Hurricane “Hilary” [Eastern Pacific]

[GordMay]

Hurricane “Hilary” strengthened into a major Category 3 hurricane, Thursday evening, off Mexico’s Pacific coast, and it could bring heavy rain to the southwestern U.S. by the weekend.

The storm was expected to grow into a Category 4 hurricane today [Friday, Aug 18], while on a projected path, that threatened landfall on the central Baja California peninsula, by Sunday, or possibly keep just offshore, while heading for Southern California.

No tropical storm has made landfall in Southern California, since Sept. 25, 1939, according to the National Weather Service.

Hurricane “HILARY” ➥ https://www.nhc.noaa.gov/archive/202...adv.008.shtml?

[GordMay]

As of 600 AM MDT (1200 UTC):

Maximum sustained winds are near 145 mph (230 km/h) with higher
gusts. Hilary is a category 4 hurricane on the Saffir-Simpson
Hurricane Wind Scale. Fluctuations in intensity are likely over the
next day or so. Weakening is expected to begin by Saturday, but
Hilary will still be a hurricane when it approaches the west coast
of the Baja California peninsula Saturday night and Sunday. Hilary
is expected to weaken to a tropical storm by Sunday afternoon before
it reaches southern California.
Advisory 8a ➥ https://www.nhc.noaa.gov/text/refres...l/181135.shtml

Key messages ➥ https://www.nhc.noaa.gov/refresh/gra...sages#contents

[JPA Cate]

There was a hurricane that did go into So Cal, perhaps prior to 1900, and then, it crossed east to the Atlantic. That was a huge distance, and a very unusual path.

I'm sure the folks in the San Diego area will start paying attention as it approaches.

Hurricane prediction is hard to get right, but if it goes ashore in Baja, will it not turn to cross the peninsula, re-charge over the Golfo de California, and then cross Mexico?

Ann

[GordMay]

Originally Posted by JPA Cate

... Hurricane prediction is hard to get right, but if it goes ashore in Baja, will it not turn to cross the peninsula, re-charge over the Golfo de California, and then cross Mexico?
Ann

Hurricane Hilary’s winds strengthed, from 40 mph, to more than 100 mph, in about 12 hours, last Thursday, more than double the rate, that defines rapid intensification*.
That development matches a global trend, of hurricanes intensifying more quickly, since 1991, which is probably caused by warming oceans, hurricane researchers wrote, in a 2020 study [1].

*When a hurricane undergoes rapid intensification, its maximum sustained winds increase, by at least 35 mph, in 24 hours or less.

Most major hurricanes [Category 3 or higher] undergo rapid intensification at some point, a 2022 study [2] shows. Of 104 such storms, in the North Atlantic, since 1990, 88% fit the bill.

Because heat helps fuel storms, higher sea surface temperatures, and high ocean heat content, play huge roles in rapid intensification. So, as the climate crisis forces up ocean temperatures, rapid intensification becomes more likely, pushing storms to explode, at a rapid pace, into deadly hurricanes.

Scientists are confident that hurricanes are on track to get increasingly stronger, with rising mean global temperatures, meaning more rapid intensification, along with increased rainfall.

Hurricanes are not just intensifying faster, and dropping more rain. Because of global warming, their destructive power persists longer, after reaching land, increasing risks, to communities farther inland, that may be unprepared for devastating winds and flooding.

Hurricanes hold more moisture, in a warmer climate, because the atmosphere can hold about 7 percent more water, for every 1.8 degrees Fahrenheit warming. Part of a hurricane’s total energy is stored in the water it carries, and that extra fuel helps storms overpower the weakening effect of friction, over land.

That shift was underlined, by an analysis of Atlantic hurricanes, that made landfall between 1967 and 2018. The study [3], published in Nature, showed that, in the second half of the study period, hurricanes weakened almost twice as slowly, after hitting land.
“As the world continues to warm, the destructive power of hurricanes will extend progressively farther inland,” the researchers wrote, in their report [3].

