textproduct: Los Angeles

SYNOPSIS

26/154 AM.

High temperatures will remain above normal through today with areas of low clouds and fog this morning. Substantial cooling is expected Sunday and Monday. Beach impacts from Tropical Cyclones well south of the region will be possible Monday and Tuesday in the form of high surf and possible beach erosion. A significant warming trend is expected Tuesday and Wednesday.

LONG TERM (TUE-FRI)

26/310 AM.

Still a lot of uncertainty in the weather forecast Tuesday and beyond. More than 50 percent of the models are indicating high pressure building over the state behind the exitting trough, with offshore flow and a fairly substantial warming trend through at least Thursday. There's at least a 30 to 40 percent chance of near 100 degree temperatures in the valleys and similar chances for Downtown LA and San Luis Obispo reaching 90 or higher. There's also a lower but still significant chance of temperatures 5-10 degrees cooler than that. Will have to wait to see how the hurricanes track before having much confidence in the longer range.

AVIATION

26/1700Z.

At 1604Z at KLAX, the marine layer was 900 ft deep. The top of the inversion was at 2700 feet with a temperature of 25 Celsius.

High confidence in VFR TAFs for KPRB, KBUR, KVNY, KWJF, and KPMD.

Low confidence in flight cats tonight for remaining TAFs. Chance for no low clouds tonight at KSBP (50%) and KSMX (30%). There is a 20-40% chance for IFR-MVFR cigs tonight at remaining sites, highest for KLAX/KLGB/KSMO. South of Point Conception cigs would likely be patchy and may frequently bounce between SCT and BKN if they form.

KLAX...High confidence in TAF through 06Z, then low confidence in flight cat thereafter. 40% chance for BKN007-012 conds 10Z-17Z. If cigs form they may bounce between BKN and SCT frequently.

Moderate to high confidence in TAF through 18Z Sat and after 03Z Sun, otherwise high confidence. CIGs may scatter and reform several times due to high level clouds this morning. There is a 30% chance of BKN008-012 CIGs after 03Z Sun. High confidence in no significant east win component.

KBUR...High confidence in VFR TAF.

MARINE

26/840 AM.

Through this weekend, moderate to high confidence in Small Craft Advisory (SCA) winds and steep seas affecting the outer waters. The current SCAs will likely be extended through Tuesday night. Gale force gusts will be possible at times, especially Monday afternoon and evening across the southern waters. Nearshore along the Central coast will see SCA winds and steep seas this afternoon into evening.

Moderate to high confidence in widespread gusty winds Monday into Tuesday extending into the nearshore waters at times, with the highest confidence in the Central Coast waters and Santa Barbara Channel.

Southerly swells from Hurricanes Odalys (SSW) and Polo (SSE) will affect the region this weekend through the middle of next week. These swells will create larger waves and surf nearshore, which could impact some harbor entrances, especially Sunday through Tuesday.

BEACHES

26/858 AM.

Southerly swells from Hurricanes Odalys and Polo will affect the waters this weekend through the middle of next week. This is a complex scenario with two hurricanes so close in proximity, with one of them (Odalys) poorly handled by our computer models. Another complexity is the relatively short window of time that Polo is far enough west for its waves to have a clear path to southern California. This means that the swells will have a narrow window of time to line up with the high tides. Lastly, some south-facing shores are extra vulnerable because of the lingering erosion effects from Hurricane Marie earlier this month.

While the surf heights will likely be in the 4 to 7 foot range for south facing beaches Sunday through Tuesday, there is a plus or minus in that potential of 2 feet or so due to the complications mentioned above. High tides will steadily build each day and peak Monday and Tuesday, likely reaching around 7 feet (MLLW) - which is higher by almost a foot over astronomical tides due to ongoing effects of El Nino.

There is a significant concern of Coastal Flooding over vulnerable south-facing beaches as a result, but the magnitude is still uncertain. The areas of most concern include Avalon, Long Beach, Malibu and Santa Barbara. The reasonable worst-case scenario is for impacts similar to those from Hurricane Marie, but the most likely outcome is for impacts to be a step less. The one exception being Avalon on Catalina Island, as the swells from Hurricane Polo will be more from a southeasterly direction than with Marie, which they are more exposed to. The same goes for Santa Barbara Harbor where the risk is less but still present.

South-facing beaches should plan for shallow flooding of seawater over low lying beach walkways, parking lots, and roads as well as potential for significant beach erosion. Very localized damage to structures is also possible in the most vulnerable areas. With all that stated, there is a potential that impacts will be minimal if the lower-end surf outcome materializes.

Due to rather high uncertainty, the Beach Hazard Statements will continue through Wednesday afternoon. This covers the coastline from Santa Barbara South coast down to LA county, including Catalina island. A decision to upgrade to Coastal Flood Advisory will be made today or Sunday.

LOX WATCHES/WARNINGS/ADVISORIES

CA...Beach Hazards Statement in effect through Wednesday afternoon for zones 87-349-350-354-362-366. (See LAXCFWLOX). PZ...Small Craft Advisory in effect from 3 PM this afternoon to 9 PM PDT this evening for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Monday for zones 670-673-676. (See LAXMWWLOX).