textproduct: Los Angeles

SYNOPSIS

05/230 AM.

A major and long lasting heat wave will to persist through at least Thursday with dangerously high temperatures. Friday into Sunday, temperatures will trend cooler each day and there is a small chance of showers and thunderstorms due to moisture from distant Hurricane Rachel.

LONG TERM (THU-SUN)

05/229 AM.

Some coastal cooling is forecast for Thursday esp across the Central Coast. This cooling is dependent on the gradient forecast being correct and there is a 30 percent chc that the cooling will not be as much as forecast. Whatever the cooling it will not be enough to end the heat threat and all heat warnings and advisories will continue into the evening.

There is good consensus that on Friday the upper high will be replaced by weak cyclonic flow and hgts will fall to 583 dam. Most importantly there will be onshore flow to the east and only weak offshore flow from the north. Highs will still be above normal with 80s and lower 90s across the csts and 90s in the vlys. A few areas in LA county may still need heat advisories, but overall it will be a warm but not dangerously hot day.

Actual troffing moves into the state on Saturday. Onshore flow will increase as well. Marine layer stratus will likely begin to form across some of the coasts. Max temps will drop 4 to 8 degrees across the board. Even with this cooling most max temps will end up 3 to 6 degrees over normal.

The moisture from Hurricane Rachel will begin to move into the area on Sunday. It will produce a 20-30 percent chc of showers mostly over LA county and points south. Continued troffing and onshore flow will bring a more robust marine layer cloud pattern and an additional 4 to 8 degrees of cooling. This cooling will bring a return of blo normal max temps.

Swell from Hurricane Rachel will likely arrive Tuesday.

AVIATION

05/1837Z.

At 1820Z at KLAX, there was no marine layer or inversion.

Moderate confidence in TAFs for KSMX with a 40 percent chc no clouds devloping tonight, at KSBP there is a 15 percent chc of VLIFR conds for a few hours tonight into tomorrow morning.

High confidence in the remainder of the CAVU TAFs.

KLAX...High confidence in CAVU TAF. East wind of 5-7 kts are expected until 19-20Z and then will switch to westerly.

KBUR...High confidence in CAVU TAF.

MARINE

05/207 AM.

Generally quiet conditions are expected across the coastal waters through the forecast period. Localized Small Craft Advisory (SCA) gusts may occur each afternoon and evening between Point Conception and San Nicolas Island, off the coast of Point Dume, and across the San Pedro Channel. Winds over the outer waters will begin to increase Wednesday night through Friday with a 30% chance of SCA gusts at times, mainly during the afternoon to evening hours.

Night through morning dense fog may affect portions of the coastal waters west of the Channel islands and Point Conception through Thursday.

LOX WATCHES/WARNINGS/ADVISORIES

CA...Extreme Heat Warning in effect until 8 PM PDT Thursday for zones 38-87-88-349>358-362-366>375-548-550. (See LAXNPWLOX). Beach Hazards Statement in effect from Tuesday afternoon through Friday evening for zones 87-354-362-366. (See LAXCFWLOX). Heat Advisory in effect from 10 AM Wednesday to 8 PM PDT Thursday for zones 340-346. (See LAXNPWLOX). Heat Advisory in effect until 8 PM PDT Thursday for zones 341>345-347-348. (See LAXNPWLOX). PZ...NONE.