In its latest warning, the National Hurricane Center said Guilma had become a tropical storm in the north Pacific Ocean on Monday evening central Mexico time.
The tropical storm had sustained wind speeds of 60 mph.
All times on the map are in Mexico Central Time. From The New York Times
Girma is the seventh named storm to form in the eastern Pacific Ocean in 2024.
What does a storm look like from above?
Satellite imagery helps determine the strength, size, and organization of a storm. The stronger the storm, the more likely it is to form an eye in the center. If the eye appears symmetrical, it often means the storm isn’t encountering anything that could weaken it.
Where will it rain?
Flash flooding can also occur inland, away from the storm’s center. Even weak storms can produce enough rainfall to flood low-lying areas.
Storms that form in the Atlantic or Pacific Oceans generally move westward, making Atlantic storms a bigger threat to North America. If a storm forms close to land in the Pacific Ocean, it can bring damaging winds and rain before being pushed out to sea.
But air masses can block storms and send them north or northeast toward the Baja California Peninsula or the west coast of Mexico. Sometimes, like Hurricane Hillary last year, the storms can move farther north, bringing destructive winds and torrential rain to Southern California.
The eastern Pacific hurricane season began on May 15, two weeks before the Atlantic season began. Both seasons last until November 30.
Another factor for storm watchers this year is the high likelihood of a La Niña event, an intermittent, large-scale atmospheric pattern that can affect weather around the world.
In the Pacific Ocean, La Niña increases wind shear, which is the change in wind speed and direction with height. This change makes storms less likely to form. (In the Atlantic Ocean, La Niña has the opposite effect, decreasing wind shear and making storms more likely.)
Sources and Notes
Tracking Map Tracking data is provided by the National Hurricane Center. The map shows at least a 5 percent probability. Forecasts are up to 5 days out, up to 3 hours before the storm is reported to reach its latest location. Wind speed probability data is not available north of 60.25 degrees north latitude.
Wind Arrival Table Arrival times are generated by New York Times analysis of National Hurricane Center data. Geographic locations are from the U.S. Census Bureau and Natural Earth data. Time zones are from Google. Table shows projected arrival times for specific cities that may be reached by sustained damaging winds of 58 mph or greater. If damaging winds reach a specific location, there is less than a 10 percent chance that they will arrive before the “earliest reasonable” time and a 50 percent chance that they will arrive before the “most likely” time.
Radar Maps Radar imagery is provided by the National Oceanic and Atmospheric Administration through Iowa State University. These mosaics are produced by combining the individual radar stations that make up the NEXRAD network.
Storm Surge Map Storm surge data is provided by the National Hurricane Center. Forecasts only cover the U.S. Gulf Coast, Atlantic Coast, Puerto Rico, and the U.S. Virgin Islands. Actual areas that may be flooded may differ from those shown on this map. This map takes into account tides, but does not account for flooding caused by waves or rainfall. This map also includes intertidal areas that are regularly flooded during normal high tides.
Satellite map imagery provided by the National Oceanic and Atmospheric Administration.
Precipitation Maps Multi-day forecast or observed precipitation totals data is provided by the National Weather Service. Single-day forecasts are provided by the National Oceanic and Atmospheric Administration.