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2020 officially saw a record number of $1 billion weather and climate disasters.
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Just some info from the top guys at the NHC. It also applies to such things as detecting rapid intensification and indeed maximum intensities.
Was 2020 a Record-Breaking Hurricane Season? Yes, But. . . « Inside the Eye
Take Aways
The answers and conclusions to “Was 2020 a Record-Breaking Hurricane Season? Yes, but…”:
Doubling in the number of named storms over a century is very likely due to technology change, not natural or man-made climate change;
2020 set a record for number of named storms, but given the limitations in our records it is possible that other years (such as 1887) were just as active for long-lived named storms; and
The boost in average or “normal” conditions from 12 to 14 named storms is due to a combination of a busy era that began in 1995 as well as the ability of the National Hurricane Center to observe and accurately diagnose more weak, short-lived named storms than had been done previously, mostly due to technology advancements.
Some key sections:
For overall monitoring of tropical storm and hurricane activity, tropical meteorologists prefer a metric that combines how strong the peak winds reached in a tropical cyclone, and how long they lasted – called Accumulated Cyclone Energy or ACE[2]. By this measure, 2020 was extremely busy, but not even close to record breaking. In fact, with a total ACE of 180 units, 2020 was only the 13th busiest season on record since 1878 with seasons like 1893, 1933, 1950, and 2005 substantially more active than 2020. One can also see that while there is a long-term increase in recorded ACE since the late 1800s, it’s quite a bit less dramatic than the increase seen with named storms. There also is a pronounced busier/quieter multi-decadal (40- to 60-year) cycle with active conditions in the 1870s to 1890s, late 1920s to 1960s, and again from the mid-1990s onward. Conversely, quiet conditions occurred in the 1900s to early 1920s and 1970s to early 1990s.
So why would the record for named storms be broken in 2020, while the overall activity as measured by ACE is not even be close to setting a record?
The answer is very likely technology change, rather than climate change.
Such technology, though, was not available back at the advent of the U.S. Signal Service’s tropical monitoring in the 1870s. Without these sophisticated tools, meteorologists in earlier times not only had difficulty in forecasting tropical cyclones, but they also struggled in even knowing if a system existed over the open ocean. In the late 19th and early 20th Centuries, the only resource hurricane forecasters could use to monitor tropical cyclones were weather station observations provided via telegraph. Such an approach is problematic for observing – much less forecasting – tropical cyclones that develop and spend most of their lifecycle over the open ocean. Here’s a timeline of critical technologies that have dramatically improved tropical meteorologists’ ability to “see” and monitor tropical cyclones:
The upshot of all of these advances in the last century is much better identification of the existence of tropical cyclones and their strongest winds (or what meteorologists call “Intensity”). So, the further one goes back in time, the more tropical cyclones (and portions of their life cycle) were missed, even for systems that may have been a major hurricane.
HURDAT2 – our Atlantic hurricane database – is an extremely helpful record which is a “by-product” of NHC’s forecasting operations, but it is very deficient for determining real long-term trends.
In research that the lead author had investigated (Chris Landsea and company in 2010’s Journal of Climate), we discovered that weak, short-lived (lasting less than or equal to two days) named storms – aka “Shorties” – had shown a dramatic increase in occurrence over time. There were only about one a year in HURDAT2 up until the 1920s, about 3 per year from the 1930s to the 1990s, and jumping up to around 5 per year since 2000.
Of the 30 named storms in 2020, seven were Shorties and a few more were just longer than two days in duration. Of these seven Shorties, four are very unlikely to have been “named” before around 2000: Dolly, Edouard, Omar, and Alpha. These and other weak, short-lived systems since 2000 have been observed and recognized as tropical storms due to new tools available to forecasters including scatterometers, Advanced Microwave Sounding Units, the Advanced Dvorak Technique, and the Cyclone Phase Space diagrams.
The resulting final time series shows tremendous variability, with highest values of 23 in 2020 and 20 in 1887 and 2005, and lowest values of 2 in 1914, and 3 in 1925, 1982, and 1994. Overall, there remains a modest upward trend in the database over the entire time series superimposed with quasi-cyclic variations seen in the ACE data as was discussed earlier: higher activity in the late 1800s, mid-1900s, and from the mid-1990s onward, but lower activity in the early 1900s, and in the 1970s to early 1990s. These cycles of higher and lower activity have been linked to a natural phenomenon called the Atlantic Multidecadal Oscillation (AMO) (see paper by Stan Goldenberg, Chris Landsea, and colleagues in 2001’s Science). Recent controversial research, however, is calling into question whether the AMO actually exists (see paper by Michael Mann and company in 2021’s Science). Regardless of the validity of the AMO, the bottom line is that the doubling in the number of named storms over a century is very likely due to technology change, not natural or man-made climate change.
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Bad flooding in New York overnight, but despite what I just listened to on RTÉ radio earlier, the rainfall was not of record proportions. A max of 8.92" in New York and 9.91" in New Jersey.
NEW YORK... STATEN ISLAND 8.92 BROOKLYN 7.76 MIDTOWN MANHATTAN 7.49 FORDHAM 7.38 NEW YORK CITY, CENTRAL PARK 7.19 FLUSHING 6.90 NEW YORK, LA GUARDIA AIRPORT 6.89 HARLEM 6.00 MONTGOMERY, ORANGE COUNTY AIRPORT 5.24 WHITE PLAINS 4.28 HARTFORD, HARTFORD-BRAINARD AIRPORT 2.73 ALBANY INTL AIRPORT 1.06 ISLIP, LONG ISLAND MAC ARTHUR APT 0.81 NEW JERSEY... RINGOES 9.91 CARTERET 9.31 HOPEWELL TWP. 2.4 NW 9.13 WARREN TWP 1.3 W 8.94 HARRISON 8.61 WALDWICK 8.59 NEWARK 8.44 PASSAIC 8.43 NEWARK INTL AIRPORT 7.81 LINDEN 6.72 BRIDGEWATER 3 NNW 6.58 WHITEHOUSE STATION 6.42 TRENTON, MERCER COUNTY AIRPORT 5.41
Below are the storm record storm totals from the period 1900-2020 for the New York/Newark area (source). Again, the worst were back in the good ole days of ideal climate.
The state records are 24.00" (1940) and 11.70" (Labor Day, 1935) for New York and New Jersey, respectively.
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