What is a flash drought? An earth scientist explains

Weeds grow on the dried-out floor of the Hoppin Hill Reservoir in North Attleboro, Mass., on Aug. 3, 2022. AP Photo/Charles Krupa

Antonia Hadjimichael, Penn State

Many people are familiar with flash floods – torrents that develop quickly after heavy rainfall. But there’s also such a thing as a flash drought, and these sudden, extreme dry spells are becoming a big concern for farmers and water utilities.

Flash droughts start and intensify quickly, over periods of weeks to months, compared to years or decades for conventional droughts. Still, they can cause substantial economic damage, since communities have less time to prepare for the impacts of a rapidly evolving drought. In 2017, a flash drought in Montana and the Dakotas damaged crops and grasses that served as forage for cattle, causing US$2.6 billion in agricultural losses.

Flash droughts also can increase wildfire risks, cause public water supply shortages and reduce stream flow, which harms fish and other aquatic life. https://cdn.knightlab.com/libs/juxtapose/latest/embed/index.html?uid=f2264358-6060-11ed-b5bd-6595d9b17862 These satellite images show the development of a flash drought in the U.S. Southeast in early September 2019. The event began when a stubborn ridge of high-pressure air hung over the region for several weeks, bringing record-breaking temperatures, dry air and very little rain. Evaporative stress is a measure of how ‘thirsty’ the atmosphere is. Move the slider to see the change in moisture. NASA Earth Observatory

Less rain, warmer air

Flash droughts typically result from a combination of lower-then-normal precipitation and higher temperatures. Together, these factors reduce overall land surface moisture.

Water constantly cycles between land and the atmosphere. Under normal conditions, moisture from rainfall or snowfall accumulates in the soil during wet seasons. Plants draw water up through their roots and release water vapor into the air through their leaves, a process called transpiration. Some moisture also evaporates directly from the soil into the air.

Graphic showing precipitation, evaporation and transpiration between soil and the atmosphere
Water constantly circulates between soil and the atmosphere – sometimes directly, sometimes via plants. USGS

Scientists refer to the amount of water that could be transferred from the land to the atmosphere as evaporative demand – a measure of how “thirsty” the atmosphere is. Higher temperatures increase evaporative demand, which makes water evaporate faster. When soil contains enough moisture, it can meet this demand.

But if soil moisture is depleted – for example, if precipitation drops below normal levels for months – then evaporation from the land surface can’t provide all the moisture that a thirsty atmosphere demands. Reduced moisture at the surface increases surface air temperatures, drying out the soil further. These processes amplify each other, making the area increasingly hot and dry.

Moist regions can have flash droughts

Flash droughts started receiving more attention in the U.S. after notable events in 2012, 2016 and 2017 that reduced crop yields and increased wildfire risks. In 2012, areas in the Midwest that had had near-normal precipitation conditions through May fell into severe drought conditions in June and July, causing more than $30 billion in damages.

New England, typically one of the wetter U.S. regions, experienced a flash drought in the summer of 2022, with areas including Boston and Rhode Island receiving only a fraction of their normal rainfall. Across Massachusetts, critically low water levels forced towns to issue mandatory water restrictions for residents.

Planning for flash droughts in a changing climate

Conventional droughts, like the Dust Bowl of the 1930s or the current 22-year drought across the southwestern U.S., develop over periods of years. Scientists rely on monitoring and prediction tools, such as measurements of temperature and rainfall, as well as models, to forecast their evolution.

Predicting flash drought events that occur on monthly to weekly time scales is much harder with current data and tools, largely due to the chaotic nature of weather and limitations in weather models. That’s why weather forecasters don’t typically make projections beyond 10 days – there is a lot of variation in what can happen over longer time spans.

And climate patterns can shift from year to year, adding to the challenge. For example, Boston had a very wet summer in 2021 before its very dry summer in 2022.

Scientists expect climate change to make precipitation even more variable, especially in wetter regions like the U.S. Northeast. This will make it more difficult to forecast and prepare for flash droughts well in advance.

But new monitoring tools that measure evaporative demand can provide early warnings for regions experiencing abnormal conditions. Information from these systems can give farmers and utilities sufficient lead time to adjust their operations and minimize their risks.

Antonia Hadjimichael, Assistant Professor of Geosciences, Penn State

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Advertisement

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Universe's Way

The Universe is watching you!

𝗦𝗺𝗶𝗹𝗲, 𝗜𝘁𝘀 𝗙𝗿𝗲𝗲 𝗧𝗵𝗲𝗿𝗮𝗽𝘆

Smile, it is the key that fits the lock of everybody’s heart.”

Eat Think Health

We provide useful articles to help you make the right informed decisions to achieve your health, wellness and fitness goals through exercise and eating right.

AM Yoga Space

All About Yoga Practice, Poses, and Benefits

Lazarus Books

Something For Everyone!

Edge of Humanity Magazine

An Independent Non-Discriminatory Platform With No Religious, Political, Financial, or Social Affiliations

Rooster Crows

From the Roof Top

Life Inspiration 4all

understanding Why Mastering the Art of Perseverance and Self-Confidence is the key to success in life.

Blackxreptiles.com

Reptile breeder and blogger

Irish Myths

plumbing the depths of Irish and Celtic mythology, legend, and folklore

Ominous The Spirit

Ominous The Spirit is an artist that makes music, paints, and creates photography. He donates 100% of profits to charity.

Intellectual Shaman

Poetry for Finding Meaning in the Madness

Learn, live and experience East Asian Cultures

East Asian cultures are a whole world of travels, yoga, meditation, Feng Shui, Buddhism, Hinduism and more. Let us share with you the beauty of East Asian Cultures.

Lifesfinewhine

The Life & Ramblings Of A Zillennial

Thomas W. P. Slatin

American Writer, Photographer, and Website Designer. Former career Fire and EMS Lieutenant. She/Her/Hers. Lesbian.

Art By An Ant

dedicated to everyone who wonders if i'm writing about them. i am.

Miracle of Manifestation

Powerful Laws of Attraction and Manifestation

TechWordly

Best Tech Gadgets Advise

G-FX.NET

Digital Multimedia and Search Engine Optimization

Awake Your Inner Dragon

Combine the mental (mindset), the physical (exercise) & the spiritual (meditation) together to Awake Your Inner Dragon.

Churape's Dungeon and Stuff

Movie, TV, and Game Reviews

SoundEagle 🦅ೋღஜஇ

Where The Eagles Fly . . . . Art Science Poetry Music & Ideas

Golf Swing

Improve Your Game

RJB Press

Thoughts, Opinions and More

Stress Free You

My WordPress Blog

Smith Shine Poetry

When the Soul Cried Out for Meaning

Inner Peace

True wealth is the wealth of the soul

Healthy PRO

Healthy Lifestyle Review

medicalparkphysio.wordpress.com/

Commitment to Better Physiotherapy

Ray Barbier

Random Thoughts of an Average Joe

thedihedral.wordpress.com/

Climbing, Outdoors, Life!

The Alchemist's Studio

Raku pottery, vases, and gifts

Some View on the World

With previous posting of "Our World" on Blogger

Dovestar's Desk

Just another RJB Press site

%d bloggers like this: