NWS issues report on last June’s historic Derecho

By on February 6, 2013

Radar images of last June's Derecho progression

Radar images of last June’s Derecho progression

The National Weather Service has released an assessment of the historic Derecho that went through Fort Wayne last June 29th. The Derecho moved east to the coast leaving 4 million customers without power, 13 deaths and millions of dollars in damages.

According to the report, Fort Wayne had the highest official report of wind gusts at 91 mph. There was an Acu-rite anemometer 11 miles north-northwest of Cambridge, OH, measured an unofficial peak wind gust of 106 mph.

From the executive summary of the report:

Executive Summary

On June 29, 2012, a devastating line of thunderstorms known as a derecho (deh REY cho) moved east-southeast at 60 miles per hour (mph) from Indiana in the early afternoon to the Mid-Atlantic region around midnight. The states most significantly impacted were Indiana, Ohio, Kentucky, Pennsylvania, West Virginia, Maryland, Virginia, Delaware, New Jersey, and North Carolina, as well as Washington, D.C. Nearly every county impacted by this convective system suffered damages and power outages. Winds were commonly above 60 mph with numerous reports of winds exceeding 80 mph.

Some areas reported isolated pockets of winds greater than 100 mph. The storm resulted in 13 deaths, mainly a result of falling trees. One major impact from the derecho was widespread power outages. More than 4 million customers were without power, some for more than a week after the storms moved through. To make matters worse, the area affected was in the midst of a prolonged heat wave. There were 34 heat-related fatalities in areas without power because of the derecho.

The National Weather Service (NWS) formed a Service Assessment Team to evaluate performance during this event. Due to the widespread nature of this derecho, the team chose to visit the sites and review products and performance only at NWS Weather Forecast Offices (WFO) most impacted by the storms: WFOs Syracuse, IN (hereafter WFO Northern Indiana); Wilmington, OH; Pittsburgh, PA; Sterling, VA; Charleston, WV; and Blacksburg, VA. The team collected data from five other sites on the periphery of the damage path: WFOs Indianapolis, IN; Cleveland, OH; Jackson, KY; Mount Holly, NJ; and Wakefield, VA. A review of the products and services provided by the Storm Prediction Center (SPC) was also conducted along with numerous SPC staff interviews.

Unlike many major tornado outbreaks in the recent past, this event was not forecast well in advance. Warm-season derechos, in particular, are often difficult to forecast and frequently result from subtle, small-scale forcing mechanisms that are difficult to resolve more than 12-24 hours in advance. The National Centers for Environmental Prediction (NCEP) operational forecast models, such as the North American Mesoscale (NAM) and Global Forecast System (GFS), provided little assistance in forecasting this event more than 24 hours ahead of time. However, on the morning of June 29, some high-resolution, convection-allowing models began to provide clues that an intense line of thunderstorms could take the path that was later observed.

Because decision support activities were delayed until close to the event, key partners and decision makers had less time to prepare for the severe winds. In the Mid-Atlantic region, many forecasters thought the derecho would follow climatology and break up crossing the Appalachian Mountains. This past pattern for such events impacted the SPC’s outlooks, which did not extend the risk for severe thunderstorms eastward to the Mid-Atlantic coast until the afternoon of June 29. Therefore, WFO products and services, as well as preparedness efforts, were affected because the WFOs followed SPC guidance closely.

Despite the relatively short lead time for forecasting this event, the offices generally did an excellent job issuing warnings. Overall, lead times were greater than 30 minutes, especially on the eastern end of warning polygons. Most of the offices were issuing large warning polygons to cover the widespread nature of the event and the fast storm motion. All deaths occurred within severe thunderstorm warning polygon boundaries.

Three social scientists were included on this Service Assessment Team to help determine the societal impacts of this event and to suggest improvements to future services. The social scientists worked side by side with other team members participating in a wide range of briefings, interviews, and site visits. Consequently, many of the recommendations in this assessment report incorporate a social science perspective. A common theme that emerged from talking to emergency managers, media, and the public was that although they received the warnings, they were surprised by the intensity of the winds.

The team submitted 13 recommendations to address NWS performance, safety, and outreach programs. In addition, the team identified five best practices. Appendix B includes definitions of facts, findings, recommendations, and best practices followed by a complete listing of findings, recommendations, and best practices found within the main body of the report. Appendices C and D contain information concerning the deaths from the derecho and from heat. Appendix E provides a list of measured gusts greater than 57 mph recorded during this event.

