause boosts in the waves. HIGH SURF ADVISORIES remain in place for Los Angeles and Ventura Counties, with BEACH HAZARDS STATEMENTS (a step below high surf advisories) in effect for Santa Barbara and San Luis Obispo Counties.

High tides will also be increasing through early next week. Due to a variety of reasons, the actual observed tides have been running 6 inches above predictions for sometime now. The south swell will likely enhance that enhancement. As a result, high tides should exceed 7 feet by Monday. Adding large tides like that with the south swell will result in a moderate risk for coastal flooding over the vulnerable south-facing shores. Areas of most concern include Avalon, Long Beach (Alamitos Peninsula), and Oxnard to Malibu (including Point Mugu). COASTAL FLOOD ADVISORIES remain in effect for Los Angeles and Ventura Counties where the best combination of tides and waves will occur, but Santa Barbara and San Luis Obispo Counties could also see some isolated issues.

LOX WATCHES/WARNINGS/ADVISORIES

CA...Coastal Flood Advisory in effect from 6 AM Saturday to 11 PM PDT Tuesday for zones 87-354-362-366. (See LAXCFWLOX). High Surf Advisory in effect from 6 AM Saturday to 11 PM PDT Tuesday for zones 87-354-362-366. (See LAXCFWLOX). Beach Hazards Statement in effect from Saturday morning through Tuesday evening for zones 340-346-349-350. (See LAXCFWLOX). PZ...NONE.