October aims to break U.S. dry and warm records » Yale Climate Connection

Will this turn into a flash drought?

Meteorological drought is simply a lack of normal precipitation and can occur even in the absence of unusually warm temperatures. Sudden drought is characterized by a particularly rapid or intensified drought situation (For example, agricultural or hydrological droughts, related to insufficient soil moisture or water storage). Meteorological droughts can occur without unusually warm temperatures, but droughts Influence Human-induced warming has intensified the incidence of “heat droughts”.

Read: Climate change and drought: What’s the connection?

Flash droughts are often caused by extreme drought during the warm, sunny months of spring or early summer, resulting in high evapotranspiration (the release of water by plants and soil). Sudden droughts at this time of year are particularly damaging to warm-season crops because they rob crops of moisture at critical times.

This month's unusual mix of dryness, warmth, and cloudlessness could have easily triggered a widespread, sudden drought had it occurred in May or June, but October's less intense sunshine mitigated the effects of dryness on the landscape. Still, by at least one definition, much of the United States from Wyoming to New Jersey is now in a flash drought zone (see Figure 3).

A 2019 paper in the journal Atmosphere, “Characteristics of sudden droughts based on the U.S. Drought Monitor,” defines sudden drought as a degradation of at least two categories in the U.S. Drought Monitor rating over a four-week period. As of the Drought Monitor released on October 24, many areas of the central United States now qualify for flash drought, as shown in Figure 3 above. Overall, drought has intensified across much of the country's central third.

With the onset of fall drought, most summer crops in the U.S. are at or near the harvest stage, so rain-free weather is actually beneficial to the harvest.

If you happen to spot a cloud within our 300 miles, please let us know. pic.twitter.com/Z8xnmn1hCK

— NWS Louisville (@NWSLouisville) October 20, 2024

A disturbing precedent: October 1952

Of the more than 1,500 months in NOAA's database since 1895, only October 1952 has a clear advantage in terms of nationwide drought in October 2024.

According to climatologist Brian Brettscheider, precipitation in the contiguous United States this month totaled about 0.57 inches through October 21 (see embedded post below). Typically, yields range from two to three inches per calendar month. A few unusually dry months yielded about an inch, including 0.95 inches in October 1965 and November 1917. NOAA's data is only 0.54 inches.

Given the massive forecast through October 31, this month is likely to be the driest month in U.S. history, second only to October 1952.

As it turns out, October 1952 was in the early stages of the Great American Drought of the 1950s. In some areas of the Southern Plains, the event actually surpassed the Dust Bowl of the 1930s in terms of lack of precipitation and intense heat, forcing the closure of more than 100,000 farms and ranches in Texas alone and displacing thousands of people from the land.

A 2016 paper by John Wiener and co-authors, “No Bark Bite: How Socioeconomic Contexts of Droughts in the United States during the 1950s minimized responses to multi-year extreme climate events.” Due at least in part to innovations introduced after the catastrophic Dust Bowl, the droughts of the 1950s had a much smaller impact on agricultural output and the nation's food supply than the droughts of the 1930s. According to Wiener and co-authors, “Basic measures worked: urban reservoirs, well-designed public water supplies, protective farm policies including aid, insurance and price supports, and efforts to stop farming the most vulnerable lands.”

Long-range models predict major pattern changes during the first week of November that could bring significant precipitation to the Pacific Northwest and Mississippi Valley. Remote ensemble output also repeatedly suggests that a tropical cyclone may form in the western Caribbean during the first week of November. Typically, systems like this stay in the southern United States late in the season, but in this case, moving north into the United States is not out of the question, so the situation is certainly one to watch. It remains to be seen whether these one-time events will change the trajectory of much of the U.S. drought this fall (even if parts of the Southeast are hit by hurricanes and receive significant rainfall).

La Niña is closely associated with droughts in the United States, with a strong La Niña lasting two years at the center of the 1950s drought from mid-1954 to mid-1956. The strong La Niña of 2020-2022 did not cause equally severe droughts in the United States, and experts from the National Oceanic and Atmospheric Administration (NOAA) and the International Research Institute for Climate and Society now expect only weak La Niña events during 2024-25 . But with the prerequisites for widespread drought impacts now in place, it's time to start paying close attention.

One year ago tonight: Otis->Cats. 5

today: #christie -> Cat. 5

It would be nice if Otis could be 🐠 too. pic.twitter.com/7Kjm2YNBG1

— Jonathan Edelman (@wxjerdman) October 24, 2024

Christie reaches level 5 in Northeast Pacific

In the remote Northeast Pacific, Hurricane Christie went from the bottom of the Category 1 range on Tuesday to the top of the Category 4 hurricane range in just 24 hours before becoming Earth's fourth Category 5 storm of 2024 at 5 p.m. ET on Thursday . Other Category 5 storms on Earth so far this year include two Atlantic hurricanes, Beryl and Milton, and one western Pacific typhoon, Yagi.

The global average for the entire calendar year from 1990 to 2023 is 5.3 Cat 5s, so we're not even close to the average so far this year. The record was 12 Cat 5s in one year, set in 1997.

Jeff Masters contributed to this article. Special thanks to Christopher Burt and Jasper Deng for their assistance with this article.