 

The Summary:

A historic derecho impacted the Ohio Valley and Mid-Atlantic states on June 29, 2012. The event originated in northeast Illinois as a small cluster of thunderstorms. The derecho became organized over northeast Indiana during the afternoon and raced southeastward across Ohio and West Virginia at 60 mph. The derecho remained intact crossing the Appalachians, a climatological rarity, and caused widespread damage in the Washington, D.C., metropolitan area during the late evening. The derecho moved offshore shortly after midnight on June 30, 2012. In its wake, 13 people were killed and several million customers were left without power, many for several days. Tony Cavalier, Chief Meteorologist from WSAZ-TV Huntington-Charleston, WV, was quoted as saying, “The derecho was one of the top two impacting events in my 25 year career.”

This derecho was not forecast until the day of the event. Summertime derechos are often difficult to forecast because they respond to smaller-scale forcing mechanisms. Despite the extreme instability available for thunderstorms in the region affected by the derecho, the NCEP operational models were not indicating any disturbances that would help initiate and organize thunderstorms. This delayed the onset of decision support services and the use of enhanced wording in forecasts and hazardous weather outlooks.

On the day of the event, some of the CAMs that more closely simulate thunderstorms were developing an MCS over the area impacted. This allowed the SPC and WFOs to reflect the seriousness of the threat in their product suite. Much of the high-resolution, CAMs data are experimental and not available in the Day 2 forecast time period. Fully supported, ensemble, high-resolution model data extending further out in time are needed to improve the lead time in forecasting these extreme wind storms. Without these data, many of these derecho events will continue to have forecast lead times of 24 hours or less.

Numerous interviews with the public, media, and EMs revealed that despite accurate severe thunderstorm warnings and enhanced wording used by most of the WFOs, nearly everyone surveyed was surprised by the intensity of the winds during this event. NWS should move toward an impact-based severe thunderstorm warning so partners and the public receiving warnings have a better understanding of the storm’s severity.

The heat was a significant concern after this derecho, especially because of the widespread power outages. A heat wave that was building in the days leading up to the derecho continued for about a week after the event. More people died because of the heat in the days following the storm than from the derecho itself: 34 versus 13. Several WFOs lowered their heat advisory criteria in the areas hit hard by power outages by as much as 10 oF. NWS heat products should include an impact statement emphatically expressing the dangers of remaining in homes without air conditioning during prolonged heat waves.

 

Download the assessment

 

About Stephen Parker

Stephen Parker is the blogmaster for AroundFortWayne.com. He believes that everyone should have access to information, interviews, and videos of events that are, "Straight from the source". When not blogging, he enjoys outdoor activities in his adopted home, Fort Wayne Indiana. He moved here in late 1989 and hasn't looked back.

Facebook

Twitter

YouTube

Google Plus

Follow Me on Pinterest
  • A group of House Republicans criticized the Obama administration Wednesday over news that schools are cutting their employees' hours to avoid providing health insurance. Read more: http://thehill.com/blogs/healthwatch/health-reform-implementation/305073-gop-schools-cutting-workers-hours-to-avoid-obamacare-penalty

    Pinned: 13 Jun 2013
  • Mayor Bloomberg’s $12 million ad blitz to drum up Senate support for background checks on all gun purchases could backfire, Senate strategists said Monday.

    Pinned: 26 Mar 2013
  • Article about smart parking.

    Pinned: 25 Mar 2013
  • US Congressman Marlin Stutzman (R-IN 3rd): “This Budget Debate Goes Deeper than Spreadsheets and Focuses on the Longevity of the American Dream”

    Pinned: 20 Mar 2013
  • "What's a severe thunderstorm or tornado watch?" "How's it different from a warning?" "What actions should be taken when a watch is issued?" Get the answers to these frequently asked questions here!

    Pinned: 5 Mar 2013
  • “The President’s doomsday scenarios are of his own choosing,” Rep. Marlin Stutzman, R-Ind., argued in response to Cutter’s email. “The sequester will cut 2.3 percent, or $85 billion, from the massive $3.55 trillion the federal government is projected to spend this year alone. To put that percentage in perspective, we borrow that much money every 28 days. If the President can’t cut that much, he’ll never cut anything.”

    Pinned: 5 Mar 2013
  • Photos and Video from the 2009 Get Green event.

    Pinned: 4 Mar 2013
  • Multimedia weather briefing concerning the winter storm to impact the area Thursday night into Friday. Created at 4:00pm Thursday 2/21/13.

    Pinned: 21 Feb 2013
  • Preliminary renderings from the City of Fort Wayne for the State Boulevard project.

