METEO 3 Lesson 9 Images

Lesson 9: Severe Weather

 

Flash Flooding

30-year period from 1987 to 2016, more deaths were attributed to flooding

Bar chart of weather fatalities in 2016 comparing 10-year and 30-year averages by event type.
30-year period from 1987 to 2016, more deaths were attributed to flooding
Text description of the 30-year period from 1987 to 2016, more deaths were attributed to flooding image.

The image is a bar chart titled "Weather Fatalities 2016" against a blue textured background. The chart compares the number of fatalities caused by different weather events for 2016, the 10-year average (2007-2016), and the 30-year average (1987-2016). The categories include Flood, Lightning, Tornado, Hurricane, Heat, Winter, Cold, Wind, and Rip Currents. Each category has three vertical bars representing different averages: red for 2016, gray for the 10-year average, and yellow for the 30-year average. The chart shows that floods had the highest fatalities in 2016 with 126 deaths, while rip currents had the least, with N/A on 10-year and 30-year averages. A legend in the upper right corner clarifies the color coding of the bars. The background includes a partial logo of the National Weather Service in the top right corner.

Credit: CREDIT_HERE

which juts upward at very steep angles

A winding road with cars passing through a narrow canyon with jagged rock walls.
which juts upward at very steep angles
Text description of the which juts upward at very steep angles image.

The image showcases a winding road cutting through a narrow canyon with towering rock walls. The road has two lanes, marked by a yellow centerline, and is bordered by a wooden guardrail. Several vehicles, including a red car and a black SUV, are visible driving along the road. The canyon’s steep cliffs are composed of rugged, jagged rock formations with a grayish hue, interspersed with patches of greenery. The sky above is overcast, with a hint of clouds.

Credit: CREDIT_HERE

radar loop from 00Z to 06Z on May 27, 2007 (0:04)

radar loop from 00Z to 06Z on May 27, 2007
Text description of the radar loop from 00Z to 06Z on May 27, 2007 (0:04)

The loop is a weather radar map displaying precipitation across a geographical region. The region is outlined with state borders, indicating it includes parts of Oklahoma, Texas, and New Mexico. The map features various colors, with clusters of bright green, yellow, orange, and red, indicating areas of precipitation intensity. Yellow and red areas suggest heavier rainfall, concentrated in a vertical band stretching from the center to the bottom. Smaller clusters of green and blue are scattered around the main band, suggesting lighter rainfall. The background is black, enhancing the visibility of the colored precipitation data.

Credit: CREDIT_HERE

moist air is forced to rise over a front

Weather map showing a front line with a low-level jet and multicolored weather system.
moist air is forced to rise over a front
Text description of the moist air is forced to rise over a front image.

The image is a weather map illustrating a region in the central United States, including parts of Kansas, Missouri, Iowa, and Nebraska. It features a multicolored weather system shaded in hues of green, yellow, and red, representing varying intensity levels, spreading across multiple states. A series of alternating red semicircles and blue triangles form a weather front line, oriented horizontally through the center of the map. Below this line, a broad green arrow labeled "Low-Level Jet" curves upward into the weather system, indicating wind movement direction.

Credit: David Babb @ Penn State is licensed under CC BY-NC 4.0(opens in a new window)

 

Hail

rip the siding right off a building

Side of a house with chipped white siding revealing a dark underlayer, cars in front.
rip the siding right off a building
Text description of the rip the siding right off a building image.

The image shows the side of a house with white siding that has been heavily chipped, revealing a dark underlayer. The siding is lined horizontally across the wall. The roof is slanted and covered with brown shingles. In the foreground, partially visible, are several cars parked near the house. The yard is bordered by a wooden fence, and the ground appears to be covered with some leaves or debris. In the background, leafless trees are visible against a clear sky.

Credit: National Weather Service, Lubbock, Texas

severely damage crops

Field of damaged green plants with hailstones on the ground.
severely damage crops
Text description of the severely damage crops image.

The image shows a field of green plants that appear damaged. The plants are bent over and have torn leaves, likely due to a weather event like hail. The ground is covered in small, white objects, resembling hailstones, indicating recent hailstorm activity. The plants are densely spaced and cover a large area, suggesting an agricultural setting.

Credit: National Weather Service, Hastings Nebraska

significant accumulations of hail

A rural road covered in hail with tire tracks showing the asphalt, surrounded by flat grassland under an overcast sky.
significant accumulations of hail
Text description of the significant accumulations of hail image.

The image shows a rural road covered with a layer of hail, stretching diagonally from the bottom left to the top right. The road has distinct tire tracks, where the black asphalt is visible, flanked by thick layers of white hail on either side. The surrounding terrain is flat, with brown grassland extending across the background. The sky is overcast, with hints of blue and some white clouds, creating a dull atmosphere. A tall communication tower is visible in the distance on the right side of the image.

Credit: National Severe Storms Laboratory

the size of a quarter

A hand holding a white hailstone and a U.S. quarter coin for size comparison.
the size of a quarter
Text description of the the size of a quarter image.

The image shows an open hand resting against a dark background. In the palm are two objects: a smooth, rounded piece of white hail on the left, and a U.S. quarter coin on the right. The hailstone appears to be approximately the same size as the coin, indicating a significant hail size. The skin tone of the hand is light, with visible creases on the palm. The background is dark and slightly blurred, with what appears to be marble-like surfaces partially visible.

Credit: National Weather Service

graupel

Close-up of graupel scattered on brown twigs and wood chips.
graupel
Text description of the graupel image.

