29/736 PM.
Temperatures will become dangerously hot in many areas Friday through the upcoming weekend, as the next heat wave arrives. Some cooling is expected next week, though temperatures will remain above normal. Dangerous surf conditions are expected at area beaches this week into this weekend, as a result of swells from a distant tropical cyclone located west of Mexico.
(Wed-Sat), 29/1014 PM.
***UPDATE***
High temperatures today were nearly the same as yesterday, with about 2-4 degrees of warming over the interior. Marine layer clouds limited warming near the coasts, especially along the Central Coast. Over the next few days, high pressure will build over southern California, with heights peaking around 599-600 DAM Friday into Saturday, supporting widespread warming over the next few days. This should also limit marine layer clouds and patchy fog to areas closest to the coasts, and we could see some dense fog developing by Saturday morning as the LAX-DAG onshore pressure gradient falls to around 1 mb. Sundowner winds are expected to reoccur each night, possibly reaching advisory levels Friday evening and Saturday evening. Otherwise, the current forecast looks on track.
***From Previous Discussion***
Temperatures will remain seasonably warm today and tomorrow before high pressure over Arizona expands west Friday and through the weekend. Models have been very consistent over the last week showing 500mb heights rising to 600dam (at or above the 99th percentile) over the interior California deserts by Saturday and possibly as far west as the coast. The extreme pressure being exerted from aloft will force temperatures at the surface to rise to around 10 degrees above normal in many areas, resulting in significant heat stress, especially in areas that have limited or no access to cooling sources. Current forecast highs are near or exceeding record temperatures in many areas, especially Friday and Saturday. Temperatures along the Central Coast are cooler compared to other areas but even there forecasts are close to or exceeding daily records.
One positive aspect is that humidities have been decreasing as tropical moisture remains east and south of the area. This is allowing overnight temperatures overnight to cool a few degrees, providing some relief. However models are strongly suggesting increasing moisture aloft later this week and weekend during the peak of the heat wave, which will further exacerbate the heat stress over the area.
A large south swell from Tropical Cyclone Genevieve will further enhance large wave and potentially deadly rip currents for some area beaches.
(Sun-Wed), 29/223 PM.
A slow cooling trend is expected to begin Sunday, though temperatures will still be 5-10 degrees above normal and increasing moisture aloft will limit overnight cooling and keep humidities higher than normal. And in addition, high pressure aloft will continue to dominate the weather pattern along the West Coast all of next week, meaning highs will remain above normal for the foreseeable future. Heat hazards may continue into next week.
30/0207z.
At 23Z at KLAX, the marine layer was 800 feet deep. The top of the inversion was 2400 feet with a temperature of 26 degrees Celsius.
For 00Z TAFs, moderate to high confidence. For TAFs near the coast and in the coastal valleys, CIG/VSBY restrictions with night through morning fog may vary from forecasts by 3 hours in timing and by 1 flight category. High confidence in VFR TAFs for interior sites.
KLAX, Moderate confidence in TAF. There is a 40% chance for onset and dissipation of flight restrictions to vary by up to 3 hours from the current forecast. There is a 40% chance for minimum flight category to vary by up to 1 level from current forecast. No significant easterly wind component is anticipated.
KBUR, Moderate confidence in TAF. There is a 40% chance cigs fail to reach the TAF site Thursday AM.
29/748 PM.
For the Outer Waters, Small Craft Advisory (SCA) winds and seas will occur through the remainder of this week and into this weekend, before subsiding early next week.
For the Inner Waters north of Point Sal, there is an 80% chance for SCA winds each afternoon and evening through Saturday. For the Inner Waters south of Point Conception, there is 40% chance of SCA winds each afternoon and evening through this weekend over the western one-third of the Santa Barbara Channel.
Additionally seas of 8-12 feet will impact the outer waters into this weekend, owing to a long-period southerly swell from a distant tropical cyclone, combining with shorter-period northwesterly swell/wind waves resulting from the moderate to strong NW winds. As a result, steep, hazardous seas will be common over especially the outer waters, extending to the coast especially for the Central Coast.
29/743 PM.
Hurricane Genevieve is generating long period S-SE swells that will affect the beaches for the remainder of this week into this weekend. A High Surf Advisory is in effect for the south facing beaches of LA and Ventura Counties through Saturday afternoon. Very strong, severe rip currents have been reported from some area beaches, with a risk of strong long-shore currents and sneaker waves. Use extra caution if you are at the beach, and be sure to ask lifeguards if and where it is safe to swim.
Please reference the Coastal Hazard Message for details on High Surf and Coastal Flood Advisories, as well as Beach Hazards Statements. Dangerous rip currents will be of particular concern this weekend.
Ca, Extreme Heat Warning in effect from 10 AM Friday to 8 PM PDT Sunday for zones 38-88-343>345-351>353-355>358-368>376-378-379-548. (See LAXNPWLOX). Coastal Flood Advisory in effect until 3 AM PDT Saturday for zones 87-354-362-366. (See LAXCFWLOX). High Surf Advisory in effect until 5 PM PDT Saturday for zones 87-354-362-366. (See LAXCFWLOX). Beach Hazards Statement in effect through Saturday afternoon for zones 340-346-349-350-356. (See LAXCFWLOX). Heat Advisory in effect from 10 AM Friday to 8 PM PDT Sunday for zones 341-342-347>350-354-362-366-367-377. (See LAXNPWLOX). Heat Advisory in effect from 10 AM Thursday to 10 AM PDT Friday for zones 378-379. (See LAXNPWLOX). Heat Advisory in effect from 10 AM Thursday to 8 PM PDT Sunday for zone 380. (See LAXNPWLOX). Extreme Heat Warning in effect from 10 AM Thursday to 8 PM PDT Sunday for zones 381>383. (See LAXNPWLOX). PZ, Small Craft Advisory in effect until 3 AM PDT Thursday for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect from 3 PM Thursday to 3 AM PDT Friday for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect until 5 AM PDT Monday for zones 670-673-676. (See LAXMWWLOX).
