Submitted by ub on

The first tropical threat to the #USA this season isn’t on the East Coast or in the Gulf of Mexico. it is in Southern California.

‘It ain’t over till the fat lady sings as she brings heavy rain to SoCal. Tropical Storm Hilary, after barreling through Baja California, struck Southern California on Sunday, causing widespread, often heavy rain, flooding, downed trees, road closures, and power outages.

To add insult to injury, a 5.1 magnitude earthquake struck southern California as the state prepared for a rare and nearly unprecedented tropical storm. Hilary, the region’s first tropical storm in 84 years, dropped over half an average year’s worth of rain last night on some mountain and desert areas, including Palm Springs, bringing the city’s 911 system down. 

California Gov. Gavin Newsom urged residents to stay home as the National Weather Service issued a flash flood warning across much of LA County. The warning remains in effect until 3 a.m. local time, and the NWS said the rain could cause catastrophic flooding, mudslides, landslides, and debris flows. 

Updated hurricane information from NOAA NHC. Hurricane Hillary is now classified as a mega-hurricane with sustained winds at 120 knots (138 mph), gusts at 145 knots (166 mph), and forecast to continue to increase. Baja California is in for a potential big one. Also time for Nevada and even Oregon and Utah to be seriously looking at flood measures. As for the Atlantic, also time to get prepared though likely still a few days before this is confirmed. https://www.nhc.noaa.gov/gtwo.php?basin=atlc&fdays=7

Category 4 hurricane Hilary headed for California as SoCal sees first tropical storm watch


National Hurricane Center images change under a hurricane warning. The red, hurricane watch pink, tropical storm warning blue, and tropical storm watch yellow. The orange circle indicates the current position of the center of the tropical cyclone.

The black line, when selected, and the dots show the National Hurricane Center NHC forecast track of the center at the times indicated. The dot indicating the forecast center location will be black if the cyclone is forecast to be tropical and will be white with a black outline if the cyclone is forecast to be extratropical. If only an L is displayed, then the system is forecast to be a remnant low. The letter inside the dot indicates the NHC's forecast intensity for that time: 

D: Tropical Depression – wind speed less than 39 MPH
S: Tropical Storm – wind speed between 39 MPH and 73 MPH
H: Hurricane – wind speed between 74 MPH and 110 MPH
M: Major Hurricane – wind speed greater than 110 MPH

NHC tropical cyclone forecast tracks can be in error. This forecast uncertainty is conveyed by the track forecast "cone", the solid white and stippled white areas in the graphic. The solid white area depicts the track forecast uncertainty for days 1-3 of the forecast, while the stippled area depicts the uncertainty on days 4-5. Historical data indicate that the entire 5-day path of the center of the tropical cyclone will remain within the cone about 60-70 percent of the time. To form the cone, a set of imaginary circles are placed along the forecast track at the 12, 24, 36, 48, 72, 96, and 120 h positions, where the size of each circle is set so that it encloses 6 percent of the previous five years official forecast errors. The cone is then formed by smoothly connecting the area swept out by the set of circles.

It is also important to realize that a tropical cyclone is not a point. Their effects can span many hundreds of miles from the center. The area experiencing hurricane-force one-minute average wind speeds of at least 74 mph and tropical-storm-force one-minute average wind speeds of 39-73 mph winds can extend well beyond the white areas shown enclosing the most likely track area of the center. The distribution of hurricane and tropical storm force winds in this tropical cyclone can be seen in the Wind History graphic linked above.