The image shows a close-up view of a ground surface covered with a mix of graupel and brown twigs and wood chips. The graupel is small, round, and uniformly scattered across the entire area. The brown twigs and wood chips are irregularly shaped and vary in size, creating a textured, natural background. The contrast between the bright white graupel and the darker, earthy tones of the wood is prominent, highlighting the graupel against the surface.

Credit: CREDIT_HERE

areas of very high reflectivity aloft in a thunderstorm

Radar cross-section showing a hail signature in a weather scan.
areas of very high reflectivity aloft in a thunderstorm
Text description of the areas of very high reflectivity aloft in a thunderstorm image.

The image is a radar cross-section labeled "Composite Refl," showing a range of colored blocks representing different reflectivity levels in a weather radar scan. The x-axis represents the distance in nautical miles, ranging from 0 to 25, while the y-axis represents height in thousands of feet (kft), ranging from 0 to 42. The colors on the radar image range from blue through green, yellow, and red, with a small white area circled in pink, labeled "Hail Signature," indicating a significant weather event. The colors indicate different levels of precipitation, with red and white areas suggesting heavy precipitation and potential hail. Below the main section, a timeline is shown with a timestamp: "05/05/0 19:51:02 UTC Vol:236" and a legend explaining the distances in nautical miles.

Credit: CREDIT_HERE

supercell in Vivian, South Dakota

Weather radar map showing intense supercells with a color-coded intensity scale.
supercell in Vivian, South Dakota
Text description of the supercell in Vivian, South Dakota image.

The image is a weather radar map displaying storm intensity using a color-coded scale on the left ranging from dark blue to dark red. In the lower left, a large, intense supercell is marked with hues from bright red to green, indicating high severity. Another cluster of storm activity is seen towards the top, extending into the center-right. Areas of lighter blue and green surround these intense clusters, indicating lower intensity precipitation. The map has a brown background with faint grid lines and a circular label “KABR” at the upper right.

Credit: CREDIT_HERE

diameter of a whopping eight inches

Large hailstone on textured brown fabric with measuring tape beneath, marked from 11 to 13 inches.
diameter of a whopping eight inches
Text description of the diameter of a whopping eight inches image.

The image shows a large, irregularly-shaped hailstone placed on a surface covered with a textured, brown fabric. The hailstone is translucent with rough, jagged edges and an uneven surface, giving it a spiked appearance. A white measuring tape with black markings is placed horizontally beneath the hailstone, indicating its size against the nearest inches marked as 11 to 13. The background fabric has a subtle, fuzzy texture.

Credit: National Weather Service

 

Downbursts

all thunderstorms have downdrafts

Diagram of a cumulonimbus cloud showing updrafts and downdrafts with a cold pool.
all thunderstorms have downdrafts
Text description of the all thunderstorms have downdrafts image.

The image illustrates the mature stage of a cumulonimbus cloud with both updraft and downdraft. The cloud is depicted in white against a gradient blue and purple sky. On the left side, orange arrows indicate the upward movement (updraft) within the cloud. To the right, blue arrows demonstrate the downward movement (downdraft). Below the downdraft, there is a shaded area labeled "cold pool" near the ground, representing cooler air spreading outward. The ground is depicted as a green horizontal surface, with a brown gradient indicating soil.

Credit: David Babb @ Penn State is licensed under CC BY-NC 4.0(opens in a new window)

hundreds of fallen trees lay in a divergent starburst pattern

Aerial view of a forest with many trees lying in the same direction, marked by black arrows, indicating wind damage. Power lines are visible above a nearby green field.
hundreds of fallen trees lay in a divergent starburst pattern
Text description of the hundreds of fallen trees lay in a divergent starburst pattern image.

The aerial image shows a swath of forested land where numerous trees have been uprooted and lie on their sides. The trees are predominantly oriented in a uniform direction, suggesting they have been felled by a strong force, such as wind. Black arrows are superimposed onto the image, all pointing in the same direction as the fallen trees, indicating the path of the force. In the upper left, a contrasting patch of bright green grass can be seen, separated by a straight row of power lines. The surrounding area is densely forested, with fewer disturbances visible.

Credit: CREDIT_HERE

loop of radar cross-sections from the radar at Salt Lake City, Utah radar (0:02)

loop of radar cross-sections from the radar at Salt Lake City, Utah radar
Text description of the loop of radar cross-sections from the radar at Salt Lake City, Utah radar (0:02)

The loop is a graphical representation of a cross-section of composite reflectivity, typically used in meteorology. The background is mostly black with horizontal and vertical grid lines forming a graph. The vertical axis is labeled in "kft" indicating thousands of feet, and the horizontal axis is marked with distance in nautical miles. The graph shows color-coded areas in shades of blue, green, and some gray, representing varying levels of reflectivity. These colors create few vertical bands mostly between 10 and 35 nautical miles, rising up to around 30 kft. The lower areas have designs with gradients starting from gray and transitioning to blue and green toward the top. Below the graph, there is a color legend indicating different intensity levels ranging from blue (low) to red (high). At the top, there is a toolbar with a bright red button labeled "CLOSE."

Credit: CREDIT_HERE

time lapse of a microburst (0:01)

time lapse of a microburst
Text description of the time lapse of a microburst video (0:01)

The video depicts a wide landscape view with a significant presence of clouds in the sky. A prominent, dense, dark gray cloud formation dominates the upper portion, suggesting an impending storm. Below, a large, rounded rain shaft extends from the cloud to the horizon. The lower horizon shows a strip of silhouetted trees and buildings, with soft, diffuse sunlight peeking through the breaks in the clouds, creating a subtle contrast between the dark clouds and the lighter patches of sky.

