A lot can go wrong when hurricanes stall. Their destructive winds last longer. The storm surge can stay high. And the rain keeps falling…
Research shows that stalling has become more common for tropical cyclones in the North Atlantic since the mid-20th century and that their average forward speed has also slowed.
The Arctic has been warming about twice as fast as the mid-latitudes, where most of the U.S. is located. That’s changing the distribution, or gradient, of temperature between the Arctic and the mid-latitudes. And that can affect the steering currents, such as those associated with the Bermuda high.
On average, the forward speed of hurricanes has been slowing down. Simulations of tropical storm behavior have suggested that this slowing will continue as average global temperatures warm, particularly in the mid-latitudes…
A warmer atmosphere also means storms can tap into more moisture. As temperature increases, it’s easier for water to evaporate into vapor…If a storm slows, and if it has access to more moisture, it can dump more rain and produce a greater storm surge due to the slow motion.
RTFA. Even more interesting, mostly unnerving, factors affecting the course of hurricanes to come.
Recent Atlantic ocean warming unprecedented in nearly 3,000 years https://www.eurekalert.org/pub_releases/2020-10/uoma-rao101420.php
Fluctuations in sea surface temperatures, known as the Atlantic Multidecadal Oscillation (AMO), are also linked to other major climatic upheavals such as droughts in North America and the severity of hurricanes. However, because measurements of sea surface temperatures only go back a century or so, the exact length and variability of the AMO cycle has been poorly understood.
“Annually resolved Atlantic sea surface temperature variability over the past 2,900 y” https://www.pnas.org/content/early/2020/10/06/2014166117
The 2020 hurricane season continues its relentless onslaught as Eta, the 28th named storm of the season, lashes Central America with torrential rains and whipping winds. Typically Central America is a graveyard for hurricanes — but not Eta. Increasingly, forecasters are concerned Eta will reemerge over the warm Caribbean waters and then head toward Florida this weekend.
Zeta was the 11th named storm and 6th hurricane to make U.S. landfall in 2020. Both are seasonal records (the 6 hurricane landfalls ties with 1985 and 1886). Louisiana is the first state with five named storm landfalls in a season. 2020 U.S. TC damage costs already >$30B. https://www.cbsnews.com/news/eta-could-hit-south-florida-may-become-hurricane-again/
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“The twisty, curvy forecast path of Eta over the next several days is a reminder that hurricane paths often aren’t relatively straight lines.” (slideshow) https://weather.com/storms/hurricane/news/2020-11-05-strangest-hurricane-tracks
Nov 15, 2020: “The storm known as Iota strengthened into a hurricane early Sunday and is expected to slam into Central America early next week — the very region already devastated by Hurricane Eta earlier this month — forecasters say.” https://www.cnn.com/2020/11/15/weather/iota-storm-sunday/index.html
Iota ‘strongest hurricane of 2020 Atlantic season’ with 155 mph winds https://www.sun-sentinel.com/news/weather/hurricane/fl-ne-tropical-storm-iota-caribbean-sunday-print-111520-20201115-lh73sl3jrrhyxax74snx4n23ee-story.html
Iota could reach the Pacific Ocean, becoming a rare crossover storm that gets renamed. Iota was about 145 miles southeast of the border between Nicaragua and Honduras, moving west at 10 mph, as of 7 a.m. Monday.
(11/15/20) “Iota is not expected to regenerate over the Pacific Ocean, and there is no model support indicating that Iota might move northward into the Gulf of Mexico and threaten the U.S., as so many other storms this year have done.” https://yaleclimateconnections.org/2020/11/hurricane-iota-rapidly-intensifies-ahead-of-expected-landfall-near-nicaragua-honduras-border/
“Scientists link record-breaking hurricane season to climate crisis : Evidence is not so much in the number of tropical storms the Atlantic has seen, but in their strength, intensity and rainfall” https://www.theguardian.com/environment/2020/nov/15/scientists-link-record-breaking-hurricane-season-to-climate-crisis?CMP=share_btn_tw
“Hurricanes might not be losing steam as fast as they used to : Extra water vapor in the storm may help sustain it after landfall.” https://arstechnica.com/science/2020/11/hurricanes-might-not-be-losing-steam-as-fast-as-they-used-to/
“Lots of attention is given to the effects of climate change on tropical cyclones, much of it focusing on effects that are dead obvious. Projections indicate increased intensity among the strongest storms, for example, and increases in rainfall and storm surge are unavoidable consequences of warmer air holding more moisture and sea level rise, respectively.
But a new study by Lin Li and Pinaki Chakraborty at the Okinawa Institute of Science and Technology Graduate University focuses on a less-than-obvious question: what happens to hurricanes after landfall in a warming world? Once a storm moves over land, it loses the water vapor from warm ocean waters that fuel it, so it rapidly weakens. The total damage done depends in part on how quickly it weakens.”
See also “Tropical cyclones are already getting stronger, new dataset shows” https://arstechnica.com/science/2020/05/tropical-cyclones-are-already-getting-stronger-new-dataset-shows/