07/328 AM.
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 through the next several days, with moderate to major heat impacts for the coasts and valleys Tuesday through Thursday.
(tdy-Wed), 07/553 AM.
***UPDATE***
We have added a a slight chance (5-15%) of thunderstorms to much of LA County (including LA City), the northern Ventura mountains and the adjacent waters as a thunderstorm has already developed well offshore and we expect the environment will only become more conducive by midday for isolated thunderstorms. Discussion below has been updated accordingly.
***From Previous Discussion***
Early this morning Tropical Storm Marie was was centered 760 miles SSW of Los Angeles, continuing its northwest trek. This track will maintain its position well away from southern California, although the associated tropical moisture and southerly swells will continue to affect the area. The south swells have created an ongoing, significant hazard at area beaches, especially the exposed south facing beaches, with strong and potentially deadly rip currents (see coastal hazards for details).
Rapidly increasing heat concerns are the main story over land with moderate to major heat risk and associated heat products becoming likely for many areas, especially coastal valleys to coast by Wednesday.
The main player for the rapid changes is a ridge bulging in from the east with 500 mb heights steadily increasing from mid 580s to mid to upper 590s by Wednesday. Weak offshore flow from the north and possibly east by Wednesday will delay and weaken the sea breeze influence, allowing the significant heat to build towards the coast. Widespread highs in the 90s (including near some coasts) to low 100s will in its own right be hot. However the potential for extreme humidity (for Southern California) from incredibly high precipitable waters of 1.5-2 inches, well above normal ocean temperatures, and even recent or upcoming rainfall will make it MUCH more miserable outside and also keep temperature the 70s and 80s well into the evening and even overnight for some areas. This heat may feel comparable or even slightly worse to recent heat waves, especially near the coast. Spread the word to prepare for yet another potential heat wave mid week. Fortunately this one may be relatively short lived (see long term discussion).
The shower activity that was continuing to stream into LA County from the southwest early this morning will likely continue at times through at least this afternoon. There is also a 5-15 percent chance of a thunderstorm focused across much of LA County (including LA City), northern Ventura County Mountains and the adjacent waters as mid-level lapse rates near an impressive 7 deg C/km with moderate elevated instability across LA County with an emphasis on the northeast portion (mountains and desert). The main threats with these tropical-like thunderstorms is cloud-to-ground lightning, and brief heavy downpours. Enhanced southerly flow due to the sandwiching effect of the building ridge and the remnants passing well to our west will likely support at least sporadic showers continuing or reforming into tonight and especially into Tuesday. The activity may focused across LA or Ventura County and then shift north while possibly expanding in coverage. While moderate showers will be possible within this activity, it should mostly be on the move, greatly limiting flood concerns.
Isolated shower and thunderstorm activity will likely become confined to the highest mountains by Wednesday as the strengthening ridge caps and slightly dries out mid-levels of the atmosphere.
(Thu-Sun), 07/536 AM.
Upper level ridge of high pressure expected to remain strong over the area on Thursday, then weaken some on Friday. During this time, pressure gradients will likely be weakly offshore to the north and weakly onshore to the east, resulting in a continuation of hot temperatures with associated heat impacts across much of the region on Thursday, with a slight cool-down possible by Friday. There is also the potential for some weak to moderate sundowner wind activity across southern Santa Barbara county each evening on Thursday and Friday.
The position of the ridge by Thursday may be favorable for some monsoon moisture or injection of tropical moisture from the south. So it will likely continue to be quite humid with weak morning offshore flow potentially delaying the sea breeze. This type of pattern could support isolated showers or thunderstorms focused across the interior.
Below normal confidence Friday into next weekend as the ridge may break down pretty quickly (30 percent chance) or be somewhat stubborn. Either way it does look somewhat likely that 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, 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 until 9 AM PDT this morning for zones 670-673-676. (See LAXMWWLOX).
