UPDATED, 7 p.m. with latest windspeed & graphics: In a rare occurrence, the remnants of Hurricane Hilary might hit Southern California and possibly Los Angeles this weekend with tropical storm-force winds (39-73 mph) and heavy rain.
What began as Tropical Storm Hilary off the coast of Mainland Mexico strengthened into a Category 2 hurricane early today. As of 5 p.m. PT, Hilary’s winds had strengthened to 120 mph, making it a major Cat 3 storm. On Friday, it’s expected to hit Cat 4, with an outside chance to hit Cat 5, before weakening. By Sunday, Hilary is expected to become a lesser hurricane and then potentially hit Southern California and Los Angeles with tropical storm-force winds, especially at higher elevations, later in the day. The storm was 475 miles south of Cabo San Lucas midday Thursday.
Here is the latest on the storm’s direction from the National Weather Service:
Hilary is moving toward the west-northwest near 14 mph (22 km/h), and this general motion is expected to continue through tonight. A turn toward the northwest is expected Friday morning, followed by a turn toward the north-northwest and north on Saturday. On the forecast track, the center of Hilary will approach the Baja California peninsula over the weekend.
Currently, per the NWS, “Hurricane-force winds extend outward up to 60 miles (95 km) from the center and tropical-storm-force winds extend outward up to 275 miles.”
Hurricane Hilary on Thursday morning (NOAA)
NOAA
The updated wind cone (featured as this story’s main image) has an increased chance of tropical storm-strength winds hitting the San Diego area, up from 30%-40% to 40%-50%.
There is also an outside chance of what’s known as a “wet” Santa Ana event, which could bring increased winds, as the circulation pushes north.
Here is the latest National Weather Service forecast chart:
Only one full-blown tropical storm has hit the coast of California in recorded history: the Long Beach tropical storm that made landfall near San Pedro in 1939, according to the NWS. No tropical cyclone has made landfall in California at hurricane intensity in recorded history.
Two factors tend to keep Southern California safe from such storms: colder sea surface temperatures, which take their fuel away, and upper-level steering winds in the eastern Pacific. This year’s El Niño event means ocean temperatures are much warmer than usual, with the water in Malibu registering 70 degrees today. Normally, 67 or 68 degrees is the warmest coastal ocean temperatures get in the summer in Los Angeles.
Still, hurricane tracks are tricky to predict, especially four days out. The most recent National Weather Service forecast for Hilary indicates: “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. However, having said that, virtually all the GEFS ensemble members show moderate to heavy rain amounts, especially south of Point Conception.”
That rainfall currently is pegged at a large accumulation for summer in Southern California with, per the NWS, “several solutions at or above 2.5″ and as high as 2.9” and “100 percent chance of rain” for much of Los Angeles. So the probability of a very anomalous rain event is certainly increasing. The official rain total forecast currently is around 1″-2″ area-wide Sunday through Tuesday but with the potential for much higher (or lower) amounts depending on the actual track. But that’s the low end. “Rainfall amounts of 2 to 4 inches, with isolated amounts in excess of 8 inches, will be possible across portions of southern California and southern Nevada,” per the latest NWS update.
August is generally L.A.’s driest month, with an average annual rainfall of 0″.
Just before 4 p.m., the NWS issued a flood watch for Los Angeles and Ventura Counties “from sunday afternoon through Monday evening.” According to the Weather Channel, flood watches have also been issued for much of San Diego, Orange, Imperial and Riverside Counties.
There could also be lightning which, if the storm hits some areas with wind but without rain, could create fire danger.
In terms of waves, the NWS indicates that Hilary “will bring the potential for hazardous marine conditions to all coastal waters starting this Sunday. While any wind/weather impacts from these systems over the local area are highly uncertain, long-period, steep, southerly swells and high surf will be possible during the upcoming weekend and beyond.”
Surf forecaster Surfline is predicting waves from 4-5 feet in Northern L.A. County and 6-8 feet in Northern Orange County, with Newport Jetties, a hurricane swell focal point, hitting 10-15 feet. Those estimates can drop radically in 24 hours, however, should the storm hew closer to the coast of Baja California or rise considerably if it were to move out further into Southern California’s swell window. Indeed, just Wednesday, Surfline was predicting 15-20′ surf in Northern L..A., which would be a rare occurrence for the region in summer.
Here is Thursday’s NWS Los Angeles forecast with a video update below:
Tropical storm Hilary is official now and expected to continue strengthening over the next couple days. The official track has it moving northwest, roughly parallel to the coast of Mexico, then west of the southern tip Baja Saturday morning. 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. However, having said that, virtually all the GEFS ensemble members show moderate to heavy rain amounts, especially south of Pt Conception. The EPS is not far behind that now as the last few solutions have trended more towards the more northerly GEFS. The mean PW from both ensemble systems is now right at 2″ with several solutions at or above 2.5″ and as high as 2.9″. So the probability of a very anomalous rain event is certainly increasing. The official rain total forecast currently is around 1-2″ area-wide Sunday through Tuesday but with the potential for much higher (or lower) amounts depending on the actual track. The potential exists for isolated flooding and residents, particularly near burn scars should monitor the situation closely. The most likely period for the heaviest rain is later Sunday into Monday, though again the speed and track of the storm will impact the timing and rain intensity.
With the current forecast track there is also the potential for gusty winds at times. Earlier models indicated as much as 8-9mb offshore LAX DAG gradient Sunday and Sunday night ahead of the storm’s arrival, though more recent runs have backed off that slightly. There is still the potential for a “wet” Santa Ana wind event Sunday with gusty northeast winds in the usual areas across L.A. and Ventura counties, but it will probably take a couple more days to have much confidence in that forecast.
Another potential impact will be the increase in south-to-southwest swells this weekend which could be high enough to create significant issues at south-facing harbors like Avalon and Long Beach, and even as far north as Morro Bay and Port San Luis along the Central Coast.
The storm is currently expected to exit the area by Tuesday, but lingering southeast flow aloft will keep at least a chance of showers going through the end of next week.
