Mounds of hail resembling rocks line the ditch as shown in this photograph taken on the afternoon of Wednesday, April 11, 2012 in Potter County, TX

Meteorologists from the Amarillow National Weather Service office compiled several photographs from the public and also conducted a storm survey in northern Potter County along U.S. highway 287 24 hours after the storm to assess the full impact.  Their findings were quite dramatic.

The hail piled into 3-4-foot tall drifts on both sides of U.S. Highway 287, forcing a closure of the highway for more than 12 hours on Wednesday, April 11, 2012.

A slow-moving severe thunderstorm just south of the town of Masterson brought not only heavy hail, but also very heavy rain.  The rain acted to float the hail across the surface, resulting in large “drifts” of hail piling up in ditches and against roadway culverts.

A traffic camera shows the backup caused by the drifts of hail that forced cars off the road, bringing traffic to a halt on Wednesday, April 11, 2012 in Potter Co. Texas

Radar estimates indicate 5 to 6 inches if rain fell in an area about 25 miles north of Amarillo, all inside of a 1-2 hour period.  Hail to the size of golfballs fell and the runoff from the heavy rain created 3-4 foot drifts across U.S. Highway 287.  The hail forced the roadway to be shut down for over 12 hours.

Traffic was brought to a standstill by the April 11th storm in Potter Co. Texas.

When National Weather Service meteorologists surveyed the area on Thursday — nearly 24 hours after the storm — they still found mounds of hail that had not yet melted lining the sides of the roadway.

Hail several inches deep still lined the roadway nearly 24 hours after the storm when meteorologists surveyed the scene on Thursday, April 12, 2012.

Semi tractor trailers sail through the air like toys as a tornado touches down in Dallas County, Texas on April 3, 2012. For video, scroll down.

Tornadoes were also reported in the cities of Arlington and Lancaster, Texas.  News footage showing tractor-trailers being thrown about like toys by the massive tornado filled the airwaves on Tuesday, capturing headlines across the country.

Damage resulting from the tornado outbreak of April 3, 2012 in the Dallas-Fort Worth area.

Several dozen homes in the path of the tornadoes were also damaged or destroyed.  Tens of thousands of residents are still without power and hundreds of flights have been canceled at DFW airport while officials assess hail and wind damage to planes that were exposed to the storms.

Dallas-Forth Worth television station WFAA captured incredible footage of one of the tornadoes from their news chopper that reported live as the events unfolded.

As of 6:00pm on Tuesday evening, the Storm Prediction Center had received at least a dozen reports of tornadoes across the state, most centered on the Dallas-Forth Worth area.  That number may fluctuate as the National Weather Service investigates the reports in the coming days.

Damage resulting from the tornado outbreak centered on Dallas-Fort Worth Texas on April 3, 2012.

However, upon preliminary review, the National Weather Service has confirmed that “considerable damage” was reported near Cleburn, south of Fort Worth, and in the city of Lancaster.

Cloud Streets shown just west of Kansas City on the morning of March 7, 2012.

A spectacular, though fleeting, display of low-level cloud streets were visible over the Kansas City metro area Wednesday morning as strong low- and mid-level southerly flow usured in moisture from the south. 

Cloud streets generally orient themselves parallel to the low-level flow, with a slight slant of 10-20 degrees to the left.  This orientation was evident this morning as strong southerly flow created streets that were generally oriented from the south-southwest to the north-northeast. 

Cloud Streets shown just west of Kansas City on the morning of March 7, 2012.

Cloud streets generally form within the lowest mile or so of the atmosphere – a region known as the planteary boundary layer.  This is the area where upper-level winds and low-level winds mix and great interesting phenonmenon when conditions are suitable. 

Cloud Streets shown just west of Kansas City on the morning of March 7, 2012.

In the case of cloud streets, winds that are relatively constant speeds with height will create favorable conditions.  Though wind speeds are generally constant, multiple sources of thermal currents from below will give rise to a series of rolls that become visible when moisture condenses into clouds. 

Cloud Streets shown just west of Kansas City on the morning of March 7, 2012.