Credit: CREDIT_HERE

idealized microburst

Diagram of a microburst's effect with arrows and impact zones overlaid on an aerial landscape.
idealized microburst
Text description of the idealized microburst image.

The image illustrates a diagram of a microburst overlaid on an aerial view of a landscape. The diagram uses arrows and shaded areas to depict the movement and impact of wind caused by a microburst. At the center is a labeled "Splash-down" point from which multiple white arrows radiate outward, indicating the direction of the wind flow. These arrows spread over an elongated, oval-shaped area labeled with "Ground-level Streamlines." The right section of the diagram is bordered with a dashed line marking the "Major Axis of Microburst." To the right of the streamlined area, there's a textured, dotted section labeled as the "Area of damaging ‘straight-line winds.’" The aerial background shows a patchwork of fields and roads.

Credit: David Babb @ Penn State is licensed under CC BY-NC 4.0(opens in a new window)

 

Severe Weather Watches and Warnings

severe weather reports from November 5

Map of the Midwest and Great Lakes regions with colored markers labeled W, T, and H.
severe weather reports from November 5
Text description of the severe weather reports from November 5 image.

The image is a map showing parts of the Midwest and Great Lakes regions, including cities like Chicago, Detroit, and Columbus. Various interstates and highways crisscross the area. There are several markers in different colors and letters: blue "W" markers, red "T" markers, green "H" markers. The markers are scattered across the map, with clusters around northern Ohio, northeastern Indiana, and central Ohio. The map includes notable features like Lake Erie in the northeast.

Credit: CREDIT_HERE

zoomed out look at the severe weather reports from November 5

Map of U.S. showing storm reports from November 5, 2017, with tornado, wind, and hail incidents.
zoomed out look at the severe weather reports from November 5
Text description of the zoomed out look at the severe weather reports from November 5 image.

The image is a map of the United States displaying storm reports for November 5, 2017. The map highlights various locations with symbols indicating different types of storm reports. Red dots represent tornado reports, blue dots indicate high wind reports, and green dots denote hail reports. The majority of the reports are concentrated in the eastern and central parts of the U.S., particularly around the Great Lakes region and stretching southward. In the lower left corner, the logo for NOAA's National Weather Service is present. A legend at the top indicates the color coding for the reports.

Credit: CREDIT_HERE

animation of SPC watches superimposed on radar (0:01)

animation of SPC watches superimposed on radar
Text description of the animation of SPC watches superimposed on radar (0:01)

The animation is a weather map of the contiguous United States. It shows various weather patterns across the country. Green areas indicate precipitation, mainly concentrated in the Pacific Northwest, Upper Midwest, and along the Eastern seaboard. The Central and Southeastern U.S. are marked with multiple colored polygons, indicating severe weather warnings. Red polygons represent tornado watches, stretching from the Mississippi River valley into the Appalachian region. Blue polygons indicate severe thunderstorm watches in parts of the Midwest and Northeast. The map's background is white with state boundaries and major cities outlined in light gray. A blue NOAA logo appears in the bottom left corner.

Credit: CREDIT_HERE

 

Squall Lines, Derechos, and Bow Echoes

visible satellite image of a squall line

Satellite image showing clouds over several U.S. states with outlined borders.
visible satellite image of a squall line
Text description of the visible satellite image of a squall line image.

The image is a satellite view capturing cloud formations over a specific region. The topography of the land is faintly visible beneath extensive cloud cover. Large, dense cloud masses dominate the upper and right portions, showcasing a sweeping pattern from the northwest to the southeast. Smaller, circular cloud formations are evident towards the lower left, appearing as a line of clouds extending diagonally. The borders of several U.S. states are outlined with subtle blue lines for geographical reference.

Credit: CREDIT_HERE

leading to long, nearly continuous thunderstorms

Two-panel diagram. Panel 1 shows storm winds and fronts, Panel 2 shows a curved storm system with color bands.
leading to long, nearly continuous thunderstorms
Text description of the leading to long, nearly continuous thunderstorms image.

The image is divided into two panels labeled '1' and '2.' Panel 1 depicts a diagram with a large pink arrow pointing diagonally upward labeled "Upper-Level Storm-Relative Winds." Below, a blue curved line represents a front, adorned with triangular points facing upward. Small circular patterns with red, yellow, and green sections appear alongside the line. Panel 2 shows a curved, layered band of colors with red at the center, surrounded by yellow and green, indicating a storm system. Both panels feature blue lines along the curved paths, suggesting movement or direction.

Credit: David Babb @ Penn State is licensed under CC BY-NC 4.0(opens in a new window)

creating a broken squall line

Diagrams of weather patterns with arrows and multicolored shapes indicating storm dynamics.
creating a broken squall line
Text description of the creating a broken squall line image.

The image is divided into two sections labeled "1" and "2," featuring diagrams related to atmospheric conditions. In the first section, a blue line with triangular markers indicates a weather front. Four multicolored circles, each with concentric rings of red, yellow, green, and blue, are positioned along the line, suggesting movement or rotation. A large purple arrow labeled "Upper-Level Storm-Relative Winds" points diagonally from left to right, crossing the blue line and circles. The second section retains the blue line with triangles, but now each circle is replaced by an elongated, oval shape with similar concentric colors, aligned along the line.

