09/206 AM.
Extreme heat and humidity will peak Today and Thursday with a high risk for heat illness. Isolated showers and thunderstorms are possible today as well, mainly over the mountains. Elevated surf and coastal flooding will linger into Thursday, but decrease in severity. Cooler and more normal conditions likely by Saturday.
(tdy-Fri), 09/206 AM.
The next two days (Today and Thu) will feature very dangerous and unusual heat. High pressure over AZ will bring 596 dam hgts to Srn CA today and 595 dam hgts Thu. SFC high pressure to the NE will bring 2-3 mb of offshore flow this morning both from the N and E. This one two punch will bring 3 to 6 locally 8 degrees of warming to areas south of Pt Conception and a whopping 10 to 15 degrees north. This will lead to max temps of mid to upper 80s at the beaches, 90s across the rest of the csts and 100 to 108 degree temps for the vlys. The big kicker for this two day event will be the humidity which will be much higher than normal due to the remnants of Hurricane Marine and the much warmer than normal sea sfc temps. This extra humidity will make the temps feel much worse and will lessen the bodies cooling abilities. This humidity as well as the strong inversion will also lead to much warmer than normal overnight lows which will make heat recovery difficult for people without Air Conditioning.
Extreme Heat Warnings are in effect today and Thursday. The added humidity really make this heat event much more dangerous than previous ones. All residents should limit your outdoor activities during the afternoon, seek air conditioned spaces, and take lots of breaks.
One more addition to these unusual weather days will be another round of potential TSTMs. There will be enough lingering mid level moisture that when combined with afternoon sunshine could be enough to cook off some mtn TSTMs that could drift off and into the interior vlys.
The upper high weakens on Friday and hgts fall to about 590 dam. In addition there will be good onshore trends both to the N and E. The humidities will also decrease. Max temps should fall 3 to 6 locally 8 degrees and the decrease in humidities will make it much less sticky. This cooling should be enough to end the Warning Level heat, but some heat advisories may still be necessary.
(Sat-Tue), 09/206 AM.
Much more benign weather is on tap for the xtnd period. At the upper levels fairly flat flow will set up over the state through Monday with hgts near 588 dam. Starting Tuesday the flow tilts to the SW-NE and Srn CA finds itself between a PACNW low and a TX high. At the sfc there will be weak to moderate onshore flow to the east and weak morning offshore flow turning weakly onshore in the afternoon flow in the N/S direction.
The very warm sea sfc temps will inhibit low cloud formation but its likely some patchy low clouds will develop south of Pt Conception. The Central Coast will likely have better stratus coverage in the mornings.
Look for another 3 to 6 degrees of cooling and Saturday and another noticeable decrease in humidities. Most max temps will be a few degrees blo normal. Most csts/vlys south of Pt Conception will cool another 1 or 2 degrees on Sunday while a little increase in offshore flow across the Central Coast will bring 2 to 3 degrees of warming. Not much change slated for Monday with some additional cooling slated for Tuesday.
09/0908z.
At 0822Z at KLAX, there was no marine layer nor inversion.
High confidence in non-coastal TAFs.
Low confidence in TAFs for KSMX (40 percent chc of no low clouds) and KSBP (40 percent chc of LIFR conds 12Z-15Z).
Moderate confidence in the rest of the coastal TAFs with a 25 percent chc of IFR conds 12Z-15Z)
KLAX, Moderate confidence in TAF. There is a 25% chance of BKN008-012 conds 12Z-15Z. No significant east wind component expected.
KBUR, High Confidence in TAF.
09/133 AM.
There is a very small (but non-zero) chance of thunderstorms over the waters on today. Any thunderstorm that forms could produce local gale force and erratic winds, brief heavy downpours, and dangerous cloud-to- ground lightning.
Moderate confidence in winds and seas increasing to Small Craft Advisory (SCA) levels through this morning, focused south and west of Point Sal and continuing through the weekend. Moderate confidence in winds expanding across all Outer Waters by this afternoon at the earliest. Better confidence in winds increasing to SCA levels by Thursday afternoon. Winds, and at times seas, will likely exceed SCA levels into early next week, with a 20-30% chance of Gale Force winds Thursday evening, and again on Sunday.
Across the nearshore waters along the Central Coast, winds will locally reach SCA levels today, with more expansive gusty winds Thursday into early next week, when SCAs will likely be issued.
South of Point Conception, moderate confidence in SCA winds across the western half of the Santa Barbara Channel (locally eastern portions) each afternoon and evening into early next week. Thus, there is a 40-60% chance for SCAs to be issued each day, with highest chances this weekend. Local SCA gusts will be possible each afternoon-evening across the Santa Monica Bay and San Pedro Channel into early next week.
The southerly swell that has impacted the coastal waters over the last few days will continue to gradually subside today.
09/133 AM.
There is a very low (but non-zero) chance of thunderstorms across the Los Angeles and Ventura Beaches today. Any thunderstorm that forms could produce local gusty and erratic winds, brief heavy downpours, and dangerous cloud-to- ground lightning.
Moderate to locally moderate coastal flooding will continue through Thursday around evening high tides for south facing shores. Even though the south swell from post tropical cyclone Marie is subsiding, the tides remain very high. The actual observed tides have been running about 6 inches above predictions, with the evening tides near or exceeding 7 feet.
While impacts will not be as extreme as the past few days, possible impacts include continued beach erosion, flooded sandy beach areas, bike paths, and parking lots, as well as low-lying roads. Some areas that may continue to see impacts are: the Alamitos Peninsula in Long Beach, Avalon on Catalina Island, and Oxnard to Malibu (including the Pacific Coast Highway near Point Mugu).
Beach Hazards Statements (BHS) have been issued for the beaches of Los Angeles and Ventura Counties due to the very high evening tides Wednesday and Thursday. There will be some lingering southerly swell today.
Ca, Extreme Heat Warning in effect from 8 AM this morning to 8 PM PDT Thursday for zones 38-87-88-340>358-362-366>375-548. (See LAXNPWLOX). Beach Hazards Statement in effect through Thursday evening for zones 87-349-350-354-362-366. (See LAXCFWLOX). Heat Advisory in effect until 8 AM PDT this morning for zones 362-366>373-548. (See LAXNPWLOX). PZ, Small Craft Advisory in effect until 3 AM PDT Thursday for zones 673-676. (See LAXMWWLOX).
