June 29, 2012 Derecho
View from space
POES AVHRR visible, IR, and lightning
On June 29, 2012, a devastating line of severe thunderstorms known as a derecho (deh-REY-cho) moved east-southeast at 60 mph from Indiana in the early afternoon to the Mid-Atlantic region around midnight. The states with the most significant damage included Indiana, Ohio, Kentucky, Pennsylvania, West Virginia, Maryland, Virginia, Delaware, New Jersey and North Carolina, as well as Washington, D.C.
Radar evolution
Winds associated with the derecho were commonly above 60 mph with numerous reports of winds exceeding 80 mph. Some areas reported isolated pockets of winds greater than 100 mph. An unofficial wind gust of 117 mph was reported from a wind turbine in Putnam county Ohio. The derecho resulted in 13 deaths, mainly from falling trees.
Before and after Satellite View
More than 4 million customers lost power, some for more than a week after the derecho moved through, during a record setting heatwave. An additional 34 heat-related fatalities followed in areas without power.
Derecho Facts
Definition
A widespread, long-lived wind storm.
- At least 400 miles long
- At least 60 miles wide
- Wind gusts of 58 mph or greater for most of its length
- Several 75+ mph wind gusts in separate locations
Where Do They Occur?
Derechos occur most commonly from the Central Plains into the Great Lakes Region.
Most Common in May through July
Derechos have occurred in all 12 months, but 63% of all derechos occur in the heart of severe weather season (May-July).
Derecho Types
Serial
- Common in Spring and Fall
- Multiple Bow Echoes in one line
- Covers a very large area (both wide and long)
- Commonly associated with a strong mid-latitude cyclone
Progressive
- Relatively narrow path
- Usually associated with weak weather systems
- Commonly occur during heat-waves.
Learn more about derechos here
Meteorology
Mid-Levels
A strong, but broad, mid-level trough was in place across the CONUS on the morning of June 29, 2012. A shortwave moving from Ontario to Quebec tightened the height gradient and led to seasonably strong mid-level flow across the Great Lakes.
Low Levels
At 850mb, a very moist airmass was in place with dewpoints in the low 20s Celsius from northern Illinois to southern Ohio.
Surface
At the surface, a stationary front was in place from southern Iowa to central Pennsylvania. South of the front, a very warm airmass was in place with temperatures in the upper 70s to low 80s at sunrise.
Mid-Day Surface
By mid-day, temperatures had warmed into the 95-105F range and dewpoints had increased into the low to mid 70s. This yielded extreme instability south of the front. In addition, a local high pressure center can already be seen across northwest Indiana in association with a developing cold pool.
Mid-Day Weather Balloon
The NWS office in Wilmington, Ohio put up a special weather balloon launch at 18Z as the developing derecho was approaching. This showed an extremely favorable environment with extreme instability, moderate deep-layer wind shear, and mid-level lapse rates which were near the record steepest ever recorded at that location.
How did the mid-level lapse rates get so steep?
It is common to get steep lapse rates in the desert. When these overspread moisture, it can provide an environment favorable for powerful storms (A reason why there are so many intense storms in the Plains). It is rare to get lapse rates this steep east of the Mississippi River, but when it happens, storms are commonly more intense than normal ( Banacos & Ekster 2010 ). These mid-level lapse rates originated over the Mojave Desert 60 hours earlier.
72-h backward NOAA HYSPLIT model trajectory of a ≈700-hPa parcel over KFWA ending at 1800 UTC 29 June 2012.
Derecho Tour
01 / 32
1
Near Crete, Illinois
The storm that started it all. 1st image is 0.5 degree scan of reflectivity (left) and echo tops (right) at 1655 UTC from the IWX WSR-88D.
2nd image is a 3D volumetric cube at 1655 UTC from the IWX WSR-88D of reflectivity denoting an intense, tall storm core.
2
Northern Indiana
IWX 0.5 degree reflectivity (left)/velocity (right) loop showing the rapid intensification and expansion of severe thunderstorms across northern Indiana from 1704 UTC to 1850 UTC. Widespread damaging winds of 65 to 85 mph develop within this line segment over the next two hours.
2nd image is from the late Dr. Thedore Fujita, University of Chicago. His groundbreaking, pioneering research in the late 1970's and early 80's was instrumental in understanding not only tornadoes but also bow echos and derechos. His Project NIMROD field study led to the conceptual model of the life cycle of a bow echo and greatly increased the meteorological understanding of the complex mechanisms involved in their development.
3
Fort Wayne Airport, Indiana
A measured wind gust of 91 mph occurred at the Fort Wayne ASOS at 1854 UTC. Widespread damage to power infrastructure and trees throughout Fort Wayne and surrounding communities. This video just south of Fort Wayne captures the powerful force of the derecho winds.
