07/1252 PM.
A significant southerly swell will cause hazardous surf conditions at the beaches through at least Tuesday. Isolated showers will continue at times through Tuesday. Heat will build across the region going forward, with moderate to major heat impacts focused over the coasts and valleys Tuesday through at least Thursday.
(tdy-Thu), 07/234 PM.
Now that the main rain event from Tropical System Marie is behind us, the focus of the forecast pivots to the the upcoming heat event. While remnants of Marie will remain well off the California Coast over the next few days, a ridge of high pressure will build into the region from the east over the next several days. Temperatures will trend upwards each day through Wednesday, when 500 mb heights and the light offshore winds will peak. For most areas Wednesday will be by far the warmest day of the event, most noticeably along the Central Coast including Santa Maria and San Luis Obispo, except the Santa Barbara South Coast may see the warmest temperatures on Thursday due to an increase in Sundowner winds in the area.
Heat Advisories are in effect Tuesday through Thursday for Los Angeles County beaches and coastal valleys, and the Santa Monica Mountains. Wednesday Heat Advisories are expanded to include the Ventura County coasts and valleys, the Santa Clarita Valley, and all of Santa Barbara and San Luis Obispo Counties. Widespread highs will peak in the 90s (including near some coasts) to low 100s. Due to Marie's influence on the area, humidity will be elevated which will significantly increase the HeatRisk and discomfort. The moisture will impact overnight low temperatures, which will remain very warm (widespread 70s with even some 80s in the foothills). Mid and high cloud coverage will serve to moderate heat impacts at times, and the overall event will be relatively short compared to other heatwaves we have seen so far this summer. This heat may feel comparable or even slightly worse to recent heat waves, especially near the coast. Those working or recreating outdoors as well as those without air conditioning are advised to follow the forecast, stay hydrated, and seek cooling centers when possible. There is around a 20-30 percent chance of the Heat Advisories being upgraded to Extreme Heat Warnings on Wednesday. This will depend some on the anticipated cloud coverage. The coastal areas along the Central Coast are of particular concern on Wednesday, where temperatures may reach 100 degrees or higher for some locations (20+ degrees above normal).
Tropical Storm Marie is currently centered 750 miles southwest of Los Angeles, continuing its northwest movement well offshore of southern California. Even so, moisture and south swells remain in the area. There is an ongoing, significant hazard across south facing beaches, with strong and potentially deadly rip currents (see coastal hazards for details). As for more rain, there is a slight chance (5-15%) of thunderstorms focused over LA and Ventura County through this afternoon, and then tomorrow focused over Ventura Santa Barbara Counties and the Central Coast (and coastal waters). This is due to the very high PWATs brought into the region by Marie, combined with any sources of lift. Minor scattered shower are possible through Tuesday. Then by Wednesday, shower and thunderstorm activity will likely become confined to the highest mountains as the strengthening ridge caps and slightly dries out mid-levels of the atmosphere.
(Fri-Mon), 07/226 PM.
There is the potential for Heat Advisories to be extended on Friday, however there is high uncertainty for this time period. Ridging is favored to continue for the area on Friday, but 500 mb heights will not be as high as previously, and onshore flow will be stronger thus increasing the cooling seabreeze. By the weekend, near normal temperatures appear likely. Troughing off the coast may reestablish at times, keeping the door open for additional tropical moisture to shuttle into southwest California.
07/1157z.
At 08Z at KLAX, there was no marine layer with a weak surface inversion.
Moderate confidence for KSBA and north and low confidence elsewhere including the desert TAFs. There is a 20-40 percent chance of SHRA at times through at least 00Z for LA County TAFs, highest KLAX/KSMO and KBUR to KLGB. There is a 5-10 percent chance of a thunderstorm between 20Z-00Z.
50 percent chance that VLIFR cigs/vsbys continue for KWJF through 15Z-16Z. There is a 20 percent chance of brief IFR or lower cigs/vsbys for KSMX through 16Z.
KLAX, Low confidence in TAF. VSBY may lower 3sm in SHRA. Any east wind component should remain below 5 kts.
KBUR, Low confidence in the 00Z TAF. VSBY may lower to 2SM during SHRA.
07/646 AM.
For the waters south of the Channel Islands, there is a slight chance of thunderstorms through this evening. Any thunderstorm that storms could produce local gusty and erractic Gale Force winds and seas, brief heavy downpours, and dangerous cloud-to- surface lightning.
For the Outer Waters, below Small Craft Advisory (SCA) level winds and seas are expected into Wednesday, except for local advisory level gusts around Point Conception each afternoon and evening. Wednesday evening into at least late next week SCA winds are likely much of the time.
For the Inner Waters north of Point Sal, there is a 30% chance of SCA level winds Wednesday afternoon/eve and a 60% chance for Thursday. Increasing potential for SCA winds Friday into the weekend.
For the Inner Waters south of Point Conception, localized pockets of borderline SCA winds are likely Tuesday afternoon and evening. Winds are likely to be a bit stronger and more widespread on Wednesday with a 60% chance of advisories being issued. Focus for SCA winds shifts towards the western portion of the Santa Barbara Channel Thursday into the weekend.
Tropical moisture will continue to stream over the coastal waters into Tuesday, bringing a slight chance of showers. Besides today (mentioned above), a thunderstorm cannot be ruled out across the outer waters on Tuesday.
A large south swell is impacting the area, causing increased currents and surges in the vulnerable harbors. Breaking waves may impact south harbor entrances, particularly for Ventura and Los Angeles Counties (observed at Ventura Harbor).
07/642 AM.
There is a slight chance of thunderstorms across Ventura and Los Angeles County beaches through this evening. Any thunderstorm that storms could produce local gusty and erractic winds and seas, brief heavy downpours, and dangerous cloud-to- surface lightning.
Significant coastal impacts are expected across Southern California beaches through at least Tuesday. A large southeast to south swell from Hurricane Marie has moved into 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 12 feet through today. Potentially life threatening rip currents will continue as well. The highest surf is near Zuma and Malibu Beach as well as Long Beach. 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.
Moderate coastal flooding has occurred and will continue around high tides for south facing shores. The actual observed tides have been running about 6 inches above predictions for sometime now. The south swell will likely boost that enhancement. As a result, high tides are expected to reach exceed 7 feet during the evening high tide.
Expect significant beach erosion, flooded sandy beach areas, bike paths, and parking lots, as well as low-lying roads. Of particular concern will be the Alamitos Peninsula area in Long Beach where coastal flooding will potentially cause local damage to structures near time of high tide later today, Other areas of concern the next couple of days include Catalina Island, 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, Heat Advisory in effect from 10 AM Wednesday to 8 PM PDT Thursday for zones 38-88-340>358-374-375. (See LAXNPWLOX). 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). Heat Advisory in effect from 10 AM Tuesday to 8 PM PDT Thursday for zones 362-366>373-548. (See LAXNPWLOX). PZ, NONE.