Paleoclimate records show how hurricane paths have shifted, over centuries and millennia, which may also affect their strength after landfall, because their, path over the ocean, also determines how much moisture they gather. In a 2016 study [4], in Scientific Reports, Baldini found that hurricane paths have changed significantly, in the last 450 years.

[1] “Global increase in major tropical cyclone exceedance probability over the past four decades” ~ by James P. Kossin et al
➥ https://www.pnas.org/doi/10.1073/pnas.1920849117

[2] “Trends in Global Tropical Cyclone Activity: 1990–2021" ~ by Philip J. Klotzbach et al
➥ https://agupubs.onlinelibrary.wiley....9/2021GL095774

”... Global hurricane counts and Accumulated Cyclone Energy (ACE) have significantly decreased since 1990 likely due to a trend toward La Niña

Short-lived named storms, extreme rapid intensification events (50+ kt day−1) and global damage have increased significantly from 1990 to 2021

Decreasing trend in global hurricanes and ACE is primarily driven by downturn in western North Pacific activity

Plain Language Summary
This study investigates 1990–2021 global tropical cyclone (TC) activity trends, a period characterized by consistent satellite observing platforms. We find that fewer hurricanes are occurring globally and that the tropics are producing less Accumulated Cyclone Energy—a metric accounting for hurricane frequency, intensity, and duration. This decreasing trend has primarily been driven by a significant downturn in western North Pacific TC activity—the tropical basin that typically is the most active. Short-lived named storms (TCs lasting ≤2 days) and the number of times that TCs quickly strengthen (≥50 kt in 24 hr) have increased significantly since 1990. Identifying more short-lived named storms is likely due to improved sensors, while increases in rapidly intensifying storms may be driven by more favorable conditions. Global damage from TCs has significantly increased as well, likely largely due to population growth and increased value of coastal assets (physical structures and non-physical risk exposure). The trend during the past 32 years toward a more La Niña-like environment has favored North Atlantic TC activity and suppressed North and South Pacific activity. Since the Pacific Ocean normally generates much more activity than the Atlantic, global TC activity has generally trended downward...”

[3] “Slower decay of landfalling hurricanes in a warming world” ~ by Lin Li & Pinaki Chakraborty
➥ https://www.nature.com/articles/s41586-020-2867-7

[4] “Persistent northward North Atlantic tropical cyclone track migration over the past five centuries” ~ by Lisa M. Baldini et al
➥ https://www.nature.com/articles/srep37522

[GordMay]

If the storm makes landfall in Southern California as a tropical storm, it will be the first one in 84 years, according to the National Weather Service. And the storm could provide heavy rainfall and flash floods, according the NHC.

Forecast rainfall totals of 2-4 inches, with some amounts of up to 8 inches, will be possible across portions of Southern California and Southern Nevada. Between 2-3 inches of rain could also fall across portions of western Arizona.

[GordMay]

Late on Sept. 25, 1939, a violent storm lashed Southern California, sinking boats, flooding mountain resorts, and killing nearly 100 people. It was the last tropical cyclone to make landfall, in the region.

The 1939 storm [“the Lash of St. Francis”, or “El Cordonazo”], which made landfall in Long Beach, Calif., tore through Los Angeles County and the surrounding area, destroying coastal homes, cutting power and disrupting rail and highway traffic, according to an article published in The New York Times the next day.

That fall, Southern California was suffering from an intense heat wave, with temperatures reaching as high as 107 degrees, when the warning of a growing storm, started to ripple through the coast. The hurricane began forming around Sept. 15, off the coast of Central America, and made its way slowly toward California. Its intensity was downgraded, to a tropical storm, by the time it started raining in Los Angeles, on the evening of Sept. 24, but the winds, that were about to hit California, hadn’t been experienced in decades.

Nearly 100 people were killed. Some of the victims drowned at sea, while others died in flooding.

More than a dozen boats were declared missing, and the wreckage of an 80-foot yacht washed up, near Huntington Beach, a usually picturesque surf spot. Around 200 people had to be rescued from wrecked leisure and fishing boats. Twenty-three people drowned when the sport fishing vessel, “Spraya”, capsized, just 500 feet from a pier, at Point Mugu, near Oxnard. Several bodies were recovered from the water, including those of a man and a woman that washed ashore.

