textproduct: Los Angeles

SYNOPSIS

04/949 PM.

Mostly clear skies, dry conditions, a general warming trend with periods of offshore winds are likely through the week. The warmest and windiest conditions are likely on Friday and Sunday.

LONG TERM (MON-THU)

05/1242 PM.

For the extended, rather benign weather should continue. Synoptically, the ridge will remain over the area through Wednesday (although a little bit weaker) then will be shifted eastward on Thursday as a trough approaches the West Coast. At the surface, this will be reflected with decreasing offshore flow through Tuesday then weak diurnal flow Wednesday and Thursday.

Forecast-wise, Monday through Wednesday will be rather unremarkable. With the weakening offshore flow and weakening upper ridge, there will be a slight cooling trend through this period although temperatures will generally remain 3-6 degrees above normal. Skies should remain mostly clear as lingering offshore flow will prevent any stratus development.

On Thursday, things will begin to change. With the approaching upper level trough, there will be a return of onshore flow and cooler temperatures for all areas. Based on current guidance, there will be a chance of some light rain developing during the day on Thursday.

Further out Friday through next weekend, deterministic and ensembles indicate some wet and unsettled weather, but differ dramatically in the details (timing, amounts, etc.). Ensembles from both the GFS and ECMWF indicate decent chances of widespread 1+ inch totals. Hopefully, models will come into some sort of focus as we draw nearer to next weekend.

AVIATION

06/0248Z.

At 0154Z at KLAX, there was an inversion at 1300 ft. The top of the inversion was 2000 feet with a temperature of 19 degrees Celsius.

For 00Z TAF package, high confidence in CAVU conditions for all sites.

KLAX...High confidence in 00Z TAF as CAVU conditions are expected through the period. No significant easterly wind component is expected.

KBUR...High confidence in 00Z TAF as CAVU conditions are expected through the period.

MARINE

05/740 PM.

For the Outer Waters, moderate to high confidence in current forecast. Through Saturday, high confidence in a combination of Small Craft Advisory (SCA) level winds and seas prevailing across all of the Outer Waters. For Sunday through Tuesday, there is a 50-70% chance of the combination of SCA level winds and seas continuing.

For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. Tonight through Saturday, moderate confidence in winds and seas remaining below SCA levels, with a 30% chance for SCA level seas tomorrow through Saturday. For Sunday and Monday, there is a 50% chance of SCA level seas, but high confidence in winds remaining below SCA levels. For Tuesday, high confidence in winds and seas remaining below SCA levels.

For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. Through late tonight, high confidence in winds and seas remaining below SCA levels. For Friday, there is a 40% chance of SCA level northeast winds from Point Mugu to Santa Monica. On Saturday, there is a 60-70% chance of SCA level northeast winds from Point Mugu to Santa Monica. For Sunday through Tuesday, high confidence in winds and seas remaining below SCA levels.

BEACHES

05/740 PM.

High tides will build each morning and peak Sunday and Monday at 7.2 to 7.6 feet (MLLW). Meanwhile, a west to northwest swell will slowly build into the area, peaking on the Central Coast Friday and Monday, and peaking everywhere else around Monday. This combination of high tides and high surf will bring hazardous swimming conditions, dangerous conditions on rock jetties, and a risk for moderate coastal flooding. If you are in the coastal areas, listen to advice from your local officials.

With the daily high tides changing only a little Friday through Tuesday, the risk for coastal flooding will peak when the surf peaks (Friday and Monday for the Central Coast, and Monday for the rest of the coastal areas). This coastal flooding event will differ in several ways from the past episodes this year. First, while tides will be high, they will not be nearly as high as the record breaking tides from last week. This means that the impacts to harbor areas and Naples Island will generally be minor compared to last week. Shallow flooding should be expected, especially for low-lying walkways, but of a lesser degree less in severity and coverage. Second, for the beach-side coastal areas, the swell is from the west to northwest and not from the south, which characterized the coastal flooding episodes of September and early October. This means that areas hit hard in those events, like Long Beach and Malibu, are less at risk with this upcoming event. For west-facing shores however, the risk is much higher than events in the recent past. Areas like Oceano and Cayucos on the Central Coast, and Ventura on the southern coasts, have elevated risks of moderate coastal flooding. Moderate coastal flooding impacts include things like flooded sandy beach areas, moderate beach erosion, as well as shallow flooding of beach parking lots and bike paths. Isolated damage is unlikely but cannot be ruled out especially considering the extent of beach erosion we have already seen - which limits the natural protective buffer between the ocean and coastal infrastructure.

For the Central Coast, a High Surf Advisory and Coastal Flood Advisory will be in effect for Friday through Monday, since there will be an earlier peak to the surf. For all other coasts, a Beach Hazards Statement will be in effect for Friday through Tuesday, with a key note that some areas (especially Ventura County) may need to be upgraded around Monday when the surf peaks.

FIRE WEATHER

05/130 PM.

Weak to moderate Santa Ana winds will be on the increase, peaking on Saturday. During the peak, gusts of 30 to 45 mph will be common in the typical wind-prone areas of Los Angeles and Ventura Counties from the mountains to the coast. Local gusts of 45 to 55 mph are possible in the windiest locations like the San Gabriels, Santa Susanas, and western Santa Monicas. Meanwhile, the air will warm and dry, with minimum humidities in the 8 to 20 percent range common by Saturday. While some sprouting green grasses and wet soils from recent rains are limiting factors to the fire risk, there is still large swaths of the area where the grasses are dead. The brush remains dormant, with live fuel moistures still at critical levels. With all that in mind, there is a high risk for fast-moving fires where the plants are driest and the winds are strongest. This includes the western San Gabriel Mountains, Santa Susana Mountains, Santa Monica Mountains, and the Santa Clarita Valley. These areas will be under a targeted Red Flag Warning for Saturday. The rest of the area still has an elevated fire risk, but not to an extreme-level that warrants a Red Flag Warning.

Residents in high fire risk areas should be prepared in case a fire starts. Review your evacuation plans...what would you bring, where would you go. Stay extra aware of your surroundings. Make sure your vehicle is fueled up. For everyone, do your part by avoiding anything that could spark a fire.

LOX WATCHES/WARNINGS/ADVISORIES

CA...Wind Advisory in effect until 11 PM PST this evening for zones 349>352. (See LAXNPWLOX). Red Flag Warning in effect from 2 AM to 6 PM PST Saturday for zones 288-369-370-375-379. (See LAXRFWLOX). PZ...NONE.