Credit: David Babb @ Penn State is licensed under CC BY-NC 4.0(opens in a new window)

occasionally is ahead of the squall line or even parallel to it

Diagram of three storm evolution types: Trailing, Leading, and Parallel Stratiform at Initiation, Development, and Maturity stages.
occasionally is ahead of the squall line or even parallel to it
Text description of the occasionally is ahead of the squall line or even parallel to it image.

The image illustrates three stages (Initiation, Development, Maturity) of storm system evolution, depicted in three types: TS (Trailing Stratiform), LS (Leading Stratiform), and PS (Parallel Stratiform). Each type is represented by a series of diagrams, showing progression from left to right. At the Initiation stage, small, elongated storm cells with red cores are highlighted. As the systems develop, these cells cluster into larger formations with green and yellow areas, indicating different intensities or types of precipitation. The Maturity stage shows fully developed storm systems, larger and more complex, with pronounced green and yellow areas surrounding the red cores. Arrows between the stages indicate progression. A scale at the bottom left corner denotes a distance of 100 km.

Credit: CREDIT_HERE

shelf-cloud photo

A green agricultural field under a large gray shelf cloud.
shelf-cloud photo
Text description of the shelf-cloud photo image.

The image displays a vast agricultural field in the foreground, covered in lush green crops. Above the field is a dramatic shelf cloud stretching across the sky, characterized by its smooth, elongated, horizontal shape. The cloud is predominantly gray, with varying shades that give it a layered appearance. To the right, in the background, there are patches of darker clouds, suggesting an impending storm. A few trees are visible towards the horizon, lining the edge of the field. To the left, there is a utility pole with wires extending across the scene, adding a sense of depth.

Credit: CREDIT_HERE

18Z surface analysis

Surface analysis weather map of the U.S. with isobars, fronts, and temperatures from January 29, 2008.
18Z surface analysis
Text description of the 18Z surface analysis image.

The image is a detailed surface analysis weather map of the contiguous United States, dated Tuesday, January 29, 2008. It displays isobars, fronts, and temperature data. Curved red lines represent isobars indicating barometric pressure. Blue and red symbols represent cold and warm fronts, respectively. Numbers with colors signify temperature and weather conditions across different locations. High-pressure zones are denoted by "H" and low-pressure zones by "L." The map features a cold front stretching from the southern tip of Texas to the Midwest, while several pressure lines create tight loops indicating low-pressure centers, especially in the north-central U.S.

Credit: CREDIT_HERE

map of SPC storm reports for January 29, 2008

Map showing storm reports across the U.S. on January 29, 2008, with tornado, wind, and hail reports indicated by red, blue, and green dots.
map of SPC storm reports for January 29, 2008
Text description of the map of SPC storm reports for January 29, 2008 image.

The image is a map of the contiguous United States highlighting severe weather reports from January 29, 2008. Various colored dots, each representing different types of storm reports, are concentrated mainly in the central and eastern parts of the country. Red dots indicate tornado reports, blue dots show wind reports, and green dots represent hail reports. A legend in the bottom left corner details the types and numbers of reports: 4 tornado reports, 276 wind reports, and 29 hail reports. The map is produced by the NOAA/NWS Storm Prediction Center in Norman, Oklahoma. Text at the top provides the date and update time of the data.

Credit: CREDIT_HERE

stream of air to rush into the back edge of the squall line

Diagram showing airflow around a squall line with labeled arrows indicating the Rear inflow jet and Cold Pool.
stream of air to rush into the back edge of the squall line
Text description of the stream of air to rush into the back edge of the squall line image.

The image is an illustrative diagram showing the structure and airflow of a squall line, a type of severe weather phenomenon in meteorology. The background is a gradient transitioning from light blue at the top to darker blue towards the bottom, representing the sky. Large white cumulonimbus clouds dominate the right side of the image, with varying shades indicating depth and volume. Blue arrows, labeled "Rear inflow jet" and "Cold Pool," indicate the direction of the inflow and outflow of air, depicted curving downward and toward the cloud base. A yellow arrow points horizontally across the upper part of the clouds, signifying the direction of the storm’s forward movement. The bottom of the image features a stripe of dark green and brown, representing the ground, with "NW" marked on the left and "SE" on the right, showing the directional orientation.

Credit: David Babb @ Penn State is licensed under CC BY-NC 4.0(opens in a new window)

experience a derecho at least once every few years

Map showing derecho frequency across the U.S. with zones labeled one every year, every two years, every four years, and four every three years.
experience a derecho at least once every few years
Text description of the experience a derecho at least once every few years image.

The image is a map of the continental United States illustrating the climatology of derechos, a specific type of storm event. The map uses shaded regions to indicate the frequency of derechos. The darkest region, centered over parts of the Midwest, shows where one derecho occurs every year. Moving outward, lighter shades represent decreasing frequencies: one derecho every two years, every four years, and four derechos every three years in different parts of the country. Each region is clearly labeled with its respective frequency. The overall color scheme includes shades of green, orange, and purple to distinguish the zones. States are outlined but not labeled individually. The text "Derecho Climatology" is in a bold rectangle at the bottom left corner.

Credit: CREDIT_HERE

ferocious squall lines that display multiple bow echoes on radar imagery

Weather map depicting a low-pressure system, fronts, and a squall line in the central U.S. with colored precipitation bands.
ferocious squall lines that display multiple bow echoes on radar imagery
Text description of the ferocious squall lines that display multiple bow echoes on radar imagery image.

