08/231 AM.
A significant southerly swell will bring hazardous surf conditions to the beaches through at least Tuesday. Isolated showers will continue at times through Tuesday. The combination of increasing heat and humidity across the area will cause moderate to major impacts, focused over the coasts and valleys Tuesday through at least Thursday.
(tdy-Thu), 08/231 AM.
Here are the top ten rainfall totals for this event:
PRELIMINARY PRECIPITATION TOTALS
.TOP RAINFALL AMOUNTS FROM ALL LOCAL AREAS OPIDS CAMP (LA COUNTY). . . . . , 1.86 STUNT RANCH (LA COUNTY). . . . . .. 1.58 CHILAO SOUTH (LA COUNTY). . . . . . 1.57 BEL AIR (LA COUNTY). . . . . . .. 1.56 CHILAO (LA COUNTY). . . . . . , 1.56 MONTE NIDO (LA COUNTY). . . . . , 1.53 BURBANK (KBUR) (LA COUNTY). . . . , 1.46 SEPULVEDA CYN AT MULH (LA COUNTY). . . 1.45 BEVERLY HILLS (LA COUNTY). . . . . 1.42 CRYSTAL LAKE (LA COUNTY). . . . . . 1.41
For more totals see RRMLOX: forecast.weather.gov/product.php?site=lox&issuedby=LOX&product=RRM
PWATs will reach 1.7 inches today as moisture from former hurricane Marie continues to feed into Srn CA. This will lead to a 10-20% chance of showers and thunderstorms across all four counties today. For Wednesday, a slight chance of showers and thunderstorms (10-15%) will continue over the northern VTA county mtns. There will be a 5% chance will over the rest of the mtn areas.
The main weather story for the next three days will be the heat and humidity. An upper high will migrate to the west and will end up over Needles by Thursday. Hgts will rise from 588 dam Monday evening to 596 dam Thursday. At the sfc there will be weak offshore flow this morning and Wednesday morning with only very weak onshore flow in the afternoon. Not enough offshore flow to create much of any canyon winds but enough to deprive the area of the cooling sea breeze. Thursday will see a some onshore trends which will serve to cool the csts some but the interior will continue to sizzle. The big additional problem will be the humidity which will be much higher than normal as PWATs will be near 1.5" which is .86" greater than normal.
The combination of hotter than normal temps and much higher than normal humidities has prompted the issuance of heat advisories for the Los Angeles County beaches and coastal valleys, and the Santa Monica Mountains today through Thursday. On Wednesday additional Heat Advisories go into effect for the Ventura County coasts and valleys, the Santa Clarita Valley, and all of Santa Barbara and San Luis Obispo Counties and are valid through Thursday evening.
There is 20-30 percent chc that humidities will rise to levels high enough to trigger heat warnings on Wednesday.
In addition to the daytime humidities the moisture will also keep overnight low temperatures well above normal with widespread 70s with even some 80s in the foothills).
The Central Coast will not be immune from this event as offshore flow on Wednesday will drive some temperatures all the way to 100 to 102 degrees and most areas will end up 20 degrees or more above normal.
(Fri-Mon), 08/231 AM.
Hgts should fall to about 592 dam on Friday while at the same time onshore flow increases both to the N and E. This should lead to 3 to 6 degrees of cooling for almost all of the area. PWATs fall as well but will still be above normal. If all of this comes to fruition there will be no need for any heat products. There is, however, a 20 percent chc that this cooling may be slower to develop and there will be a need for one more day of heat headlines.
The ridge flattens out over the weekend and onshore flow continues. Look for 3 to 6 degrees of cooling on Saturday which should bring most temps to a few degrees blo normal. Sunday's temps will be similar to Saturdays. PWATs should drop down to normal as well.
Onshore flow weakens some on Monday and this should lead to 1 or 2 degrees of warming.
08/1147z.
At 0832Z at KLAX, there was no marine layer. A surface inversion had a top near 1800 feet, with a temperature of 27 degrees C.
Low to moderate confidence in the Central Coast sites. There is a 40 percent chc of no dense fog at KSMX and a 40 percent chc of LIFR conds at KSBP through 16Z.
Good confidence in no low clouds for the rest of the sites.
There is a slight chance of showers and thunderstorms for all areas from 15Z to 00Z.
KLAX, Good confidence in TAF. There is a slight chance of -SHRA and a non-zero chance of -TSRA 15Z-00Z. Any showers could produce locally gusty winds and brief moderate to heavy rain. No significant east wind component expected.
KBUR, Good confidence in TAF. There is a slight chance of -SHRA and a non-zero chance of -TSRA 15Z-00Z. Any showers could produce locally gusty winds and brief moderate to heavy rain.
08/233 AM.
There will be a slight chance of thunderstorms over portions of the waters today, mainly in the western Santa Barbara Channel and northward.
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 night through Friday, SCA winds are likely much of the time, especially over the southern zones near and south of Point Conception.
For the Inner Waters north of Point Sal, there is a 60% chance of SCA winds Thursday afternoon through Friday.
For the Inner Waters south of Point Conception, localized areas of borderline SCA winds are likely this afternoon and evening, nearshore along the LA County coast and through the San Pedro Channel. The focus for SCA winds will shift to the western Santa Barbara Channel Thursday into the weekend.
A south swell is impacting the area, although beginning to subside. This swell may still cause increased currents and surges in vulnerable harbors. Breaking waves may impact some south facing harbor entrances, particularly for Ventura and Los Angeles Counties.
07/726 PM.
There is a slight chance of thunderstorms across the Los Angeles County beaches through this evening. Any thunderstorm that forms could produce local gusty and erratic winds and seas, brief heavy downpours, and dangerous cloud-to- surface lightning. Additional thunderstorm chances are expected early Tuesday morning through the afternoon hours, affecting mainly the Central Coast and Santa Barbara South Coast, but with a non-zero chance further south.
A south swell from tropical storm Marie is beginning to subside, but with continued coastal impacts likely through Tuesday. High surf will affect south- facing beaches of Ventura and Los Angeles counties, peaking at 4-7 feet with local sets to 8 feet through Tuesday afternoon. Very strong rip currents will continue as well. The highest surf is along Zuma Beach and the Long Beach area. HIGH SURF ADVISORIES remain in place for Los Angeles and Ventura Counties, with BEACH HAZARDS STATEMENTS 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, with the evening tides likely near or exceeding 7 feet. As the surf begins to diminish, the coastal flooding will subside somewhat.
Expect 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 times of high tide. Other areas of concern the next couple of days include Catalina Island, and Oxnard to Malibu (including the Pacific Coast Highway near 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 this evening for zones 87-354-362-366. (See LAXCFWLOX). High Surf Advisory in effect until 11 PM PDT this evening for zones 87-354-362-366. (See LAXCFWLOX). Beach Hazards Statement in effect through this evening for zones 340-346-349-350. (See LAXCFWLOX). Heat Advisory in effect from 10 AM this morning to 8 PM PDT Thursday for zones 362-366>373-548. (See LAXNPWLOX). PZ, NONE.