    Pinned: 20 Feb 2013
  • Squad cars adding cameras, license plate readers

    Pinned: 20 Feb 2013

Instagram

Follow Me on Instagram
  • Looking north on Broadway from the fountain. #FortWayne

    aroundfortwayne: "Looking north on Broadway from the fountain.

#FortWayne"
    15
    0
  • There's Trubble Brewing on Broadway. Preparations are still underway for their opening. It's good to see a business back in that building! For another photo and link to their Facebook page, visit - http://www.aroundfortwayne.com/?p=54729 #FortWayne

    aroundfortwayne: "There's Trubble Brewing on Broadway. Preparations are still underway for their opening. It's good to see a business back in that building!

For another photo and link to their Facebook page, visit - http://www.aroundfortwayne.com/?p=54729

#FortWayne"
    31
    1
  • The fountain on Broadway this pleasant afternoon. #FortWayne

    aroundfortwayne: "The fountain on Broadway this pleasant afternoon.

#FortWayne"
    21
    0
  • Work on the West Jefferson gateway continues. For more information and a news release about the project, visit - http://www.aroundfortwayne.com/?p=54629 #FortWayne

    aroundfortwayne: "Work on the West Jefferson gateway continues. For more information and a news release about the project, visit - http://www.aroundfortwayne.com/?p=54629

#FortWayne"
    9
    0
  • James & The Drifters on the Banks at last night's Bands on the Banks. August 15, 2015. #FortWayne #RiverfrontFW @fortwayneoutfitters

    aroundfortwayne: "James & The Drifters on the Banks at last night's Bands on the Banks. August 15, 2015.

#FortWayne #RiverfrontFW  @fortwayneoutfitters"
    15
    0
  • People on the Banks.... ....for Bands on the Banks at the Fort Wayne Outfitters & Bike Depot on the St. Marys River in downtown Fort Wayne. Photo taken August 15, 2015. #FortWayne #RiverfrontFW

    aroundfortwayne: "People on the Banks.... ....for Bands on the Banks at the Fort Wayne Outfitters & Bike Depot on the St. Marys River in downtown Fort Wayne. Photo taken August 15, 2015.

#FortWayne #RiverfrontFW"
    19
    0
  • Bands on the Banks tonight at the Fort Wayne Outfitters & Bike Depot. Here's a clip of a Time-lapse video shot last year during a concert on July 24, 2015. For the full video, in even better resolution and a link to information about tonight's concert, go here - http://www.aroundfortwayne.com/?p=54506 #FortWayne @fortwayneoutfitters

    aroundfortwayne: "Bands on the Banks tonight at the Fort Wayne Outfitters & Bike Depot. Here's a clip of a Time-lapse video shot last year during a concert on July 24, 2015.

For the full video, in even better resolution and a link to information about tonight's concert, go here -

http://www.aroundfortwayne.com/?p=54506

#FortWayne @fortwayneoutfitters"
    15
    0
  • Another day, another bridge... *Le sigh* The pedestrian bridge into Swinney Park East, located just off Mechanic and Main Streets over the St. Mary's River on August 11, 2015. Instagram doesn't do justice to the full photo. Check it out here - http://www.aroundfortwayne.com/?p=54500 #FortWayne

    aroundfortwayne: "Another day, another bridge... *Le sigh*

The pedestrian bridge into Swinney Park East, located just off Mechanic and Main Streets over the St. Mary's River on August 11, 2015.

Instagram doesn't do justice to the full photo. Check it out here - http://www.aroundfortwayne.com/?p=54500

#FortWayne"
    12
    0
  • Rollin' on the bridge over the river... Norfolk Southern runs one of its Triple Crown Roadrailer trains over the former Wabash Railroad Bridge over the St. Marys River on August 11, 2015. Additional photo - http://www.aroundfortwayne.com/blog/?p=54493

    aroundfortwayne: "Rollin' on the bridge over the river... Norfolk Southern runs one of its Triple Crown Roadrailer trains over the former Wabash Railroad Bridge over the St. Marys River on August 11, 2015.

Additional photo - http://www.aroundfortwayne.com/blog/?p=54493"
    21
    0
  • The former Coca-Cola facilities along Pontiac Street on August 3, 2015. More photos - http://aroundfortwayne.rocks/photos/thumbnails-25.html #FortWayne

    aroundfortwayne: "The former Coca-Cola facilities along Pontiac Street on August 3, 2015.

More photos - http://aroundfortwayne.rocks/photos/thumbnails-25.html

#FortWayne"
    12
    0