The image is a weather map depicting a meteorological scenario over the central and eastern United States. A red "L" indicates a low-pressure system located in the north-central region. A blue line with triangular markers and a red line with semi-circular markers represent a weather front extending across several states. The map highlights a region with colored bands showing varying levels of precipitation. The colors range from red, indicating heavy rain or hail, to green showing light rain, with a blue outline representing cloud cover. The labels "Derecho (bow echoes on radar)" and "Classic squall line (linear echo on radar)" indicate observed weather phenomena. A legend in the bottom right corner explains the color coding: red for heavy rain/hail, yellow for moderate rain, green for light rain, and grey for cloud outline.

Credit: CREDIT_HERE

radar loop of the June 29, 2012 derecho (0:08)

radar loop of the June 29, 2012 derecho
Text description of the radar loop of the June 29, 2012 derecho (0:08)

The loop is a radar weather map depicting the northeastern United States, highlighting storm systems in various colors indicating intensity. Two major storm formations are visible, one in the Great Lakes region and another spanning from Ohio to the East Coast. The storms are illustrated with colors ranging from green to red, with red indicating the most intense activity. The left storm, over the Great Lakes, is predominantly yellow and red, while the right storm stretches from Ohio to the coastal areas, showing a dense area of yellow and red coloring. Various cities and locations are labeled with white text and green or white circles, indicating weather stations and recorded temperatures, with readings in degrees Fahrenheit near each location. A color scale on the left represents precipitation levels.

Credit: CREDIT_HERE

 

Putting a Spin on Supercells and Tornadoes

F5 tornado funnel cloud Elie Manitoba 2007

A funnel cloud forming under dark storm clouds above a rural landscape with fields and power lines.
F5 tornado funnel cloud Elie Manitoba 2007
Text description of the F5 tornado funnel cloud Elie Manitoba 2007 image.

The image depicts a narrow funnel cloud extending from a dark, swirling storm cloud toward the horizon in a rural landscape. The sky is predominantly covered with thick, dark grey clouds, indicating severe weather. The funnel cloud is slender and reaches toward the ground but does not appear to make contact. Below the stormy sky, a stretch of open field is visible, lush and green, with a row of trees in the distance. On the right side of the image, several wooden utility poles with overhead power lines are seen, stretching into the distance. The overall atmosphere is tense and dramatic, characteristic of an impending tornado.

Credit: By Justin1569 at English Wikipedia, CC BY 2.5, https://commons.wikimedia.org/w/index.php?curid=5943886

flatten entire neighborhoods and grab top headlines

Front page of The Tuscaloosa News featuring tornado destruction with headline - We Unburied Ourselves.
flatten entire neighborhoods and grab top headlines
Text description of the flatten entire neighborhoods and grab top headlines image.

The image is a front page of "The Tuscaloosa News," dated Friday, April 29, 2011. The main headline reads "'We Unburied Ourselves'." Below this is an aerial photograph showing a devastated landscape with debris and destroyed buildings, indicating widespread damage. The damage appears concentrated near an intersection, possibly the result of a tornado. To the left of the main image is a sidebar with two small profile photos of people and text detailing assistance information. Below the main image is another headline: "37 confirmed dead; 800 injured." A small inset map shows the path of the tornado on April 27, 2011, highlighting the affected areas. The bottom of the page includes a group photo of people including Gov. Robert Bentley, shown on a site visit.

Credit: Tuscaloosa News April 29, 2011

world map from the National Climatic Data Center

World map highlighting countries in light orange on the Robinson Projection, including Canada, the USA, several European and Asian nations, Australia, and South Africa.
world map from the National Climatic Data Center
Text description of the world map from the National Climatic Data Center image.

The image is a world map using the Robinson Projection, depicting countries in light orange and white. Countries highlighted in light orange include Canada, the United States, various countries in Europe, Turkey, parts of the Middle East, Japan, South Korea, several countries in Southeast Asia, Australia, New Zealand, and South Africa. Major oceans are labeled in blue, and the map includes geographic markers such as the equator and tropic lines. The countries are outlined clearly, and major cities are labeled within each.

Credit: CREDIT_HERE

Tornado Alley

Map highlighting Tornado Alley in brown, covering parts of central U.S. states.
Tornado Alley
Text description of the Tornado Alley image.

The image is a map of the United States with a focus on the central region, highlighting an area labeled as "Tornado Alley." The map is colored in shades of green, with state borders marked but not labeled. A central brown area covers parts of several states, indicating the region known for frequent tornadoes. The highlighted area roughly encompasses parts of Texas, Oklahoma, Kansas, Nebraska, and South Dakota. The text “Tornado Alley” is prominently displayed in red at the lower left of the highlighted area.

Credit: David Babb @ Penn State is licensed under CC BY-NC 4.0(opens in a new window)

animation showing the probability of a tornado on select dates throughout the year (0:06)

animation showing the probability of a tornado on select dates throughout the year
Text description of the animation showing the probability of a tornado on select dates throughout the year (0:06)

The animation is a heat map of the United States illustrating tornado probabilities on June 17th, aggregated over the years 1982 to 2011. The map uses varying shades of orange and red to depict probability levels, with darker shades indicating higher probabilities. The central region of the United States, especially areas covering parts of Nebraska, Kansas, Missouri, Iowa, and Illinois, is shaded in dark red, denoting the highest likelihood of tornado occurrence. Lighter shades extend outwards from this core region, covering much of the Midwest and reaching into parts of the South and East. The background of the map shows state boundaries for context. A legend at the bottom indicates the probability range from 0.10% to 14.0% or more. The NOAA and Storm Prediction Center logos are displayed in the bottom left corner.

