On Thursday, Hurricane Hilary displayed rapid intensification in the Pacific Ocean, positioned southwest of Mexico. It is projected to bring substantial rainfall and potential flooding to portions of the Southwest as it weakens into a lesser system over the upcoming weekend.
During Thursday evening, Hilary underwent significant strengthening, attaining the status of a major Category 3 hurricane. The National Hurricane Center reported sustained winds of 120 mph, accompanied by even more forceful gusts.
As it progresses, the storm is anticipated to elevate to Category 4 hurricane strength by Friday, with winds reaching a minimum of 130 mph, as cautioned by the center.
As of Thursday evening, the hurricane was situated approximately 445 miles to the south of Cabo San Lucas, Mexico.
As the storm progresses northward over the next few days along Mexico’s Baja Peninsula, the potential for the heaviest rainfall and strongest winds in the US encompasses a broad spectrum of possibilities.
Minor variations in the hurricane’s trajectory hold the capacity to alter the projected scenarios for the most intense precipitation and wind strength.
The influx of Hilary’s rainfall might make its appearance as soon as Saturday in certain sections of the Southwest, with the peak impact anticipated to reach California in the early hours of Monday.
Modifications to the predicted path will also determine which regions of northwestern Mexico will bear the brunt of Hilary’s forceful winds.
These winds possess the capability to uproot trees, disrupt power lines, and inflict significant damage on properties situated closest to the storm’s core.
From Thursday through early Monday, the Baja Peninsula in Mexico may face extensive mudslides and swift flooding as an anticipated rainfall accumulation of around 3 to 6 inches is predicted.
Higher elevated regions could potentially experience even greater amounts of precipitation during this period.
Significant flood potential
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A notable potential for flooding exists as Hurricane Hilary is poised to undergo significant weakening before reaching Southern California and portions of the Southwest. These regions face an escalating likelihood of considerable impacts in the form of intense rainfall and subsequent flooding.
Southern California is expected to bear the brunt of Hilary’s substantial rainfall. Over the span of Saturday through Monday, widespread precipitation levels ranging from 2 to 4 inches are projected for this area, as well as southern Nevada.
The peak of the rainfall is anticipated primarily on Sunday and Monday, with areas affected by the most intense downpours possibly experiencing locally higher accumulations of up to 6 inches.
For parts of Arizona, Central California, and northern Nevada, the potential exists for rainfall amounts ranging between 1 to 2 inches.
The consecutive days of heavy rainfall will hinder the ground’s capacity to absorb moisture, progressively heightening the risk of flooding.
Daniel Swain, a climate scientist based at the University of California, Los Angeles, remarked on Wednesday that in certain arid regions of California, there is the potential for an accumulation of “multiple years’ worth of precipitation.”
Among these regions is Death Valley, California, renowned as the Earth’s hottest location. Ordinarily, Death Valley witnesses a meager 2 inches of rainfall throughout an entire year, as per data from the National Weather Service (NWS).
The moisture attributed to Hilary has the potential to release a volume of rain substantial enough to equate to a full year’s worth of precipitation in a single day.
Last year, such extraordinary rainfall had devastating effects in Death Valley. In August, approximately 1,000 individuals found themselves stranded within Death Valley National Park when a 24-hour period brought about 1.46 inches of rain, triggering sudden flooding that obliterated roads and entombed vehicles in debris carried by the inundating waters.
Noteworthy Weather Shifts Emerge for Struggling Southwest
Despite the imminent risk of flooding, the forthcoming rainfall holds the potential to alleviate the persistent drought conditions and replenish groundwater reserves in arid sectors of the Southwest.
This week’s update from the US Drought Monitor revealed an expansion of drought conditions in New Mexico, while California and Arizona maintained their unchanging drought status.
The customary monsoon, which typically provides a substantial portion of the region’s annual rainfall, has been notably absent for much of the summer, causing cities like Phoenix to anxiously await measurable precipitation.
As a combined effect of the anticipated rainfall and heightened cloud cover enveloping the Southwest, a notable cooldown is on the horizon for the upcoming weekend.
Substantial temperature drops are anticipated, with the scorching temperatures that have ranged from the upper 90s to the 110s potentially plummeting by as much as 20 degrees.
Notably, Phoenix could experience a weekend without triple-digit high temperatures for the first time since the middle of June.
Hilary Poised for a Rare Achievement
Although the likelier trajectory for Hilary involves making landfall in Mexico before progressing into California, a unique scenario could emerge.
Should the storm reach California as a tropical storm upon landfall, it would mark a truly exceptional occurrence, unprecedented in nearly 84 years.
Historical data provided by the National Oceanic and Atmospheric Administration (NOAA) reveals that such an event has transpired only twice before in recorded history.
The most recent instance dates back to 1939, involving an unnamed tropical storm, as documented by NOAA records. Beyond that, the sole occurrence of a hurricane making landfall in California is attributed to the San Diego Hurricane in October 1858—a distinctive entry in California’s meteorological history.
Notably, only one other tropical storm, Nora in 1997, managed to sustain its tropical status upon crossing into California.
The existing forecast further predicts an extraordinary development: Hilary maintains its tropical characteristics as it progresses into Nevada.
Such an outcome, if realized, would stand as an unparalleled event in the annals of recorded weather data.