2nd image is 0.5 degree scan of reflectivity (left) and velocity (right) at 1855 UTC from the IWX WSR-88D. Red to orange color indicate winds blowing away from the radar. 3rd image is a 3D volumetric display of velocity data. Tan to orange colors indicate winds in excess of hurricane force.
4
Columbus Grove, OH
City is devastated by estimated 100+ mph winds.
5
Findlay, OH (Hancock County)
Extensive damge was reported with the derecho in the Findlay, OH area. The southern parts of Findlay were especially hard hit with extensive tree and structural damage to homes. A wind gust of 84 mph was reported at 2015 UTC. Other areas across Hancock County also reported extensive damage to trees and power lines.
In the following radar images, the velocity outbounds and inbounds converge into each other in the mid-levels. This is known as the mid-altitude radial convergence (MARC) signature, which can indicate strong surface winds within a squall line. Typically a 50 kt measurement of a MARC can signify severe winds, and in this case a 70 kt MARC was measured over Findlay seen in image 3. A vertical cross section of the radial velocity in image 4 depicts the descending rear inflow jet and the ascending updraft, both of which were responsible for the intense winds in the Findlay area. Another cross section of radar reflectivity in image 5 showed the development of a strong core aloft and the soon after descent of that core, resulting in a particularly intense area of winds up to 84 mph in the Findlay area.
6
Mansfield, OH
As the derecho approached Mansfield, a well defined shelf cloud was photographed with a green core behind it indicating wind driven heavy rain and hail.
7
Marion, OH
In addition to widespread damaging winds, a few instances of very large hail were reported along the path of the derecho, particularly across northern Ohio where golf ball sized hail was reported near Marion, OH. The image on the right indicates a vertical cross section of reflectivity depicting 60 dBZ echoes up to about 35,000 feet above ground level indicating a significant hail core.
8
NWS Wilmington - Special Sounding
A special sounding was released by the NWS Wilmington, OH during the mid afternoon on June 29th in advance of the derecho. The results from this balloon launch indicated that the atmosphere was extremely unstable and would support maintenance of the storms as the derecho swept across Ohio.
9
Marysville, OH
Another instance of very large hail to 2 inches diameter was reported near the Marysville, OH area in the late afternoon on June 29th. This portion of the derecho that affected the Marysville area had 50 dbZ radar reflectivities up to around 50,000 feet as shown in the volume cross section.
10
Columbus/Lancaster, OH
Columbus, OH suffered extensive damage from the derecho, particularly across the northern portions of the city. A wind gust of 72 mph was reported at the John Glenn Columbus Regional Airport (KCMH) at 2106 UTC. Data from the ILN radar indicated echo tops around 50,000 feet with storms moving across the northern portions of Columbus, OH.
Extensive damage was also reported across Fairfield County including the Lancaster, OH area with several reports of trees and power lines down across the county.
11
South of Coshocton, Ohio
The derecho continued to cause damage across portions of eastern Ohio. This barn south of Coshocton, OH was destroyed by the winds.
2nd image, ILN WSR-88D radar 0.5 degree reflectivity (left)/velocity (right) at 2149 UTC, as this intense band of severe thunderstorms is about to swallow Coshocton, OH.
12
Cambridge and Byesville Ohio
Additional widespread wind damage was reported in Cambridge and Byesville, OH.
2nd image, ILN WSR-88D radar 0.5 degree reflectivity (left)/velocity (right) at 2203 UTC. Doppler measured winds in excess of 70 knots (80 mph) are poised to wallop both cities shortly.
13
Ellenboro, WV
A transmission tower was destroyed as the derecho moved through the region around 2300 UTC.
RLX WSR-88D radar 0.5 degree reflectivity (left)/velocity (right) at 2250 UTC. Note the intense storm in reflectivity near Petroleum, WV, southwest of Ellenboro. Velocity data, however, is subdued as it is sampling the line of storms around 6100 feet and not a true measure of near surface winds.
14
Yeager Airport - Charleston, WV
A measured wind gust of 78 mph occurred at approximately 2317 UTC on June 29th at the Yeager Airport ASOS in Charleston, resulting in damage to a hangar. Additionally, a small single engine plane was flipped on the tarmac.
In the local Charleston area, multiple reports were received of downed trees, along with some structural damage and power outages. A prolonged heat wave would continue for over a week after the derecho, making for difficult cleanup conditions, as well as for those who remained without power. High temperatures topped out in the 90s or above for nine straight days following the event.
RLX WSR-88D radar loop of 0.5 degree reflectivity (left)/velocity (right) from 2259-2326 UTC. Note the prominent southeast surge of this intense line of storms across Charleston proper. Doppler measured winds peaked around 80 mph.
