textproduct: Los Angeles

SYNOPSIS

09/310 AM.

Moderate heat impacts will continue through Friday away from the coast in response to a strong ridge of high pressure over the region. Temperatures will decrease slightly over the weekend as the ridge moves away from the region, but some heat impacts will continue. Monsoonal showers and thunderstorms will be possible starting Sunday. Temperatures will begin to build once again on Tuesday, potentially reaching Major Heat Risk levels, with the monsoonal moisture adding to the discomfort from the heat.

LONG TERM (SUN-WED)

09/310 AM.

The upper high will continue to drift to the NE and will end up over South Dakota by Monday where it will stay through most of next week. Srn CA will end up on the western periphery of the high and SE flow will set up and persist over the area. Hgts will not change much day to day and will be near 593 dam. At the sfc there will be gradual weakening of the onshore flow will the possibility of offshore flow developing from the north Tuesday or more likely Wednesday.

The SE flow will bring monsoon moisture into the area with partly to mostly cloudy skies due to mid and high level clouds likely Sunday and Monday. There will also be enough onshore flow to bring low clouds to the csts and lower vlys each morning. PWAT quickly increase overnight Saturday and persist into Monday. The moisture will be low enough to bring a 10-20 percent chc of showers and isold TSTMs to VTA and LA counties. The best chc each day will be in the afternoons and early evenings over the mtns esp the eastern LA mtns. The increase in humidities will keep the heat index high enough to continue the low end heat advisories for most areas away from the csts.

The monsoon will likely cut off on Tuesday and skies will be much clearer for Tue and Wed. The amount of marine layer clouds will shrink as the offshore trends take affect. The copious sunshine and weaker onshore flow will add up to two days of warming. The current forecast call for 3 to 6 degrees on Tue and 1 to 3 degrees on Wed. If, however, the offshore develops as some ensemble members indicate then max temps would end up much higher and an extreme heat watch is in effect to cover this possibility which stands at about 30 percent right now.

AVIATION

09/1014Z.

At 0825Z at KLAX, the marine layer was 900 ft deep. The top of the inversion was at 2300 ft deep with a temperature of 27 C.

High confidence in TAFs for KSBA, KBUR, KVNY, KPMD and KWJF.

Fair confidence in TAFs for KSBP and KSMX with a 30 percent chc of VLIFR conds 10Z-15Z. VFR conds could occur +/- 1 hour from fcst.

Good confidence in TAFs for KOXR and KCMA with a 15 percent chc of IFR cigs 13Z-16Z.

Moderate confidence in TAFs for KSMO, KLGB and KLAX. VFR transition could be off by +/- 90 minutes and cigs off by 300 ft.

KLAX...Moderate confidence in TAF. There is a 40 percent chc of no cigs. Good confidence that VFR conds will arrive between 1630Z and 1830Z. Good confidence that any east wind component will be AOB 6kt.

KBUR...High confidence in TAF.

MARINE

09/314 AM.

For the outer waters, current Gale Warnings look on track ending Thursday morning. Small Craft Advisory (SCA) level NW winds will follow, lasting through at least Friday morning. Large 10-12 ft seas will subside Friday, but current SCA may need to be extended into Friday night due to winds and seas.

SCA level NW-W winds, with local gusts near gale force are expected for the inner waters along the Central Coast until Thursday morning. There is a 40% chance of Gales across the nearshore waters along the Central Coast and the Santa Barbara Channel through Thursday morning. Local SCA level wind gusts are also possible for far western portions of the Santa Barbara Channel through Thursday morning.

For the inner waters south of Point Conception, conditions are expected to remain below SCA levels.

LOX WATCHES/WARNINGS/ADVISORIES

CA...Heat Advisory now in effect until 10 AM PDT Tuesday for zones 38-88-343>345-353-368-372-373-375>380-548. (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). Wind Advisory in effect until 8 AM PDT this morning for zones 349-351. (See LAXNPWLOX). PZ...Small Craft Advisory in effect until 5 AM PDT Friday for zones 645-670-673-676. (See LAXMWWLOX).