Credit: CREDIT_HERE

peak of tornado activity occurring in May, on average

Line graph showing average monthly tornado frequency in the contiguous U.S. from 1991-2015, peaking in May.
peak of tornado activity occurring in May, on average
Text description of the peak of tornado activity occurring in May, on average image.

The image displays a line graph titled "Tornado Average by Month in the Contiguous United States." The data covers the years from 1991 to 2015. The horizontal axis represents the months of the year from January to December, while the vertical axis shows the number of tornadoes ranging from 0 to 300. The line graph is plotted with blue lines connected by diamond-shaped points. The graph shows that tornado occurrences are lowest in January and February with 36 and 32 tornadoes respectively, increase steadily through March (75) and April (178), peaking sharply in May at 269 tornadoes. The numbers decrease through June (229), July (123), and continue to drop gradually through December with 27 tornadoes. Each peak and significant change in the data is labeled with corresponding numbers in brown.

Tornado Average by Month in the Contiguous United States 1991-2015.
Jan 36, Feb 32, Mar 75, Apr 178, May 269, Jun 229, Jul 123, Aug 75, Sep 66, Oct 58, Nov 56, Dec 27.

impart spin on a horizontal "noodle" of air

A pink horizontal cylinder with yellow spiral arrows on a blue background.
impart spin on a horizontal "noodle" of air
Text description of the impart spin on a horizontal "noodle" of air image.

The image shows a horizontal cylinder in the center, colored in a gradient of pink hues, placed against a light blue background. The cylinder has a subtle 3D effect giving it a rounded appearance. Surrounding the cylinder are several yellow curved arrows evenly spaced along its length. These arrows are evenly oriented, showing a downward spiral motion around the cylinder. At the bottom of the image, there is a horizontal strip that transitions from green to brown, resembling a ground or base.

Credit: David Babb @ Penn State is licensed under CC BY-NC 4.0(opens in a new window)

conservation of angular momentum (0:12)

conservation of angular momentum
Text description of the conservation of angular momentum video (0:12)

The video depicts a three-dimensional, grey cylinder positioned centrally on a green grid plane. The grid extends into the background, creating a sense of perspective. Two large, red arrows flank the cylinder on either side, pointing inward towards it. The background above the grid features a gradient from light purple at the top to white, enhancing the depth of the scene. The shadow of the cylinder is visible on the grid below, indicating a light source positioned above. The image is likely meant to illustrate the concept of convergence and angular momentum. The image then morphs to where the arrows point outward illustrating divergence.

Credit: CREDIT_HERE

 

More on Supercells and Tornadoes

classic supercell displays a hook echo on images of radar reflectivity

Color-coded topographical map showing rain intensity, with a mesocyclone labeled.
classic supercell displays a hook echo on images of radar reflectivity
Text description of the classic supercell displays a hook echo on images of radar reflectivity image.

The image illustrates a color-coded topographical map indicating varying levels of rain intensity. The map uses concentric shapes, with the innermost area shaded red, labeled as "Heavy Rain (and Hail)." Surrounding this is an orange area, followed by yellow, green, and finally, light blue, which represents "Light Rain." In the lower left corner, there is a label "Mesocyclone" with a red dashed circle and a capital letter "T" inside it, indicating the presence of a mesocyclone, often associated with severe weather. In the upper right, a purple arrow labeled "Movement" points to the right, showing the direction of movement.

Credit: David Babb @ Penn State is licensed under CC BY-NC 4.0(opens in a new window)

highest reflectivity is displaced from the updraft and mesocyclone

Color-coded topographical map showing rain intensity, with a mesocyclone labeled.
highest reflectivity is displaced from the updraft and mesocyclone
Text description of the highest reflectivity is displaced from the updraft and mesocyclone image.

The image illustrates a color-coded topographical map indicating varying levels of rain intensity. The map uses concentric shapes, with the innermost area shaded red, labeled as "Heavy Rain (and Hail)." Surrounding this is an orange area, followed by yellow, green, and finally, light blue, which represents "Light Rain." In the lower left corner, there is a label "Mesocyclone" with a red dashed circle and a capital letter "T" inside it, indicating the presence of a mesocyclone, often associated with severe weather. In the upper right, a purple arrow labeled "Movement" points to the right, showing the direction of movement.

Credit: David Babb @ Penn State is licensed under CC BY-NC 4.0(opens in a new window)

radar cross-section of a supercell

3D visualization of precipitation in a storm, showing rear and forward-flank precipitation with color-coded intensity levels.
radar cross-section of a supercell
Text description of the radar cross-section of a supercell image.

The image is a 3D visualization of precipitation within a storm, showing cross-sectional data with layered contours. The colors represent different precipitation intensities, ranging from light blue to pink. On the left side, labeled "Rear-Flank Precipitation," there are layers of blue and green transitioning to yellow and red, indicating increasing intensity. On the right side, "Forward-Flank Precipitation" is depicted, with similar color transitions extending to the edge of the section. Pink areas in the center indicate the highest precipitation intensity. The visualization includes labels with white lines pointing towards the rear and forward flank regions, set against a dark background with a horizontal plane at the bottom.

Credit: CREDIT_HERE

wall cloud

Dark storm cloud with a lightning bolt striking the ground, and a hint of sunlight in the distance.
wall cloud
Text description of the wall cloud image.

The image showcases a dramatic weather scene with a dark, ominous storm cloud dominating the sky. The cloud is large and billowy, featuring varying shades of gray, with the top of the cloud extending into the upper part of the image. Beneath the storm cloud, a bright lightning bolt strikes diagonally from the middle right towards the ground, providing a stark contrast against the darker background. In the distant left, a faint, warm glow from the setting or rising sun adds a splash of yellow and orange hues. The horizon is flat and dark, indicating a wide, open landscape beneath the tumultuous sky.