15
North Central West Virginia Airport - Bridgeport, WV
A measured wind gust of 66 mph occurred at approximately 2328 UTC on June 29th at the North Central West Virginia Airport ASOS in Bridgeport. Large trees were reported down in Bridgeport with roof damage to homes.
RLX WSR-88D radar 0.5 degree reflectivity (left)/velocity (right) at 2326 UTC. Note the intense storm reflectivity surge taking place from Clarksburg north through Enterprise, WV. Velocity data, however, is sampling the line of storms around 10,000 feet here.
16
Flemingsburg, KY
On the southern periphery of the derecho, an outflow boundary raced southward. Severe wind gusts occurred with this outflow boundary resulting in downed trees and power lines.
A gust of 93 mph was measured on a home weather station near Williamson, KY at 2342 UTC. Trees in excess of 3 feet in diameter were uprooted across much of Pike county Kentucky.
17
Raleigh County Memorial Airport - Beaver, WV
A measured wind gust of 68 mph occurred at approximately 0007 UTC on June 30th at the Raleigh County Memorial Airport ASOS in Beaver. Numerous trees were reported down across the county resulting in a significant number of power outages. All told, an estimated 670,000 customers lost power due to the derecho in West Virginia, with an estimated 3.7 million total customers losing power along the path of the derecho.
FCX WSR-88D radar 0.5 degree reflectivity (left)/velocity (right) at 0003 UTC. Note the intense storms tracking to the north of Beaver, WV with light green and blue relectivities indicating the leading, strong outflow surging to the south. Velocity data here is of little help due to an artifact known as range folding, also known as the Doppler dilemma.
18
Kline Gap, WV
A measured wind gust of 70 mph occurred at approximately 0036 UTC on June 30th just northeast of Kline Gap in Grant County (red dot, center). Numerous trees were reported blown down across the county following the passage of the derecho.
1st image, LWX WSR-88D 0.5 degree reflectivity (left)/velocity (right) at 0035 UTC. Although this line of storms briefly weakened as they crossed the spine of the Appalachian mountains, the associated outflow continued to produce severe winds, and the line reintensified quickly over eastern West Virginia as seen in the 2nd image at 0057 UTC, just 22 minutes later.
19
Bath County, VA
Hundreds of trees were reported blown down across Bath County, in addition to some power lines. Some structural damage to homes was also reported.
FCX WSR-88D radar 0.5 degree reflectivity (left)/velocity (right) at 0025 UTC. Note that even though the line of storms had weakened upon crossing the Appalachian mountains, intense winds were still present and interacting with the higher mountainous terrain to produce widespread wind damage here.
20
Roanoke-Blacksburg Regional Airport - Roanoke, VA
A measured wind gust of 80.6 mph occurred at approximately 0110 UTC on June 30th at the Roanoke-Blacksburg Regional Airport ASOS. This was at the time, and still is, the highest wind gust ever measured at this site. Numerous trees were reported blown down across the area.
It also is important to note the long duration of extreme heat that followed the derecho here. June 30th through July 8th had the warmest average temperature ever in Roanoke (see right), meanwhile thousands of people were without access to air conditioning due to power outages.
2nd image, FCX WSR-88D radar 0.5 degree reflectivity (left)/velocity (right) at 0056 UTC. Doppler measured winds in excess of 70 knots (80 mph) just north of Blacksburg are poised to wallop the city shortly as they spread quickly southward.
21
Wintergreen, VA
A measured wind gust of 87 mph occurred at approximately 0120 UTC on June 30th at the Devils Knob mesonet site (3494 ft elevation) located just northwest of Wintergreen.
FCX WSR-88D 0.5 degree reflectivity (left)/velocity (right) at 0126 UTC. While some reintensification of the line of storms is noted here, intense winds still accompany the outflow boundary as it passes over elevated terrain.
22
Lynchburg, VA
Numerous reports of downed trees and power lines were received from Lynchburg due to the derecho. Some structural damage also did occur as can be seen in the image (right).
FCX WSR-88D 0.5 degree reflectivity (left)/velocity (right) at 0130 UTC. While the line of storms had weakened crossing the Appalachians, intense winds still accompanied the outflow boundary nearing Lynchburg, VA at this time.
23
Berkeley County, WV
Multiple reports of downed trees throughout the county. A mesonet in Bunker Hill only measured a wind gust of 60 mph at approximately 0150 UTC on June 30th. However much stronger winds were observed especially in Martinsburg which sustained widespread, severe tree damage.
Image sequence is a 3-D look of the derecho in far northeast West Virginina at 0139 UTC on June 30th. 1st image is reflectivity (looking northwest from the LWX WSR-88D) showing a rapidly expanding and congealing convective line as it came off the Appalachian mountains. Red colors denote 50+ dBZ, white denote 60+ and are indicative of strong updrafts. Storm tops at this time (not shown) were upwards of 50 thousand feet.
