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

12/1737Z.

At 1707Z at KLAX, there was no marine layer. There was a sfc based inversion with a top of the marine inversion was around 1700 feet with a temp of 24 deg C.

High confidence in VFR TAFs. 20% percent chance northeast winds 15-20 kt surface at KSBP during the period. Light LLWS possible through the period at KSBP, highest through this afternoon.

KLAX...High confidence VFR TAF. Moderate confidence in any east wind component remaining below 8 knots.

KBUR...High confidence VFR TAF.

MARINE

12/822 AM.

High confidence in northwest to north winds between 20-30 knots impacting the Outer Waters through at least Sunday night, with relative lulls possible today. There is a 50% chance of low end Gale Force winds (roughly 35 knots) across the waters beyond 30 NM from shore late Friday through Saturday morning. Seas will increase during this period, moderate confidence in seas reaching at least 10 feet across aforementioned areas. Conditions are likely to improve early next week, with relatively small seas expected.

Small Craft Advisory (SCA) level winds will approach the western edge of the Inner Waters along the Central Coast, but chances for these winds to reach nearshore areas are low.

Inside the Southern California Bight, conditions are expected to remain below SCA levels for the foreseeable future, except for hyper-localized SCA level winds across the far northwestern portion of the Santa Barbara Channel Saturday.

LOX WATCHES/WARNINGS/ADVISORIES

CA...Heat Advisory remains in effect until 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). Small Craft Advisory in effect from midnight tonight to 3 AM PDT Saturday for zone 676. (See LAXMWWLOX).