textproduct: Los Angeles

SYNOPSIS

18/757 PM.

Temperatures are expected to change little over the next few days, and most areas will remain near normal. Morning low clouds and fog will return to many coastal areas each night through morning into early next week. A warming trend is expected by the middle of the week, as upper level high pressure builds into the area while onshore gradients weaken.

LONG TERM (WED-SAT)

18/146 PM.

The large western U.S upper level high pressure center is forecast to drift to the area around New Mexico and the northern Texas Panhandle by Thursday. Southwestern CA will continue to be on the western periphery of this large upper level high, with 500 mb heights slowly increasing to 592-594 dam during the extended period.

As a result, the flow aloft will mostly be from the SE, bringing monsoon moisture into the region through much of the week. Precipitable water (PWAT) values are forecast to be 1.25 to 1.50 inches through much of the week for areas south of Point Conception and through mid-week for north of Point Conception. These PWATs are about 150 percent of normal for this time of year. Although the deepest moisture and is forecast to remain east of L.A. County during the extended period, it does look like the best chance of afternoon convection will come Wednesday and Thursday over the mountains of at least Ventura and L.A. Counties. However, right now chances remain around 10% for thunderstorms across the mountains, and are too low to include in the official forecast at this time. As we draw closer to early next week, we should have a better idea of the chance and extent of afternoon convection for the middle of next week.

Otherwise, it looks like varying amounts of night and morning coastal low clouds and fog will prevail during the extended period, with a warming trend through the middle of next week. Moderate to high heat risk may expand into Wednesday or Thursday as pressure gradients weaken and maybe turn lightly offshore in the mornings with the potential for 500 mb heights building to 594-596 dam. There is a moderate chance (at least 60 percent chance) that at least Heat Advisories will be needed in some areas, including potentially near the coast, by Wednesday. Also of note, Sundowner winds in southern Santa Barbara Counties could reach near advisory thresholds into Wednesday and Thursday.

AVIATION

19/0429Z.

At 0349Z at KLAX, the marine layer was 900 ft deep. The top of the inversion was at 2400 ft with a max temperature of 25 C.

High confidence in VFR TAFs for KPMD, KWJF, KBUR, KVNY, & KPRB.

Low to moderate confidence in remaining TAFs. CIG arrival and clearing times may be off +/- 3 hours and CIG heights off by +/- 300 ft.

There is a 50% chance that IFR CIGs do not arrive at KSBA and 40% chance for KCMA.

KLAX...Moderate confidence in TAF. Arrival and clearing times of MVFR CIGs 012-015 may be off +/- 3 hours of current forecast. 30% chance CIGs arrive as IFR 008-010 for a couple hours before lifting to MVFR. There is a 15% chance CIGs do not arrive or remain intermittent. No significant east wind component expected.

KBUR...Moderate confidence in TAF. 10% chance for IFR conds between 12Z and 16Z. No wind issues expected.

MARINE

18/757 PM.

Conditions rose to Small Craft Advisory (SCA) levels late this afternoon with gusts of 25 to 30 knots across the outer waters and an Advisory was issued through late tonight. Otherwise, conds are expected to remain below SCA levels through Monday except for localized SCA level northwest wind gusts across the Outer Waters more than 20 NM from shore (except for near Point Conception). Northwest winds will begin to strengthen Tuesday, rising to SCA levels by Wednesday and likely to last through late in the week.

A series of moderate period southerly swells will move through the waters late Sunday through much of next week which may impact south facing harbors, including the Port San Luis area.

BEACHES

18/757 PM.

Over the eastern Pacific, Tropical Storm Elida is forecast to move to the west-northwest well off the Baja Coast and eventually the California coast. Another tropical disturbance is expected to develop in the same area and follow a slightly more westerly track along 20 N Latitude. Both systems will produce moderate period southerly swells. High Surf Advisories and Beach Hazards Statements have been issued across Southwest California from Sunday evening through Tuesday night.

The secondary system on the heels of Elida and an incoming long period southern hemisphere south swell arriving later next week will contribute to continued and potentially more hazardous beach conditions into the following weekend. Additional High Surf Advisories and/or Beach Hazards Statements are likely next week.

LOX WATCHES/WARNINGS/ADVISORIES

CA...High Surf Advisory in effect from 5 PM Sunday to 11 PM PDT Tuesday for zones 87-354-362-366. (See LAXCFWLOX). Beach Hazards Statement in effect from Sunday afternoon through Tuesday evening for zones 340-346. (See LAXCFWLOX). PZ...Small Craft Advisory in effect until 3 AM PDT Sunday for zones 670-673-676. (See LAXMWWLOX).