2nd image is velocity. The icy blue colors denote a renewed surge in the rear inflow jet which is about to descend on Martinsburg with 70+ mph winds.
24
Louisa County, VA
The derecho begins to rapidly intensify east of the Appalachians. Trees and power lines were reported down across the county shortly after 0200 UTC on June 30th. Additionally, some structural damage was reported, with trees down on homes and cars in Mineral, VA.
25
Fairfax, VA
City of Fairfax, VA is blasted by 80+ mph winds around 0230 UTC as the derecho continues to rapidly intensify across eastern Virginia.
Widespread, severe tree and power infrastructure damage is reported with trees on houses and cars flattened.
26
Person County, NC
Numerous trees were reported down all around Person County. Northern portions of North Carolina, including this area, ended up being on the southern extent of the derecho's wind damage swath.
RLX WSR-88D 0.5 degree reflectivity (left)/velocity (right) at 0236 UTC. Note the intense winds that still accompany the outflow boundary just southwest of Roxboro, NC at this time.
27
Reagan National Airport - Arlington, VA
A measured wind gust of 70 mph occurred at approximately 0248 UTC on June 30th at the Reagan National Airport ASOS in Arlington. A scene of destruction unfolds across the DC metro as numerous trees were downed leaving over one million people without power. Prior to the derecho moving through, an all time record high temperature for the month of June was set at 104 degrees.
2nd image, GOES enhanced infra-red (IR) satellite image taken at 0240 UTC across the region. Overlaid on this image is the 15 minute sum of cloud-to-ground lightning strikes between 9:30 PM and 9:45 PM EDT. Nearly 1400 strikes are depicted in this image and as seen looking across the Potomac river toward the Jefferson Memorial and Washington Monument.
3nd image, LWX WSR-88D 0.5 degree reflectivity (left)/velocity (right) at 0244 UTC shows a very intense line of severe storms with widespread 70-80 mph winds engulfing Washington DC.
28
Anne Arundel County, MD
A measured wind gust of 66 mph occurred at approximately 0302 UTC on June 30th at the Baltimore/Washington International Airport ASOS in Baltimore. Additionally, a plane was flipped at the Tipton Airport as the derecho moved through.
LWX WSR-88D 0.5 degree reflectivity (left)/velocity (right) at 0309 UTC. After flattening Washington DC, a resurgent derecho is now blasting eastern Maryland.
29
Gloucester, VA
A measured wind gust of 60 mph occurred at approximately 0345 UTC on June 30th in Gloucester. Numerous trees were downed along Highway 14 northeast of the village.
30
Franklin Municipal–John Beverly Rose Airport: Franklin, VA
A wind gust of 74 mph was measured at approximately 0356 UTC on June 30th by the airport's ASOS.
AKQ WSR-88D 0.5 degree reflectivity (left)/velocity (right) at 0350 UTC showing the outflow boundary crossing Franklin, VA.
31
Salisbury, MD
Numerous trees were reported down in the city from the derecho at approximately 0410 UTC on June 30th.
32
South Jersey Coast
As the Derecho approached the coast, it continued to produce severe wind gusts. A gust to 87 mph was recorded at the Atlantic City International Airport. Widespread wind damage was reported across portions of Cumberland, Cape May, and Atlantic Counties in New Jersey.
DIX 0.5 degree reflectivity (left)/velocity (right) at 0511 UTC shows intense winds surging across eastern New Jersey.
Storm Reports
June 29, 2012 Derecho
Additional Resources
If you're interested in learning more about this event or derechoes in general, check out the resources listed below.
Baltimore-Washington NWS Office - Overview of the June 29, 2012 derecho in the Maryland-Virginia area Charleston, West Virginia NWS Office - Overview of the June 29, 2012 derecho in southeast Ohio and West Virginia Jackson, Kentucky NWS Office - Overview of the June 29, 2012 derecho in eastern Kentucky Northern Indiana NWS Office - Overview of the June 29, 2012 derecho in northeast Indiana and northwest Ohio
Cleveland, Ohio NWS Office - A look back at the June 29, 2012 derecho in northwest and north central Ohio 10 years later Wilmington, Ohio NWS Office - Overview of the June 29, 2012 derecho over central / southwest Ohio and northern Kentucky Mount Holly, New Jersey NWS Office - Overview of the June 29, 2012 derecho in northeast Maryland, southeast Pennsylvania, New Jersey, and Delaware Storm Prediction Center - June 29, 2012 Severe Weather Event Archive
National Weather Service Storm Data , 2012-06
Fujita, 1979 T.T. Fujita Objective, operation, and results of Project NIMROD 11th Conf. on Severe Local Storms, Kansas City, MO, Amer. Meteor. Soc (1979), pp. 259-26