Credit: NOAA Photo Library

classic hook echo

Radar image showing a
classic hook echo
Text description of the classic hook echo image.

The image is a radar map showing precipitation patterns. The primary focus is a distinct weather formation known as a "hook echo," displayed in the upper right quadrant, highlighted by a white circle and arrow. This formation resembles a hook, indicating potential tornado activity. The radar imagery includes a color gradient scale from blue to red, representing increasing precipitation intensity. The lower left corner shows a radial pattern surrounding a central point, marked "KUEX," depicting radar station location. Other weather cells are present in the upper left with predominantly green, yellow, and blue colors.

Credit: CREDIT_HERE

 

Tornado Damage, Safety, and Myths

Minor

A red brick building with a shingle roof and a Reserved Parking sign for disabilities in the foreground.
Minor
Text description of the Minor image.

The image depicts the exterior of a single-story building constructed from red brick. The roof is dark brown and made of shingles, with a visible patch in the center that appears to be discolored or damaged. The building has small, rectangular windows partially visible along the side. In front of the building is a well-maintained lawn with a few small shrubs near the base of the wall. A sign in the foreground designates a "Reserved Parking" spot for individuals with disabilities. The sky is clear and blue, with part of a large tree visible in the distance on the right side.

Credit: National Weather Service

Moderate

Damaged suburban house with collapsed roof and bent garage door.
Moderate
Text description of the Moderate image.

The image shows a suburban brick house with a damaged roof. Large sections of the roof have collapsed, exposing wooden beams and debris. The house has two visible windows on the left side, both of which remain intact. In front of the house is a neatly maintained lawn with a brick mailbox near the street. A cracked driveway leads to the garage, whose door appears to be bent and partially detached. A dark-colored car is parked on the driveway to the right of the image. The sky above is partly cloudy with bright sunlight illuminating the scene.

Credit: National Weather Service

Considerable

A damaged brick house with exposed roof beams, a parked sedan, and a blue dumpster nearby.
Considerable
Text description of the Considerable image.

The image depicts a single-story brick house with extensive roof damage, exposing the wooden framework. Several wooden beams protrude upwards from the roof, indicating recent destruction. Two large windows with shutters flank the entrance, which has steps leading to a door that is ajar, showing some debris at the entrance. A grey sedan is parked on the driveway in front of the house. To the right, two men stand near a large blue dumpster placed next to the garage. Above the garage, a decorative metal star is fixed on the wall. Lush green grass covers the foreground, while large trees with full foliage are visible on either side, framing the house. The sky is overcast with scattered clouds.

Credit: National Weather Service

Severe

A heavily damaged house with debris, a man inspecting the ruins, and yellow caution tape.
Severe
Text description of the Severe image.

The image shows a scene of significant destruction, likely caused by a natural disaster. In the foreground, a house appears severely damaged, with its walls partially collapsed and debris scattered on the ground. A man is inspecting the wreckage, leaning over some of the fallen structure. The remnants of walls show various colored doors, including a red one, still upright. Bushes and a small tree are visible near the wreckage, slightly obscuring part of it. Yellow caution tape is stretched across the area, indicating restricted access. In the background, overcast skies cover the area, adding a somber tone to the scene.

Credit: National Weather Service

Devastating

Debris and destruction from a natural disaster, with broken trees and scattered household items, including an American flag among the wreckage.
Devastating
Text description of the Devastating image.

The image shows a scene of extensive destruction likely caused by a natural disaster. The foreground is dominated by debris, including broken bricks, wooden planks, household items, and trees. Large tree trunks lie on the ground, splintered and uprooted. In the middle ground, more debris is scattered, including household items such as furniture and clothing, amidst wrecked structural components. Towards the background, a few trees remain standing, albeit damaged, with their branches stripped and broken. An American flag is visible among the debris, adding a poignant element to the scene. The overall color palette is earthy with browns and greens, contrasting with white and red from the debris.

Credit: National Weather Service

Incredible

Debris scattered around a concrete foundation in an open, grassy area with an overcast sky.
Incredible
Text description of the Incredible image.

The image shows the aftermath of a destructive event, likely a tornado, in an open area. A concrete foundation is visible in the foreground, where a structure once stood, now surrounded by scattered debris. Items such as a red gas cylinder, white tanks, wooden planks, and various building materials are strewn across the area. The background reveals a flat, grassy field with sparse trees and scattered debris extending into the distance. The sky above is overcast with a hint of blue, suggesting a recent storm.

Credit: National Weather Service

locations are plotted on this map

Map of U.S. showing F5/EF5 tornado locations from 1950 to present with numbered markings.
locations are plotted on this map
Text description of the locations are plotted on this map image.

The image is a map of the central and eastern United States, indicating the locations of F5/EF5 tornadoes from 1950 to the present. The states are outlined in black, and the map highlights specific states where tornadoes have occurred. Blue numbers are scattered across the map within state boundaries, each representing a specific tornado occurrence. The numbers are distributed across states such as Texas, Oklahoma, Kansas, Missouri, and several others in the Midwest and Southeast. The background is plain, providing clear visibility of the map and numbers.

Credit: CREDIT_HERE

graph of tornado fatalities in the U.S. from 1940 through 2011

Bar chart depicting tornado fatalities in the U.S. from 1950 to 2011.
graph of tornado fatalities in the U.S. from 1940 through 2011
Text description and data table for the graph of tornado fatalities in the U.S. from 1940 through 2011 image.

