Hurricane Hilary Forecast: Tropical Storm-Force Wind, Rain & Big Waves to be Observed in LA

Hurricane Hilary Forecast: A former hurricane may, in a rare event, make landfall in Los Angeles this weekend with tropical storm-force winds (39–73 mph) and significant rainfall. The presentCaribbean Storm By Thursday at noon, storm Hilary off the coast of Mainland Mexico is expected to intensify into a major storm (Cat 3 or higher) by Saturday at midnight. By 1 p.m. Sunday, Hilary is anticipated to weaken into a hurricane before making landfall as a tropical storm in Southern California, possibly near Los Angeles.

The Long Beach tropical storm, which made landfall at San Pedro in 1939, is the only known instance of a full-blown tropical cyclone hitting the coast of California. No hurricane-force tropical cyclone has ever been observed making landfall in California.

These storms are typically avoided by Southern California due to two factors: upper-level steering winds in the eastern Pacific and colder sea surface temperatures, which deplete the storms’ fuel. The El Nio phenomenon this year has resulted in significantly greater ocean temperatures than usual; today, the sea in Malibu registered 70 degrees. The warmest coastal ocean temperatures Los Angeles typically experiences in the summer are 67 or 68 degrees.

Even still, four days in advance is a challenging time to anticipate a hurricane’s path. According to the most recent forecast from the National Weather Service, “There remains a very large spread in the ultimate track so this remains a very low confidence forecast in terms of the track as well as the impacts.” Having said that, almost all of the members of the GEFS ensemble predict moderate to heavy rainfall, especially in the area south of Pt. Conception.

Hurricane Hilary Forecast: Actual Reports

According to the NWS, there will likely be a significant accumulation of rain in Southern California this summer, with “several solutions at or above 2.5′′ and as high as 2.9.” So there is definitely a higher chance of a highly unusual rain event. Currently, a 1- to 2-inch area-wide total of rain is officially predicted for Sunday through Tuesday, but the actual track might result in significantly greater (or lower) totals.

There may also be lightning, which might increase the risk of a fire if it occurs with wind but no rain.

According to the NWS, Hilary will start to deliver potentially dangerous maritime conditions to all coastal waters on Sunday. Long-term, steep, southerly swells and high surf will be probable over the upcoming weekend and beyond, while any wind/weather impacts from these systems over the immediate area are highly unknown.

Waves of 4-5 feet are expected in Northern Los Angeles County and 6-8 feet in Northern Orange County, according to surf forecaster Surfline. However, should the storm hew closer to the Baja California coast or if it were to move out further into the swell window, those projections may drastically change within a day. In fact, on Wednesday, Surfline predicted 15-20′ surf in Northern Los Angeles, which would be unusual for the area in the summer.

Heatwave: why extreme weather forecasts have improved so much

Today’s NWS Los Angeles forecast:

Hilary is now a recognised tropical storm and is predicted to get stronger over the coming days. According to the official track, it will move in a northwesterly direction Saturday morning, nearly parallel to the Mexican shore. This forecast still has very little confidence in both the track and the impacts because the final track still has a very wide spread. Having said that, almost all of the members of the GEFS ensemble predict moderate to heavy rainfall, especially south of Pt Conception. Now that the last few solutions have tended more towards the more northerly GEFS, the EPS is not far behind that.

With multiple solutions at or above 2.5 inches and as high as 2.9 inches, the mean PW from both ensemble systems is now right at 2 inches. So there is definitely a higher chance of a highly unusual rain event. According to the official forecast, rain will fall from Sunday through Tuesday in an area-wide average of about 1-2 inches, but the actual trajectory of the storm could produce significantly higher (or lower) totals. There is a chance for isolated floods, therefore locals should keep a close eye on the situation, especially those who live close to burn scars. The date and intensity of the rain will depend on the storm’s speed and trajectory, but late Sunday into early Monday is when it will most likely rain heavily.

Hurricane Hilary Forecast: Prediction

There is a chance for occasionally gusty gusts given the current projected trajectory. Though more recent estimates have slightly backed off that prediction, earlier runs suggested as much as 8-9mb offshore LAX DAG gradient Sunday and Sunday night ahead to the storm’s approach. It will likely take a few more days before there is much confidence in the forecast for a “wet” Santa Ana wind storm with gusty northeast winds on Sunday in the typical locations spanning L.A. and Ventura counties.

Although the storm is now predicted to leave the region by Tuesday, persistent southeast flow aloft will maintain at least a probability of showers through the end of the following week.