06/1252 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. 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-Fri), 06/119 PM.
The bad news is strong high pressure aloft continues across the entire West Coast, generating dangerously hot temperatures during the day and in many areas very warm overnight temperatures as well. The good news is that onshore flow is slowly returning and most areas (not the Central Coast) will see at least a 1-3 degree cooling trend through the end of the week. Coastal areas have already felt this today where highs peaked 3-6 degrees degrees cooler than yesterday. However, it looks like any cooling tomorrow will still be confined to the coastal areas south of Pt Conception while valleys and other interior areas will see little or no change. And for the Central Coast, a light northeast flow aloft is expected Wednesday that will create some downslope warming off the Santa Lucias that should actually create 3-6 degrees of warming. All previously issued Heat Warnings and Advisories remain in effect through at least Thursday, though it's possible some coastal areas could drop off after Wednesday.
A significant cooling trend for all areas is expected to begin Friday. Highs will still be 5-10 degrees above normal but well below criteria for additional heat products.
(Sat-Tue), 06/143 PM.
The entire West coast will see a very quick reversal to below normal temperatures Sunday through Tuesday as a cold low pressure system drops south out of Canada. At the same time, there is an increasing number of model solutions showing remnant moisture and energy from Rachel moving up into southern California. Showers have been in the forecast during this period for some time but given the latest forecast track showing the remnants of Rachel moving a little farther north than before, and potentially a 550dam low arriving around the same time Sunday or Monday, there is at least a 5-10% chance of thunderstorms either or both of those days. By Monday, high temperatures will be mostly in the 70s, 5-15 degrees below normal.
06/1701z.
At 1603Z at KLAX, there was no marine layer. There was a sfc based inversion with a top at 1800 ft and a temp of 29 C.
High confidence in VFR TAFs for KPRB, KSBA, KOXR, KCMA, KBUR, KVNY, KPMD, & KWJF, with a less than 10% chance LIFR-IFR conds for immediate coastal sites from 14Z-17Z.
Moderate to high confidence in TAFs for remaining coastal sites. 15% chance for VFR conds to prevail at KSMX/KSBP. 20% chance for brief LIFR-IFR conds 13Z-17Z at KLAX, KLGB, & KSMO.
KLAX, High confidence in TAF. 15% chance for LIFR-IFR (004-008) 13Z-17Z. Good confidence that any east wind component will be AOB 6kt.
KBUR, High confidence in VFR TAF.
06/134 PM.
Relatively quiet conditions expected across the coastal waters through Friday. Localized Small Craft Advisory (SCA) gusts may occur each afternoon and evening between Point Conception and San Nicolas Island. Additionally, a short lived SCA has been issued for the northern portion of the outer waters Wednesday afternoon through late evening for increasing northwest winds. Night through morning dense fog may affect portions of the coastal waters adjacent to the Central Coast and south to San Nicolas Island.
Increasing west to northwest winds and seas (10+ foot off Central Coast) are likely this weekend through at least Monday. Additionally, remnant moisture from current Hurricane Rachel will bring a chance of showers and a very small chance of thunderstorms to the waters late this weekend into early next week, best chances south of Point Concpetion.
06/133 PM.
Southerly swell from Hurricane Rachel will impact the Los Angeles and Ventura Counties coastline including Catalina Island starting this evening. A Beach Hazard Statement has been issued starting 4 PM today and will transition to an a Coastal Flood Advisory early Wednesday morning through Friday.
Initially, the swell direction will be more from the south-southeast (150-160) tonight, turning more southerly (170-190) Wednesday through Friday. Unlike previous events, morning and evening high tides will be similar in height ranging 6.5 to 7.0 ft. Coastal flooding impacts are anticipated to be greatest for Long Beach (especially Alamitos Peninsula), Catalina Island (while the swell is SSE), and the Malibu/Zuma Beach coast.
Saturday into early next week, tides will be very high (7+ feet) and a combination of multiple longer and shorter period swells from the south and west are expected to impact our coastline over the weekend into at least early next week. Plenty of uncertainty exists regarding the timing and magnitudes of these swells, thus there is lots of uncertainty in exact coastal flooding and surf impacts. However, there is a risk for significant impacts.
Please continue to monitor the forecast.
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 through late tonight 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, Small Craft Advisory in effect from 3 PM Wednesday to 3 AM PDT Thursday for zone 670. (See LAXMWWLOX).
