textproduct: Los Angeles

SYNOPSIS

11/209 AM.

A significant and long lasting heat wave is expected to affect the region starting Thursday and extend well into next week with MODERATE to HIGH heat impacts likely.

LONG TERM (SUN-WED)

12/258 AM.

The ridge will begin to reform on Sunday, but the day will also start off with a decent sized marine layer cloud deck across the csts and lower vlys. Offshore trends in the afternoon will ensure good clearing and when combined with slightly higher hgts will bring 1 to 3 degrees of warming.

Another heat wave will take aim at Srn CA starting Monday and lasting through at least Wednesday. The east PAC high will push into and over srn CA and is forecast to bring fairly extraordinary 500mb hgts between 590 and 593 dams. Looking at records dating back to 1948 the highest previously recorded 500 mb hgt for March is 591 dam. Look for 3 to 4 locally 5 and 6 degrees of warming each day Mon and Tue with only a small retreat in temps on Wed. Tuesday's highs will be reaching towards 100 degree in the vlys and even 100 may be too low in the warmest vly locations. Another round of widespread Heat Advisories are a near certainty. Both daily and monthly records could fall esp on Tue. As mentioned in the earlier discussion: the Antelope Valley could break a record for the earliest 90 degree day in the calendar year.

A little more cooling is forecast Thursday but max temps will remain 15 to 22 degrees over normal.

Given the unprecedented length and magnitude of this extreme heat wave, heat stress will be a real threat each day, especially in areas that aren't used to the heat, like the coastal areas, where people may not have methods to cool off their homes. Try to complete outdoor activities early in the day or in the evening, and don't leave people or pets in cars.

Dry weather looks to continue for a while yet. Both the EC-AI and the GFS-AI do not show any rain all the way through the 26th.

AVIATION

12/1122Z.

At 0842Z at KLAX, there was no marine layer. There was a sfc based inversion with a top of the marine inversion was around 1600 feet with a temp of 24 deg C.

High confidence in CAVU TAFs.

KLAX...High confidence CAVU TAF. Any easterly winds should remain less than 7 knots.

KBUR...High confidence CAVU TAF.

MARINE

12/149 AM.

Moderate to high confidence in the current forecast.

For the outer waters, there is a 60% chance of borderline Small Craft Advisory level wind gusts will affect the waters through at least Friday night, although the northern waters (north of Point Sal) may drop below SCA levels during the morning and afternoon hours on Friday. Friday night through Sunday night, there is a 50-60% chance of SCA wind gusts, with the highest chances across the northern waters where local Gale Force gusts will be possible. Seas will be near SCA levels Friday night through Saturday night. Monday and Monday night, there is a good chance conds will drop below SCA levels for all the outer waters.

For the inner water N of Point Sal, conds are expected to be generally below SCA levels through Monday night, except for a 50% chance of SCA wind gusts at times during the afternoon and evening hours Friday and Saturday.

For the inner waters S of Point Conception, conds are expected to remain below SCA levels through Monday night.

LOX WATCHES/WARNINGS/ADVISORIES

CA...Heat Advisory remains in effect from 10 AM this morning to 8 PM PDT Friday for zones 88-340>342-346>352-354>358-362-366>375-548. (See LAXNPWLOX). PZ...Small Craft Advisory in effect until 3 AM PDT Saturday for zones 670-673. (See LAXMWWLOX).