textproduct: Los Angeles

SYNOPSIS

18/620 PM.

Well below normal temperatures to continue through the weekend, with a deep marine layer and a few spits of drizzle, as well as gusty winds over the interior. A significant warming trend will start Monday or Tuesday and peak Wednesday and Thursday.

LONG TERM (MON-THU)

18/212 PM.

Zonal flow will continue over the area through at least Monday morning before anticyclonic flow develops as an upper level high strengthens ESE of SoCal. The onshore flow will weaken just a little bit. This should decrease the morning cloud coverage a little bit and allow for somewhat better and faster clearing. Look for around 3 to 6 degrees of warming is possible Monday as hgts rise a little and compresses the marine layer.

Models have backed off a little on the degree of warming slated for next Tue-Thu. Hgts should still warm to an above normal with global ensembles supporting 593-596 dam, which will be around the 90th-95th percentile of climatology. At the sfc, mdt-stg onshore flow will persist in the W to E direction, but the onshore push to the north will weaken through the period. The higher hgts will likely smoosh the marine layer to 1000 ft or less which will greatly reduce the amount of clouds making it into the vlys in the mornings. This compression will strengthen the marine inversion which will hinder the clearing near the shore. The current forecast calls for 2 to 4 degrees of warming each day Tue and Wed with little change on Thursday. This warming would bring vly temps into the mid 80s and lower 90s. Latest NBM has good chances (50%) of reaching 100 degrees across the Antelope Valley and even slight chances (10%) in Paso Robles Wed-Fri. An Extreme Heat Watch was issued for Tue-Thu for parts of LA County, including LA, with temperatures expected to reach the 80s, to around 90 east of Downtown LA. With an influx of people, especially those not from the area, and events the risk of heat impacts will be greater, despite forecast HeatRisk magnitudes of high-end Minor to low-end Moderate.

AVIATION

19/0106Z.

At 00Z at KLAX, the marine layer was 2500 ft deep. The top of the inversion was near 5000 ft with a temperature of 20 Celsius.

High confidence in KPMD & KWJF staying VFR with gusty southwest winds.

Moderate confidence in ceilings at all other airports. High confidence in flight categories (MVFR-VFR). Low confidence in timing (+/- 5 hours).

KLAX...High confidence in MVFR ceilings forming tonight. Low confidence in timing (+/- 5 hours). No significant east wind component expected.

KBUR...Moderate confidence in MVFR ceilings forming tonight with slightly stronger than usual onshore winds in the afternoon and evening hours.

MARINE

18/627 PM.

Fairly high confidence in winds and seas staying below Small Craft Advisory (SCA) criteria through Sunday, but typically gusty winds of 15 to 20 knots will form each afternoon and evening over many nearshore waters as well as around the Channel Islands.

BEACHES

18/241 PM.

A long period south to southwest swell (14 seconds and 16 seconds) will continue to affect the coastal waters through at least Friday. A Beach Hazard Statement is in effect through Thursday evening due to elevated surf of 3 to 5 feet on south- facing beaches of Ventura County Beaches, Malibu Coast, and Los Angeles County Beaches. Portions of the Southern Santa Barbara County Beaches could see surf to 2 to 4 feet.

High tides will continue to lower and should stay below 6.5 feet MLLW. The coastal flooding risk has lowered significantly as a result.

LOX WATCHES/WARNINGS/ADVISORIES

CA...Extreme Heat Watch in effect from Tuesday morning through Thursday evening for zones 88-368-372-373-379-380-548. (See LAXNPWLOX). Beach Hazards Statement in effect until 3 AM PDT Friday for zones 349-350-354-362-366. (See LAXCFWLOX). Wind Advisory in effect from 1 PM to 10 PM PDT Friday for zones 381-383. (See LAXNPWLOX). PZ...NONE.