This effect is strengthened when a low-level temperature inversion is in place — that is, when temperatures at lower levels are cooler than temperatures at higher levels.  The inversion acts as a ‘cap’ on the atmosphere, preventing further upward motion, as colder air is less buoyant than warmer air.  This turns the rising thermals around, generating the ‘rolling’ motion necessary to create the clean edges seen in the cloud streets. 

In the case of the Kansas City display today, the steets were not visible from visible satellite imagery, as higher-level clouds covered the low-level streets, though cloud streets have been visible in satellite photographs in the past when upper-level clouds aren’t present. 

Visible Satellite Imagery showing the Southern Plains of the United States the morning of March 7, 2012.

Satellite Imagery of Hurricane Irene at its highest intensity: Category 3 several days before making landfall on the Outer Banks of North Carolina.

Models indicate the maximum storm surge along the ocean-facing side of the barrier islands from Cape Lookout to Cape Hatteras was roughly 2 m (or approximately 6 feet).  Additionally, 7-meter wave heights observed on the open coast contributed to both erosion of some areas of coastline as well as build-up (deposition of sand) in other areas.

Aerial photographs showing several areas of the Outer Banks both before and after Hurricane Irene demonstrate the destructive force of the storm surge and catastrophic wave motions that resulted from the storm.

Location 1: Vertical aerial photographs of Core Banks, NC, from June 12, 2010 and August 28, 2011; one day after landfall of Hurricane Irene. The red line in the lower photo is the location of the oceanfront shore on June 12, 2010. This location is 30-35 km northeast of landfall and in the hurricane's right-front quadrant. A breach has been cut through the barrier island. This is not an unusual occurrence at this location; inlets have been observed here in other photography. Such inlets close naturally by infilling with sand over weeks and months, then reopen during storms like Irene.

Location 2: Oblique aerial photographs of Ocracoke Island, NC, from May 6, 2008 (top, pre-storm) and August 30, 2011 (bottom, post-storm, acquired three days after landfall of Hurricane Irene). The yellow arrow in each image points to the same feature. Overwash deposits of sand extend over the road after the storm. Heavy equipment is at work clearing the road, which appears buried rather than destroyed. Overwash extended tens of meters landward of the road into the marsh grasses on the sound-side of the island.

Location 3: Oblique aerial photographs of Hatteras Village, NC, from May 6, 2008 (top, pre-storm) and August 30, 2011(bottom, post-storm, acquired three days after landfall of Hurricane Irene). The yellow arrow in each image points to the same cottage. Note that the dunes seaward of the cottages may have steepened by wave impacts (the collision regime), but it is not clear with this data. Our lidar results will confirm whether dune erosion occurred. Cottages here appear not to have been significantly impacted by waves and surge.

Location 4: Oblique aerial photographs of Rodanthe, NC, from May 6, 2008 (top, pre-storm) and August 30, 2011 (bottom, post-storm, acquired three days after landfall of Hurricane Irene). The yellow arrow in each image points to the same cottage. A breach was carved through the barrier island, severing NC Highway 12. The storm surge was approximately 2 m high on the sound-side and was less on the ocean-side. Flow from the sound to the ocean may have played a role in cutting the breaches between Oregon Inlet and Cape Hatteras.

Location 5: (Upper image) Oblique aerial photograph of Pea Island National Wildlife Refuge, NC, looking north along the coast on August 30, 2011, three days after landfall of Hurricane Irene. Oblique aerial photos of the central part of upper image from May 6, 2008 (middle, pre-storm) and August 30, 2011 (lower, post-storm). The yellow arrow in each image of the lower images points to the same structure. At this location, two breaches were carved through the island, severing NC Highway 12. With the storm surge higher on the island's sound-side, currents flowing from sound to ocean may have contributed to creating these breaches.

A dust storm approaches Phoenix, Arizona on July 5, 2011. Credit: Bryan Snider

Such strong dust storms — sometimes referred to as a haboob – is a visually-impressive weather phenomena that is common in arid regions such as the desert Southwest.  Dust storms frequently begin when a gust front or other strong wind loosens sand and dust from the Earth’s surface.  The particles are transported by the strong winds and are scraped along the ground, loosening more particles.

