04/122 PM.
A major and long lasting heat wave is expected to persist through at least Thursday with dangerously hot temperatures. Friday into Sunday temperatures will trend cooler each day and there is a small chance of showers and thunderstorms due to mositure from distant Hurricane Rachel.
(Sun-Wed), 04/225 PM.
Extreme Heat will continue for much of the area through at least Thursday. High pressure will continue over the area and surface pressure gradients will remain predominantly offshore. A few calender day temperature records may be broken each day through Thursday. Highs will be widespread in the 90s to around 105 for many valleys and coasts south of Point Conception, which is about 15 to 27 degrees above normal for this time of year. Highs in the 90s for the mountains and deserts are closer to normal (about 10-15 degrees above normal).
The immediate coast across Los Angeles and Ventura Counties will see a small cooling trend going forward due to a increase in the sea breeze as a result in small weakening of the offshore flow south of Point Concepton. Overnight lows will remain warm through Tuesday night, mostly in the upper 60s to mid 70s, except even 80s in some mountains and foothills. Tuesday night the increase in afternoon onshore flow will allow temperature to fall by a few more degrees overnight.
Offshore winds along the Central Coast Wednesday and Thursday will make 100+ degrees possible for San Luis Obispo and a peak in temperatures for all of the coastal areas, and thus the heat Advisory for the Central Coast has been extended through Thursday. Additionally the forecast zone directly adjacent to the coast has been added into the Heat Advisory for Wednesday and Thursday, as the easterly winds are expected to result in very warm conditions all the way to the beach.
(Thu-Sun), 04/229 PM.
As mentioned in the short term, Thursday will be another hot day, with Extreme Heat Warnings and Advisories in place for much of the area. Temperatures will peak during the Wednesday/Thursday time period for the Central Coast. Temperatures will be very similar each day through Thursday for areas south of Point Conception, away form the immediate coast. Areas right along the ocean will see impacts of a tepidly strengthening sea breeze each day and cool by a few degrees each day. By Thursday, expect highs to cool to between 82 to 90 degrees right at the coast south of Point Conception. There is a 20-30% chance that at least some heat advisories will be needed on Friday. More significant and widespread cooling is expected Saturday and continuing into early the next week. Recent model trends are indicating at least a 20-30% chance of some showers for the weekend based on the latest ensemble tracks of Hurricane Rachel. Some increasing swells from Rachel are also expected starting Tuesday.
05/0104z.
At 0040Z at KLAX, the marine layer was 500 ft deep. The top of the inversion was at 900 ft with a temperature of 31 deg C. High confidence in VFR TAFs for all sites except for KSBP/KSMX. Chc of V/LIFR conds between 05/08Z-16Z: KSBP (15%) & KSMX (30%).
KLAX, High confidence in VFR TAF. Good confidence that any east wind component will remain below 7-8 kts after 04/19Z.
KBUR, High confidence in VFR TAF. No wind issues expected.
04/122 PM.
Generally quiet conditions 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.
Night through morning Dense fog may affect portions of the coastal waters west of the Channel islands and Point Conception through Thursday.
04/122 PM.
Quiet conditions are expected through the weekend, aside from the heat. Southerly swell from Hurricane Rachel will have impacts for the LA/VTA coastline including Catalina Island. A beach hazard Statement has been issued starting 4 PM Tuesday through 11 PM Friday. An upgrade to a Coastal Flood Advisory and/or High Surf Advisory may be needed with future updates. These products will likely need to be extended into the weekend. Refer to CFWLOX for main details.
Initially, the swell direction will be SE (150-160) targeting areas like Long Beach and Catalina island Tuesday and Wednesday. As Rachel continues westward, the swell direction will becoming more southerly (170-190) later Wednesday into Friday targeting areas like Zuma. Unlike previous events, morning and evening tides will be similar in height ranging 6.5 - 7.0 ft.
Outlook (Saturday into early next week):
A combination of long period southerly and westerly swells will impact our coastline into at least early next week. For the weekend, the main swell direction will remain more SW around 200 degrees near 15 seconds. Evening tides will decrease by a bit more than 0.5 ft but morning tides will increase a bit to 7.2 ft. This will result in continued elevated surf & coastal flooding concerns targeting areas from the Palo Verdes Peninsula to Ventura.
Super Typhoon Choi-Wan will continue moving north and will generate a strong, long-period W-NW swell which will arrive to the Central Coast the following Sunday or Monday (October 11/12). Will need to monitor this for high surf and coastal flooding potential.
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 Friday evening 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.
