15/135 PM.
Seasonal June conditions will continue, with a stronger onshore flow developing late week into this weekend that will be capable of pushing night through morning low clouds and fog further inland. Near to slightly above normal temperatures will continue through Tuesday, with minor afternoon heat impacts, before cooling down during the second half of this week into this weekend. There is then increasing confidence of more impactful heat building next week.
(tdy-Thu), 15/103 PM.
The area remains under very weak synoptic flow in between two high pressure circulations, one to the southeast over northern Mexico and the other to the northwest over the eastern Pacific, off the OR and NorCal coast. Overall heights have increased slightly over the area and the marine layer deepened slightly over the last 24 hours. This change should yield afternoon temperatures today and Tuesday similar to yesterday to a few degrees warmer. Although, temperature readings at midday were reading a few degrees cooler compared to midday yesterday for most coastal areas, with the exception of warmer readings across Ventura County and Northern LA County. Overall, temperatures today and Tuesday should run up to 5-10 degrees above normal for most areas. The marine layer will continue to protect coastal areas from the heat with highs only in the 70s to near 80, including inland coastal sections of LA County, and 90s to 100 for the inland and interior valley areas.
Afternoon temperatures today and Tuesday, combined with continued higher humidity (RH>55) and sunny skies will lead to widespread minor and locally moderate heat impacts for the hotter inland areas, including areas like the San Fernando Valley. So, heat stress will be an impact in the afternoons. Good cooling trends in the evening and especially overnight should limit overall impacts. However, those sensitive to the heat may want to consider avoiding peak heat of the day, hydrate often, and take breaks from outdoor activities to find cooler shaded areas or AC.
Through Tuesday ridging and offshore trends will likely lead to earlier burn off of low clouds and fog, except for possibly some west facing beaches of Los Angeles and Ventura County. Low clouds will struggle to penetrate into coastal valleys and fog may become more common where low clouds do occur albeit with limited concern for dense fog given continued onshore flow and only weak ridging/height rises aloft.
A slow-developing trough offshore over the East Pacific will begin building into the region by Thursday, and will initiate moderate cooling trends away from the coast, reducing heat risk even to warmer interior areas. Although the trough pushes more into the region late-week, initial cooling is expected to begin Wednesday. Night-to-morning low clouds may begin to expand further into the coastal valleys by Wednesday morning as model guidance shows strengthening onshore flow heading into the second half of the week.
(Fri-Mon), 15/130 PM.
Friday into this weekend, the coastal trough will continue to produce deep westerly to southwesterly flow over much of CA and carry the cooling trend through at least the start of the weekend, with the most notable cooling away from the coast. This will significantly reduce heat risk even to warmer interior areas and latest guidance has afternoon high temperatures up to 5-10 degrees below normal Friday through the weekend. Night-to-morning low clouds will likely continue to push further into the coastal valleys and possibly some lower foothills through the start of the weekend. There will also be increased odds for some drizzle within the marine layer each morning.
With the stronger onshore push late-week into this week, this will support gusty onshore to northwest winds nearing advisory levels for the interior, possibly extending to southwest Santa Barbara. Strongest winds will be across the Antelope Valley, with guidance showing winds peaking Friday near advisory criteria. There may be a period of enhanced fire weather concern on one or both of those transition days for far interior areas and maybe especially at high elevations, which would be situated above the expanding marine layer influence.
Looking further out, there is increasing confidence of a more significant warming trend beginning early next week and peaking toward the middle of the week with strong high pressure developing across much of the southwest CONUS. Temperatures are forecast to warm back to around the level they are now beginning around Tuesday and then warm further beyond Tuesday, witch will increase the heat risk and bring potential heat alerts to many inland valleys and basins.
15/2206z.
High confidence in KVNY KPMD & KWJF.
Low to moderate confidence in remaining TAFs. Timing of CIG/VSBY restrictions may be off 3 hours and flight minimums by one category. There is a 10-20% chance stratus reaches KBUR and KVNY between 12-16Z Tuesday.
KLAX, Moderate confidence in TAF. Marine stratus returns late this evening between 5-8Z. No significant east wind component expected.
15/232 PM.
Moderate to high confidence in current forecast. Wind gusts around 21 kts during the afternoon and evening timeframe across the Santa Barbara Channel, Santa Monica Basin, and nearshore Los Angeles Harbor into the San Pedro Channel. A Small Craft Advisory has been issued for waters south of Point Sal to San Mateo Point through 11 PM.
15/237 PM.
A couple of long period southerly swells (14 seconds and 18 seconds) will continue to affect the coastal waters through at least Wednesday. A Beach Hazard Statement is in effect through Wednesday evening due to elevated surf of 3 to 6 feet on south- facing beaches of Ventura County Beaches, Malibu Coast, Los Angeles County Beaches, and portions of the Southern Santa Barbara County Beaches.
Evening tides of 7.2 to 7.7 ft are predicted through Tuesday night. The combination of the unusually high tides with elevated surf could result in minor to locally moderate coastal flooding along south exposed coasts, especially near Malibu and Long Beach. In addition, there is along potential for sneaker waves. Stay tuned for updates and refer to CFWLOX for additional details.
Ca, Beach Hazards Statement in effect through late Wednesday night for zones 349-350-354-362-366. (See LAXCFWLOX). Coastal Flood Advisory in effect until 2 AM PDT Tuesday for zone 362. (See LAXCFWLOX). PZ, NONE.
