05/330 PM.
Tropical Cyclone Marie, which will remain well offshore of SoCal, will bring impacts to the region through at least early next week. Rain is favored early Sunday morning into the evening, focused over Los Angeles County. Rain will mostly be light to moderate, but there is a 15 percent chance of thunderstorms for Los Angeles County on Sunday. Increasing southerly swell will create hazardous surf conditions at the coasts.
(Sat-Tue), 05/803 PM.
***UPDATE***
The large scale pattern features a large upper level low centered over coastal Oregon, and Hurricane Marie, 700 miles south of Point Conception. Marie is forecast to move west to northwest over the next couple of days, weakening below Hurricane strength Sunday night. While Marie is not forecast to move close to southern California, the impacts of this storm are already affecting the area. Southerly swells are creating large, hazardous surf and rip currents at area beaches, and tropical moisture will move over the area later tonight. Along with increasing mid to upper level clouds, there will be rain chances beginning after around 5 AM Sunday through Sunday evening. Mostly light rain is expected, and most of the rain in general will affect LA County.
In addition, there will be a slight chance of thunderstorms over LA County and the adjacent coastal waters Sunday afternoon, with the best likelihood over the mountains and foothills. Any clearing that occurs during the day would help to kick off convective showers due to surface heating providing lift for the fairly significant moisture moving over the area. There is a chance of heavier rain occuring near any thunderstorms that form. Mainly light rain is expected across portions of Ventura County and southeastern Santa Barbara County.
Rain totals are expected to be around 0.25 inches or less for most areas in LA county, except higher amounts in the foothills of the San Gabriel Valley (0.5 inches likely) and the eastern San Gabriel Mountains (locally to around 1.0 inch). Rain totals will generally be 0.10 inch or less for Ventura and Santa Barbara Counties. Rain rates could be up to around 0.20 inch per hour for most areas, except for locally heavier showers mentioned above, producing brief rates of 0.25 to 0.50 inch per hour. There is only around 5 percent chance of rain rates high enough to cause minor/urban flooding in LA County but roads could become slick and dangerous due to the buildup of oil after many dry months.
***From Previous Discussion***
Temperatures will feel warmer over the weekend with the additional humidity, but still remain within a few degrees of normal. Overnight lows could be quite warm and only into the 70s for our southern coasts and coastal valleys where the topical mositure will be the greatest. Monday and Tuesday will see slight warming each day, with continued humid conditions that will produce moderate Heat Risk, especially near the coast. On Monday, we can't rule out a stray shower or isolated thunderstorm, but for the most part expect dry weather. Tuesday, there is around a 50 percent chance of showers (and thunderstorms), this time focused over Santa Barbara County and San Luis Obispo County.
(Wed-Sat), 05/236 PM.
There is lower than normal forecast confidence for the overall pattern and rain chances in the long term. Remnants of Marie are likely to remain in the general region for much of next week and forecast models have struggled to resolve the impacts. Scattered showers and thunderstorms will be possible Wednesday, focused for Ventura County and the Central Coast. There is a moderate chance that a ridge will build over SoCal by late this week, thus temperatures are favored to warm with areas of at least moderate HeatRisk for Wednesday and Thursday. Please stay tuned if heat and/or rain may impact your plans next week, as forecast details may change.
06/0155z.
At 0013Z at KLAX, the marine layer was 700 feet deep. The top of a weak inversion was 1800 feet with a temperature of 25 deg C.
High confidence in CAVU conditions for all sites through this evening. Overnight, moderate confidence in current forecasts as tropical moisture moves in, bringing the threat of light showers and could wreak havoc with stratus formation.
KLAX, Moderate confidence in TAF. CAVU conditions are expected through this evening. Overnight and through Sunday, there is a 30-40% chance of BKN015-025 CIGs. Light showers are expected to develop Sunday morning. No significant easterly wind component is expected.
KBUR, Moderate confidence in TAF. CAVU conditions are expected through this evening. Overnight and Sunday morning, there is a 20-30% chance of BKN015-025 CIGs. Light showers are expected to develop Sunday morning.
05/802 PM.
For the Outer Waters, moderate to high confidence in current forecast. Through Sunday morning, high confidence in winds and seas remaining below Small Craft Advisory (SCA) levels, except for local gusts to 25 kt north of Point Sal this evening. Sunday afternoon through Monday, there is a 60-80% chance of SCA level winds. For Tuesday and Wednesday, high confidence in winds and seas remaining below SCA levels. On Thursday, there is a 30-50% chance of SCA level winds.
For the Inner Waters north of Point Sal, high confidence in winds and seas remaining below SCA levels through Thursday.
For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. Tonight through Wednesday, high confidence in winds and seas remaining below SCA levels. On Thursday, there is a 30-50% chance of SCA level winds across western sections.
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.
05/1140 AM.
Significant coastal impacts are expected across Southern California beaches this Labor Day weekend. A large southeast to south swell from Hurricane Marie will move into the coastal waters this weekend with swell heights of 5-7 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 boost that enhancement. As a result, high tides should exceed 7 feet by Monday. Adding large tides 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.
Ca, Coastal Flood Advisory in effect until 11 PM PDT Tuesday for zones 87-354-362-366. (See LAXCFWLOX). High Surf Advisory in effect until 11 PM PDT Tuesday for zones 87-354-362-366. (See LAXCFWLOX). Beach Hazards Statement in effect through Tuesday evening for zones 340-346-349-350. (See LAXCFWLOX). PZ, Small Craft Advisory in effect from 3 PM Sunday to 9 AM PDT Monday for zones 670-673-676. (See LAXMWWLOX).
