05/1246 PM.
A major and long lasting heat wave will to persist through at least Thursday with dangerously high temperatures, though some cooling is expected near the coast the next few days. Friday into Sunday, temperatures will trend cooler each day and there is a small chance of showers and thunderstorms due to moisture from Hurricane Rachel.
(tdy-Thu), 05/158 PM.
It was another very hot day today with many areas over 100, particularly in LA and Ventura Counties. However, a slight onshore trend developed and was just enough to knock down highs at the beaches and some inland coastal areas. For example, Camarillo reached a high of 99 just before noon, but by 1pm the temperature was "only" 90, which was 9 degrees cooler than yesterday at this time. Meanwhile, it was another 102 in Downtown LA which is the 4th day of 100 or higher there (which is the longest such stretch in October, and ties the record for any time of year).
It's going to remain hot through the rest of the week but as we noticed today there will be some areas near the immediate coast where the sea breeze pushes, resulting in 1-5 degrees of cooling. One exception to that may be along the Central Coast where models are showing a light northeast flow off the Santa Lucia range that should push temps into the 90s Tue and Wed. For inland areas temperature trends will likely remain flat or possibly 1-2 degrees of cooling for areas below 500 feet elevation as high pressure aloft remains quite strong and gradients remain 1-3mb offshore.
(Fri-Mon), 05/207 PM.
High pressure will start to break down by around Friday but highs will still be 6-12 degrees warmer than normal with warmer valley highs around 100 and Downtown in the low to mid 90s.
A more pronounced cooling trend is expected by Sat as high pressure weakens and a weak upper level low drops down the coast of California. That upper low may pull up moisture from Rachel, depending on Rachel's track, so there is a chance of showers by Sunday, mainly LA County.
05/1837z.
At 1820Z at KLAX, there was no marine layer or inversion.
Moderate confidence in TAFs for KSMX with a 40 percent chc no clouds developing tonight, at KSBP there is a 15 percent chc of VLIFR conds for a few hours tonight into tomorrow morning.
High confidence in the remainder of the CAVU TAFs.
KLAX, High confidence in CAVU TAF. East wind of 5-7 kts are expected until 19-20Z and then will switch to westerly.
KBUR, High confidence in CAVU TAF.
05/245 PM.
Generally quiet conditions are expected across the coastal waters through the forecast period. Localized Small Craft Advisory (SCA) gusts may occur each afternoon and evening between Point Conception and San Nicolas Island, off the coast of Point Dume, and across the San Pedro Channel. Winds over the outer waters will begin to increase Wednesday night through Friday with a 30% chance of SCA gusts at times, mainly during the afternoon to evening hours.
Night through morning dense fog may affect portions of the coastal waters west of the Channel islands and Point Conception through Thursday.
05/244 PM.
Southerly swell from Hurricane Rachel will impact the Los Angeles and Ventura Counties coastline including Catalina Island starting late Tuesday. A Beach Hazard Statement has been issued starting 4 PM Tuesday and will transition to an a Coastal Flood Advisory early Wednesday morning through Friday.
Initially, the swell direction will be SE (150-160) Tuesday becoming more southerly (170-190) Wednesday and Friday. As Rachel continues westward, the swell direction will becoming more southerly (170-190) by Thursday and Friday. Unlike previous events, morning and evening high tides will be similar in height ranging 6.5 - 7.0 ft. Coastal flooding impacts are anticipated to be greatest for Long Beach, Catalina Island, and Malibu/Zuma Beach.
Saturday into early next week, tides will be very high (7+ feet) and a combination of long period southerly and westerly swells are expected to impact our coastline over the weekend into at least early next week. Some uncertainty in exact coastal flooding and surf impacts, but there is a risk for significant impacts. Please continue to monitor the forecast going forward.
Ca, Extreme Heat Warning in effect until 8 PM PDT Thursday for zones 38-87-88-349>358-362-366>375-548-550. (See LAXNPWLOX). Beach Hazards Statement in effect from Tuesday afternoon through late Tuesday night for zones 87-354-362-366. (See LAXCFWLOX). Coastal Flood Advisory in effect from 6 AM Wednesday to 11 PM PDT Friday for zones 87-354-362-366. (See LAXCFWLOX). Heat Advisory in effect from 10 AM Wednesday to 8 PM PDT Thursday for zones 340-346. (See LAXNPWLOX). Heat Advisory in effect until 8 PM PDT Thursday for zones 341>345-347-348. (See LAXNPWLOX). PZ, NONE.