A dust storm approaches Phoenix, Arizona on July 5, 2011. Credit: Peter Busch

A dust storm approaches Phoenix, Arizona on July 5, 2011. Credit: Thomas Ballantyne

This dust storm was the result of a long-standing drought in the region that has been compounded by recent record heat.  As the heat builds and less precipitation falls, the ground dries out and a feedback cycle exacerbates the conditions over time.  When the summer monsoon winds build over the dry air, they dislodge the lose particles of dust and sand from the ground.

A dust storm approaches Phoenix, Arizona on July 5, 2011. Credit: M. Moulton

As these particles begin to shift and skip across the ground, they dislodge more particles and the smallest particles begin to remain suspended in the air.  The situation compounds over time, creating blankets of dust sometimes hundreds of feet thick.  This still image captured from the video of a local media reveals the depth of the storm as well as the magnitude, as shown against the backdrop of downtown Phoenix.

A dust storm approaches downtown Phoenix, Arizona on July 5, 2011. Credit: Raphael Torres

A stunning dust storm approaches downtown Phoenix, Arizona on the evening of July 5, 2011.

Even the interior of Sky Harbor Airport was not immune to the fine dust particles that seemed to infiltrate any open door, window, or gap in buildings in the region.

Reduced visibility at Sky Harbor Airport in Phoenix was not only a problem for aircraft, but even for passengers taking refuge in the terminals. July 5, 2011.

While weather radar is traditionally used to detect precipitation, it has also been used to detect many other phenomena.  Now we can add dust storms to the list.  Imagery from the evening revealed the sheer volume of dust elevated into the atmosphere, rising thousands of feet — perhaps as high as a mile — into the sky.  As the dust drifted over Phoenix from the south-southwest, the radar station based in Phoenix was able to detect it.

This animation reveals the extent of the dust storm as it approached downtown Phoenix, Arizona on July 5, 2011.

Radar scans of the atmosphere around Phoenix, AZ on the evening of July 5, 2011 reveal the volume of dust elevated into the atmosphere, rising thousands of feet into the sky.

A visible satellite image of the region reveals widespread thunderstorms blossoming throughout the region.  While the thunderstorms provided hope for widespread rain, many of the storms were relatively dry:  the rain that fell from the bases of the storms often failed to reach the ground, providing instead only the strong outflow of air that resulted in the dust storm that blanketed Phoenix.  However, some areas reported brief downpours following the dust storm, resulting in wet layers of mud coating all outdoor surfaces.

A visible satellite image reveals the widespread thunderstorm activity blossoming over the Southwest on July 5, 2011 that served as the source of gust fronts that kicked up dust, creating the ensuing dust storm. Credit: NOAA

Undulatus Asperatus as seen over Chicago, Illinois on July 1, 2011. Credit: Diana Kost

A dramatic display of a relatively rare cloud type blanketed the city of Chicago on Friday afternoon, drawing the attention of millions of residents.

Undulatus Asperatus as seen over Chicago, Illinois on July 1, 2011. Credit: Jough Dempsey

The clouds are frequently described as how the surface of a body of water looks from the viewpoint of a swimmer beneath the surface. These clouds have recently been deemed undulatus asperatus by meteorologists.  The Latin term translates loosely as “turbulent undulation.”.

Undulatus Asperatus as seen over Chicago, Illinois on July 1, 2011. Credit: Lynn Reidl

Though the appearance of such turubulence frequently invokes concern that a severe storm may be approaching, these clouds actually appear to indicate the opposite: a decaying or otherwise dissipating thunderstorm complex. As shown on the satellite photograph below, a large thunderstorm complex had formed over southern Lake Michigan and was then dissipating and moving away from Chicago at the time these clouds were spotted.

Visible satellite image showing a decaying thunderstorm complex east of Chicago on July 1, 2011.

The automated weather station at the Wichita airport registered a jump from 85 degrees to 102 degrees in a span of just 20 minutes, according to Stephanie Dunten, a meteorologist with the National Weather Service in Wichita.

