12/221 AM.
Temperatures will increase each day into mid-week, resulting in widespread Moderate to Major HeatRisk Tuesday through Thursday. Monsoonal moisture moving into the area will add to the discomfort, additionally bring shower and thunderstorm potential each day, highest in the mountains.
(tdy-Tue), 12/337 AM.
Ample mid and high level clouds are streaming into the region from the south. Few (if any) observations sites have reported any rain, thus most moisture is not reaching the surface and will likely continue to fall mostly as virga through this morning. Light showers are possible though, especially for San Luis Obispo and Santa Barbara Counties. There remains around a 5% chance of dry lighting through this morning. Today through Tuesday there is a 10-20 percent chance of thunderstorms and showers over the LA, Ventura, and far interior Santa Barbara County mountains, while a 5-10 percent chance exists everywhere else. Storms are expected to produce more measurable rain starting today, and especially Monday and Tuesday. The influx of moisture will increase the humidity, making conditions muggier and increase any heat discomfort. The upper level clouds have disturbed the marine layer clouds, which are patchy and have been scattering and reforming overnight (the high clouds will also make for good sunset conditions).
Through Tuesday, 500 mb heights will experience minimal changes, but onshore flow will become much weaker. Some model guidance even show weak offshore flow during the mornings staring on Tuesday. This will dampen the cool seabreeze and allow for temperatures to rise more each the day. A warming trend is anticipated for the next several days, reaching widespread Moderate to Major HeatRisk on Tuesday. This will pose a threat of heat related illnesses to much of the population, not just those most vulnerable. All headlines (Advisories and Watches) remain in effect with no recent changes to the timings. Heat Advisories continuing into Tuesday morning, then the Extreme Heat Watches are in place Tuesday morning through Thursday evening.
Tuesday night, expect moderate Sundowner winds across southwest Santa Barbara County, and increasing northwest winds across interior areas.
(Wed-Sat), 12/319 AM.
Heat will be the primary hazard next week, and an Extreme Heat Watch is in effect Tuesday through Thursday for all areas except the beaches along the Central Coast. Widespread moderate to major HeatRisk is anticipated for the region. Over the next couple days, some locations are likely to to be converted to Heat Advisories, while others may become Extreme Heat Warnings. High temperatures in the warmest valleys and deserts have the potential to be between 95 to 110 degrees. Even the beaches and coastal plains may see highs between 85 and 95 degrees. Temperatures are favored to trend down Friday into the weekend, though there is a fairly large range of outcomes as to how much. The most likely scenario would bring temperatures back down to near normal for mid-July by the weekend. However, the humidity is poised to stay through the extended period (and beyond), and this would still present Minor to Moderate HeatRisk across much of the region, especially away from the coasts. Ensembles suggest PWATs hover around 1.5 inches during the period and even into the next week, so muggy days are in the near and long term future here is Southwest California.
The periphery of the high pressure centered over the Plains will nose into the Southern California region starting Wednesday. This will alter the flow pattern to be more southwesterly compared to the southeasterly flow expected earlier in the week. This will likely cut off the moisture source for the region, thus chances of thunderstorms and showers will likely drop to around 10 percent across the region for Wednesday and Thursday. However, starting Friday, other influx of monsoonal moisture from the southeast will be possible, and thunderstorm chances will likely bump back up to around 20 percent. The thunderstorm forecast will be complex with generally low confidence for any particular location, as storm development will be highly dependent on mesoscale features and even potential outflows form storms well outside of our forecast area. The greatest chances will be during the afternoon and evening hours across the mountains of Los Angeles and Ventura Counties.
Moderate Sundowner winds for southwestern Santa Barbara County and northwest winds over the interior are expected Wednesday night and potentially Thursday night (although weaker Thursday). Otherwise winds will trend slightly more onshore Thursday into the weekend.
12/1041z.
At 0655Z at KLAX, the marine layer depth was was 900 ft. The top of the inversion was at 4100 ft with a max temperature of 26 C.
High confidence in TAFs for KPMD, KWJF and KPRB.
Low to moderate confidence in the remaining TAFs. Mid and high clouds have disrupted the marine layer cloud formation, and any cigs that do form are likely to be patchy and scatter and reform frequently.
KLAX, Moderate confidence in TAF. There is a 40% chance of no MVFR cigs forming through this morning, and if any do form they may bounce between BKN012 and BKN250. High confidence that any east wind component will be below 6kt.
KBUR, Moderate to high confidence in TAF. There is a 20% chance of brief OVC008-015 cigs until 16Z Sun.
11/826 PM.
For the outer waters, winds and seas are largely expected to be below Small Craft Advisory (SCA) levels through Tuesday, then there is a 50%-60% chance of SCA winds and seas developing Tuesday night through Thursday night.
For the nearshore waters along the Central Coast, mainly light winds are expected through Tuesday, but winds will begin to increase on Tuesday, Likely reaching SCA levels Wednesday afternoon through Thursday night. Short period seas may also reach SCA levels.
For the inner waters south of Point Conception, conds are expected to remain below SCA levels through the forecast period, except for a 50% chance of SCA wind gusts over the western portions of the Santa Barbara Channel Wednesday and Wednesday night.
12/220 AM.
A south to southwest swell will continue to affect the coastal waters through next week. With this longer period swell, the potential for larger surf and a greater risk for rip currents will continue.
Evening high tides are expected to increase this weekend going into next week with Monday expected to be the highest tide of 7.1 to 7.7 ft above MLLW. There is the potential for some minor coastal flooding next week with the evening high tides and south swell. One thing that will need to be watched late next week into the weekend will be the potential of a greater south to southwest swell from potential tropical cyclone over the eastern Pacific.
Thunderstorms will be possible along the beaches today and going through next week (10-20% chance). For more information, please refer to the Beach Hazard Statement.
Ca, Heat Advisory remains in effect until 10 AM PDT Tuesday for zones 38-343>345-353-376>380. (See LAXNPWLOX). Extreme Heat Watch in effect from Tuesday morning through Thursday evening for zones 38-88-341>345-347>358-362-366>376-378>383-548. (See LAXNPWLOX). Heat Advisory remains in effect from 10 AM this morning to 10 AM PDT Tuesday for zones 88-368-372-373-375-548. (See LAXNPWLOX). Beach Hazards Statement in effect from 11 AM PDT this morning through Wednesday evening for zones 340-346-349-350-354-362-366. (See LAXCFWLOX). PZ, NONE.