In Los Angeles, 5.41 inches of rain fell in 24 hours, the heaviest September rain in the city’s history at the time. A deluge in the Coachella Valley washed out train tracks, and destroyed 70 percent of the region’s date crop. The overall damage was estimated to be around $2 million, the equivalent of around $44 million, in today’s dollars.

Other tropical storms have brought tropical storm-force winds to the Southwestern United States, but just two have made landfall in California. Besides the 1939 storm, the only other tropical storm to make landfall, in the state, was on Oct. 2, 1858, when a hurricane shook San Diego, damaging homes, uprooting trees, and causing inland flooding. The Daily Alta California described it as “one of the most terrific and violent hurricanes ever noted,” according to a National Oceanic and Atmospheric Administration paper on the event.

Such events are extremely unusual in the region, because the dry air, cool water, and wind conditions, off California’s coast, tend to break up hurricanes.

But in the case of “Hilary”, slightly warmer waters, caused by El Niño, are helping to weaken the storm more slowly, while pressure systems are pushing the storm north, toward land.

“A History of Significant Weather Events in Southern California” ~ by NOAA
➥ https://web.archive.org/web/20080229...herhistory.pdf

“THE SAN DIEGO HURRICANE OF 2 OCTOBER 1858" ~ by MICHAEL
CHENOWETH AND CHRISTOPHER LANDSEA
➥ https://www.aoml.noaa.gov/hrd/Landse...ethlandsea.pdf

[donradcliffe]

So we may conclude that the last global warming was in 1939, and the one before that was 1858. Maybe, just maybe, global warming does not correlate with consumption of fossil fuels.

I just competed two deliveries of Transpace race boats back to California. The California waters were noticeably warmer at night than the usual below 60 degrees. A little warming is not a bad thing offshore at night.

[skipperpete]

1899 was the year that Australia had its worst cyclone, a Cat 5 called Mahina and we haven’t had one like it since, I fervently hope Hilary stays lower than a cat 4 and preferably decays into a rain depression.
It seems like cyclones and hurricanes have diminished in strength over the years but the current population density increases destruction when the lesser tropical revolving storms make landfall. The US has had 39 recorded cat 5’s ( according to Wiki)

[Ryban]

Originally Posted by skipperpete

It seems like cyclones and hurricanes have diminished in strength over the years but the current population density increases destruction when the lesser tropical revolving storms make landfall. The US has had 39 recorded cat 5’s ( according to Wiki)

Data seems to suggest otherwise though, at least for the Atlantic basin: https://www.nature.com/articles/s41467-021-24268-5

[gonesail]

it looks like a nothing burger on the radar

[Ryban]

Yeah it's hot colder water so it's rapidly falling apart, but it's packing a ton of moisture.

[JPA Cate]

As of this morning, it was forecast to maintain its course, and diminish back down to a tropical storm --no longer a hurricane-- but she'll keep the name, and everyone from San Diego to Fresno will be wondering about the rainfall. In some places, the sewage shares the storm drains, so there will be some closed beaches for a while, too.


Ann

[GordMay]

Hilary live update Aug. 20, 2023, 4:16 PM EDT:
➥ https://www.nbcnews.com/news/weather...nia-rcna100823

[Tin Tin]

1972 song by Albert Hammond



"Seems it never rains in southern California
Seems I've often heard that kind of talk before
It never rains in California
But girl, don't they warn ya?
It pours, man, it pours"

[El Pinguino]

It doesn't take much rain to cause havoc in places that don't get much rain. In 2015 much of the Atacama experienced a storm that dumped between 1 and 2 inches in areas that were used to getting not very much. That storm caused total havoc.

Wettest month in Iquique f'rinstance is January with the average January rainfall being 0.0mm . The infrastructure just isn't designed to deal with 'rain' events.

San Diego gets an annual average of about 10 inches.

https://floodlist.com/america/chile-...gasta-coquimbo