textproduct: Los Angeles

SYNOPSIS

11/214 PM.

Temperatures will increase each day into mid-week, resulting in widespread Moderate to Major HeatRisk Tuesday-Thursday. Monsoonal moisture moving into the area will add to the discomfort, additionally bring shower and thunderstorm potential each day, highest in the mountains.

LONG TERM (WED-SAT)

11/211 PM.

The synoptic pattern is favored to bring more of a southwest upper level flow to the region Wednesday as the ridge marches more towards the middle of the United States, somewhat limiting shower and thunderstorm chances Wednesday and most likely Thursday to just the eastern LA County mountains. However, greater chances for slightly more widespread thunderstorm potential return Friday into the weekend as the ridge moves back towards the Four Corners, with southeast flow aloft favored in both the EC and GFS. The thunderstorm forecast this week is a complex and fairly low confidence one, as storm development will be highly dependent on mesoscale features and even potential outflows form storms well outside of our forecast area. With that being said, a 10-20% chance of thunderstorms exists each day next week, highest in the mountains in Ventura and LA Counties Friday through the weekend.

The other and potentially more impactful concern next week is the continual and increasing heat. Wednesday and Thursday are on track to be the warmest days in the forecast, with widespread moderate to major HeatRisk across the region, including at the coasts (focused south of Point Conception). Extreme Heat Watches are currently in effect for most of the region save for the immediate Central Coast. The most likely outcome is for some locations to be converted to Heat Advisories, while others will become Extreme Heat Warnings. While temperatures will trend down Friday into the weekend, 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 biggest concern wind-wise remains the potential for moderate Sundowner winds and northwest winds over the interior Wednesday night and potentially Thursday night, although weaker Thursday. Otherwise winds will trend slightly more onshore Thursday into the weekend.

AVIATION

12/0300Z.

At 0019Z at KLAX, the marine layer depth was was 1000 ft. The top of the inversion was at 4200 ft with a max temperature of 25 C.

High confidence in TAFs for KPMD, KWJF and KPRB.

Low to moderate confidence in the remaining TAFs. IFR conds expected from the Ventura sites and northward, with MVFR conds for the LA sites. The timing of low clouds and IFR/MVFR conds may be off +/- 2 hours. The arrival of mid to upper level clouds may disrupt the marine layer cloud formation, hence the reduced confidence for the coastal sites.

KLAX...Moderate confidence in the 00Z TAF. Arrival time of low clouds this evening could be off +/- 2 hours. Clearing of the low clouds on Sun morning could be off by the same amount. High confidence that any east wind component will be below 6kt.

KBUR...Moderate confidence in the 00Z TAF due to uncertainty in marine layer clouds and clearing times if cigs reach BUR tonight. There is a 40% chance of no CIGs.

MARINE

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.

BEACHES

11/150 PM.

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 starting Sunday and going through next week (10-20% chance). For more information, please refer to the Beach Hazard Statement.

LOX WATCHES/WARNINGS/ADVISORIES

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 Sunday to 10 AM PDT Tuesday for zones 88-368-372-373-375-548. (See LAXNPWLOX). Beach Hazards Statement in effect from Sunday morning through Wednesday evening for zones 340-346-349-350-354-362-366. (See LAXCFWLOX). PZ...NONE.