The surge in temperatures began at 11:22 p.m. CST (12:22am CDT) when a pocket of air in the upper atmosphere collapsed to the surface, Dunten said. That sent winds of more than 50 miles an hour through portions of the city as the air hit the ground and spread out.  According to KAKE-TV, Sedgwick County 911 dispatchers received calls of trees and power lines down. The wind gust set off several alarm systems in the city.  Additionally, a middle school in the city lost most of the roof over its auditorium.

At one point, Westar reported more than 4,000 customers in the Wichita area without power.

The dynamics of a heat burst are surprisingly basic, though they aren’t observed very frequently – perhaps in part because their impacts are not widely felt: they traditionally strike a relatively small area. Heat bursts generally originate from a collapsing thunderstorm. As rain falls through the atmosphere at high elevations, it cools the air beneath it as it evaporates into the air. When this air cools dramatically, it becomes much more dense than the surrounding air, losing its buoyancy. This air then begins plummeting to the surface. As the air descends through the atmosphere, it encounters greater atmospheric pressure. This increase in pressure compresses the air molecules quickly, resulting in a spike in the temperature.

The crashing of the air to the surface also results in a dramatic increase in observed wind speeds as the air spreads out in all directions from the point at which it hit the ground.

As a result, the automated station at the airport registered a high temperature of 102 degrees at 11:42 p.m. CST.

Two years ago, a similarly dramatic heat burst struck Oklahoma City, resulting in temperatures spiking to 90 degrees after midnight on May 13, 2009.  Wind speeds topped 55 mph, resulting in widespread damage was widespread with small trees and limbs reported down throughout the city.

Heat bursts have been observed in other Plains states in recent years.   Kearney, Nebraska was impacted by a heat burst in on June 20, 2006 when the temperature went from 70 to 93 in minutes overnight and wind speeds topped 60 miles per hour.

More recently, on August 3rd, 2008, a heat burst in Sioux Falls, SD forced air downward in such a dramatic fasion that the wind speeds over 50 miles per hour and the temperature jumped from 70 to 101 in less than 20 minutes.

Photographers on the ground have captured similarly-stunning photographs, including Aaron Fuhrman.   He shared several on-the-ground photographs which he shared with NPR, who then combined these photos with screen grabs from Google street view, resulting in the interactive images below.

Click and drag the slider left and right to reveal the impact the EF-5 tornado had on the region.

Grand Avenue:

East 24th Street:

East 24th Street and South Pennsylvania Avenue:

Satellite Photographs over Joplin High School:

Source:  NPR.org

Fires burn in the distance as recue workers navigate decimated neighborhoods within minutes of the EF-5 torndao ravaging Joplin, Missouri on May 22nd, 2011. Credit: AP/Mark Schiefelbein

St. John's Regional Medical Center - a landmark in Joplin, Missouri - sits in the background behind homes and trees decimated by the tornado of May 22, 2011. Credit: AP/Charlie Riedel

Hundreds of windows were blown out of St. John's Regional Medical Center when the EF-5 tornado struck Joplin, Missouri on May 22, 2011. Credit: AP/Tulsa World - Adam Wisneski

The medevac helicopter lies in ruins beside St. John's Regional Medical Center following a direct hit by an EF-5 tornado on Joplin, Missouri May 22, 2011. Credit: AP/Mark Schiefelbein

Automobiles were tossed around like toys by winds topping 200 miles per hour when a devastating EF-5 tornado struck Joplin, Missouri on May 22, 2011. Credit: AP/Mark Schiefelbein

Wooden-frame homes were no match to the 200-mile per hour winds of the EF-5 tornado that struck Joplin, Missouri on May 22, 2011. Credit: Reuters/Mike Stone

A victim of the devastating tornado lies covered in a crushed vehicle following the EF-5 tornado that struck Joplin, Missouri on May 22, 2011. Credit: AP/Charlie Riedel

For ways to help the victims of this devastating storm, visit the Red Cross.  The Red Cross is funded entirely through donations. The organization is asking people who want to help to text REDCROSS to 90999 to make a $10 donation, or you can donate any amount at RedCross.org.