textproduct: Los Angeles

SYNOPSIS

18/254 AM.

Night through morning marine layer clouds will be confined to the coastal areas, mostly north of Pt Conception, through much of this week. Warmer and drier conditions are expected away from the immediate coast, with peak heat likely being Tuesday through Thursday when moderate heat risk is expected in warmest locations.

LONG TERM (FRI-MON)

18/159 AM.

All medium range mdls agree that the upper high will shift to the four corners area by Friday, which will set up SE monsoon flow over Southern CA. This SE flow will allow precipitable Water values to approach 1.5" across southern L.A. County starting Friday afternoon. This influx of moisture will allow for a 5-10 percent chance of showers or thunderstorms to to develop over the LA County mountains and Antelope Valley Friday afternoon through the weekend. Hgts fall a to 592 dam and there will be an increase in mid and high level clouds as well. These two things will likely bring 1 to 3 degrees of cooling. Future shifts will have to weigh the opposing effects of the cooler temps vs the increased humidities and consider extending the heat advisories for one more day. Right now this appears to be about a 30 percent chc.

The upper high will shift slowly eastward Saturday through Monday and hgts will fall to about 590 dam. The onshore gradients do not change much so the pattern of plenty of morning low clouds over the Central Coast and minimal low clouds for areas south of Pt Conception should continue. 1 to 2 degrees of cooling each day should bring most max temps down to a few degrees under normal by Monday.

AVIATION

18/0955Z.

At 0822Z at KLAX, the marine layer was 600 feet deep. The top of the inversion was 2300 feet with a temperature of 28 C.

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

Fair confidence in TAFs for KSBP and KSMX. VFR conds could arrive +/- 1 hour from fcst time. There is a 25 percent chc of 1/4-1/2SM vsbys 11Z-15Z.

Moderate confidence in the remainder of TAFs with a 30 percent chc of IFR cigs at any given site 13Z-17Z.

KLAX...Moderate confidence in TAF. There is a 30 percent chance of BKN008 conds 13Z-17Z. No significant easterly wind component is expected.

KBUR...High confidence in CAVOK TAF.

MARINE

18/253 AM.

For the Outer Waters, high confidence in current forecast. Small Craft Advisory (SCA) level winds are expected through Saturday. Building short- period seas will also affect the Outer Waters, rising to the 6-9 foot range.

For the Inner Waters north of Point Sal, moderate confidence in current forecast. Through Wednesday, there is a 30-40% chance of SCA level winds in the afternoon and evening hours. For Thursday through Saturday, there is a 50-70% chance of SCA level winds in the afternoon and evening hours.

For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. For the western half of the Santa Barbara Channel, there is a 60% chance of SCA level winds late this afternoon and tonight. Then there is a 30-40% chance of SCA level winds during the afternoon to evening hours Wednesday through Saturday. Elsewhere south of Point Conception, high confidence in winds and seas remaining below SCA levels through Saturday.

LOX WATCHES/WARNINGS/ADVISORIES

CA...Heat Advisory in effect from 10 AM this morning to 8 PM PDT Thursday for zones 38-88-343>345-351-353-371>373-375-376-379-380-548. (See LAXNPWLOX). PZ...Small Craft Advisory in effect until 3 AM PDT Wednesday for zones 670-673-676. (See LAXMWWLOX).