The image is a bar chart illustrating tornado fatalities in the United States from 1950 to 2011. The horizontal axis represents the years, marked from 1950 to 2011, while the vertical axis shows the number of fatalities, ranging from 0 to 600. Each bar corresponds to a particular year and indicates the number of deaths caused by tornadoes in that year. Noticeable peaks appear in 1953, 1974, and 2011, with 2011 showing the highest number of fatalities, reaching close to 600. There are several smaller peaks throughout the chart, but most years have relatively low fatalities.

U.S. Tornado Fatalities by Year (1950–2011)
YearFatalities
195070
195134
1952231
1953519
195436
1955129
195683
1957193
195867
195958
196046
196152
196230
196331
196473
1965301
196698
1967114
1968131
196966
197073
1971159
197234
197389
1974366
197560
197644
197743
197853
197984
198028
198124
198264
198334
1984122
198594
198615
198759
198832
198950
199053
199139
199239
199356
199448
199534
199626
199768
1998130
199994
200041
200140
200255
200354
200435
200538
200667
200781
2008128
200921
201045
2011553
Credit: NOAA Storm Events Database

Full-size image

Aerial view of a grassy field with a cycloid pattern highlighted by white lines.
Full-size image
Text description of the Full-size image image.

The image is an aerial view of a grassy field showcasing a faint cycloid pattern. The grass is predominantly green with various shades and patches scattered throughout. There are multiple circular arcs forming a repetitive, wavy line across the field, which denotes a cycloid pattern. Several brown and reddish streaks can be seen on the right, possibly indicating paths or disturbed soil. Two white lines intersect at the pattern, highlighting it, with text positioned below.

Credit: CREDIT_HERE

tracked for miles across the mountainous northwest and north-central parts of the state

Map showing the May 31, 1985, tornado outbreak paths in Ohio and Pennsylvania with a topographic map on the right.
tracked for miles across the mountainous northwest and north-central parts of the state
Text description of the tracked for miles across the mountainous northwest and north-central parts of the state image.

The image is a split-view map detailing the May 31, 1985, tornado outbreak. On the left, there is a map labeled with different colored lines indicating tornado paths across portions of Ohio and Pennsylvania. A color-coded legend shows tornado intensity (F-Rating), ranging from yellow (0) to dark red (5). The National Weather Service logo is in the top left corner. On the right, a topographic map of the same region shows variations in elevation with colors ranging from green to brown, accompanied by blue boundary lines and grid labels for latitude and longitude.

Credit: CREDIT_HERE

 

Other Whirlwinds

the edges of such boundaries can be areas ripe for creating low-level spin

Diagram showing airflow and spin development in a heated region with caption below.
the edges of such boundaries can be areas ripe for creating low-level spin
Text description of the the edges of such boundaries can be areas ripe for creating low-level spin image.

The image is a diagram illustrating air movement and the development of spin in a heated region. The background is black, featuring horizontal white arrows moving from left to right, representing airflow. In the center, an oval-shaped "Heated Region" is outlined in yellow with diagonal lines extending within it, indicating warmth. A dashed yellow line curves along the right side of the oval, illustrating the path where convergence and spin develop. The airflow diverges slightly upon entering and exiting the heated region. The diagram is captioned below.

Credit: CREDIT_HERE

visually stunning

A waterspout stretches from a cloud to the ocean surface, with swirling water below.
visually stunning
Text description of the visually stunning image.

The image depicts a waterspout over the ocean. A distinct vertical funnel extends from a dark cloud above to the surface of the water, creating a dramatic scene. The waterspout is centered in the frame, with the sea appearing turbulent where the funnel meets the water. The colors in the image are predominantly blue, with variations in intensity, displaying the contrast between the ocean surface and the surrounding sky. The cloud cover is dense, casting shadows over parts of the water, enhancing the contrast with the lighter areas of the sky.

Credit: NOAA Library

map showing the average number of tornado days per year from 2003 - 2012

Map showing tornado days per year across the U.S. from 2003-2012, with colors indicating frequency.
map showing the average number of tornado days per year from 2003 - 2012
Text description of the map showing the average number of tornado days per year from 2003 - 2012.

The image is a map of the continental United States displaying tornado days per year based on reports from 2003 to 2012. The map is color-coded with areas shaded in various hues of yellow, orange, and red, indicating the frequency of tornado days, ranging from 1 to over 6 days per year. The Midwest and Southeast regions are predominantly highlighted, with darker shades indicating higher frequencies, particularly in parts of Alabama and Mississippi. States are outlined in black, and major geographic regions are discernible. The map includes a legend on the right with a gradient scale from yellow to red, labeled "Days per year." To the bottom left, there is a logo for the NOAA National Weather Service Storm Prediction Center.

Credit: CREDIT_HERE

kick up dust in open areas

Dark storm clouds with a dust cloud rising on the horizon, power lines crossing the scene.
kick up dust in open areas
Text description of the kick up dust in open areas image.

The image shows a dark, stormy scene with prominent cloud cover occupying the upper portion of the frame, casting a gloomy atmosphere. Below, a dust cloud is rising above the horizon, suggesting strong winds or a possible tornado forming in the distance. The landscape beneath the clouds is flat and appears rural, with some grass visible in the foreground. There are power lines running diagonally across the image, and a few dimly lit buildings can be seen near the horizon, adding to the desolate feel of the scene.

Credit: Rick McCoy via the National Weather Service