On August 10th, an intense derecho brought severe to extreme winds to much of the Midwest with winds estimated as high as 130 to 140 mph in Iowa. As the derecho neared Indiana, the storms were not quite as intense, but did produce measured winds up to 70 mph and caused significant tree damage and power outages to the local area.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS IND wrote it up.
On August 10th, an intense derecho brought severe to extreme winds to much of the Midwest with winds estimated as high as 130 to 140 mph in Iowa. As the derecho neared Indiana, the storms were not quite as intense, but did produce measured winds up to 70 mph and caused significant tree damage and power outages to the local area. Over 100,000 people were without power at one point with power outages lasting several days across portions of the state.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Indianapolis, IN wrote its last area forecast discussion before the first event at Aug 10, 4:18 PM EST, 42 minutes earlier.
Area Forecast Discussion National Weather Service Indianapolis IN 518 PM EDT Mon Aug 10 2020 .UPDATE... Mesoscale Section Included in this AFD issuance. .SYNOPSIS... Issued at 340 PM EDT Mon Aug 10 2020 Severe weather is likely this evening with the main threat being damaging winds across the region. An unsettled pattern remains for much of the forecast period leading to daily chances for rain and storms. && .MESOSCALE /5PM through 7PM/... Issued at 512 PM EDT Mon Aug 10 2020 Satellite mesoscale sector setup this afternoon over the cornbelt of Illinois/Indiana showing the line of intense convection moving east across Northeast Illinois and stretching Southwest through Central Illinois. The forward propagation of this line appears to be trying to turn southeast, where a scattered cumulus field exists. Surface observations across Central Indiana at 5PM are becoming more uniform with considerable low-level atmospheric moisture present, especially within the 0-1KM layer where added evapotransporation is taking place. Dewpoints have pushed well into the 70s, with winds veering more to the southwest. Gusts are starting to creep up as well, ranging between 15 to 20 kts at times with some tightening in the pressure fields taking place. Guidance soundings suggest considerable amount of energy within the convective layer this afternoon will slowly diminish as the evening progresses; however, still robust convective potentional as the line of severe weather pushes east towards Indiana. Thermal soundings are rather steep as well, which will further aid in convective maintenance throughout this evening across Central Indiana. The cold pool production remains to be of concern with this intense convective line, coupled with the extremely unstable atmosphere over Central and Northcentral Indiana, that as the convective system progresses east the dominant feature will be widespread intense wind. Severe winds in excess of 80mph is common with atmospheric conditions similar to what is present over Central and Northern Indiana this evening. && .NEAR TERM /Rest of This Afternoon and Tonight/... Issued at 338 PM EDT Mon Aug 10 2020 ...Significant Severe Weather with Widespread Damaging Winds to Impact central Indiana This Evening... After the stormy start to the morning for some...skies had cleared across central Indiana. With deep moisture and strong heating... temperatures have shot up into the mid and upper 80s over much of the forecast area as of 19Z. Low 90s had developed along the Wabash Valley. With oppressive dewpoints ranging from the mid 70s to near 80...heat indices were in the 90s and low 100s currently. The focus for the next several hours is on a high confidence...high impact derecho with widespread damaging winds that began early this morning in the northern Plains and now sits in eastern Iowa and western Illinois. The amount of observed wind reports in excess of 90 mph from this complex over Iowa is for lack of a better term... alarming. The airmass this afternoon has the feel of a capped powder keg and mesoanalysis shows that SBCAPEs have surged since late morning...and are now in excess of 5000 j/kg. With a few more hours of heating...these values are likely to only increase ahead of the approaching convective complex. In addition...mid level lapse rates have increased to near 8 C/km immediately downwind of the derecho and now into our western counties. The complex has a well developed cold pool that will keep its engine running for the next several hours. In an nutshell...the airmass downstream of the convective complex supports a continued high confidence in severe weather across northern and central Illinois and by this evening...across the forecast area as the complex is likely to pivot and follow the theta- e ridge and instability gradient right into central Indiana. All severe threats are on the table but clearly...the damaging wind concerns are greatest considering what has already taken place...a strengthening westerly low level jet and the amount of instability already in place across the area. Timing for greatest impacts will be from northwest to southeast from 22Z through 02-03Z. In addition to the severe weather concern... flooding will become a threat...particularly in areas that saw 1-2 inches this morning. Also...derechos tend to be prolific lightning producers and the approaching convective cluster certainly appears to be just that. Should see convection diminish in coverage after midnight...although the presence of the westerly 850mb jet at least initially in the overnight may enable a backbuilding component to convection. Will maintain chance pops through the overnight although the greater risk for rain is the first half of the night. Temps...did not stray from NBM guidance too much as lows should fall back into the upper 60s and lower 70s overnight in wake of the convective complex. && .SHORT TERM /Tomorrow through Thursday/... Issued at 340 PM EDT Mon Aug 10 2020 The area will wit under an unsettle pattern for the short term as a couple of disturbances move overhead. This will lead to daily chances of scattered rain and storms. Best PoPs at the moment are for late tomorrow through Wednesday... could possibly see a weak surface low pass through bringing in the rain. Temperatures look to be near to slightly above normal with highs in the mid 80s and lows in the upper 60s. && .LONG TERM /Thursday Night through Monday/... Issued at 340 PM EDT Mon Aug 10 2020 A couple of disturbances look to impact the area in the long term, prompting daily rain chances. Models show a cold front passing through the area sometime Sunday to Monday... should get a better idea on timing as it gets closer. Temperatures will be near normal. Largely accepted guidance as it looked reasonable. && .AVIATION (Discussion for the 102100Z TAF Update)... Issued at 425 PM EDT Mon Aug 10 2020 Added gusts to KIND winds to match recent trends. Left timing of convection alone for now but will continue to watch for later refinements. Previous discussion follows.... ...Severe storms this evening may cause significant impacts to terminal operations... Skies had largely cleared after the convection earlier this morning. Focus though now has shifted to a convective cluster over Iowa that has a history of widespread damaging winds. This cluster will continue to track southeast through the afternoon and is expected to sweep through central Indiana this evening. With higher confidence in wind impacts with the storms...have introduced 2 hour tempo groups with 40kt gusts from the northwest at and sub IFR conditions within the convection at all terminals. It should be noted that these wind values may need to be raised later this afternoon. Convection should be through the terminals by late evening...but additional storms are possible overnight before conditions improve on Tuesday morning. May see lingering MVFR ceilings into Tuesday morning before clouds mix out. Outside of the storms...winds && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && SYNOPSIS...KH MESOSCALE...Beach NEAR TERM...Ryan SHORT TERM...KH LONG TERM....KH AVIATION...Ryan/50
Hazardous Weather Outlook National Weather Service Indianapolis IN 244 PM EDT Mon Aug 10 2020 INZ021-028>031-035>049-051>057-060>065-067>072-111845- Carroll-Warren-Tippecanoe-Clinton-Howard-Fountain-Montgomery-Boone- Tipton-Hamilton-Madison-Delaware-Randolph-Vermillion-Parke-Putnam- Hendricks-Marion-Hancock-Henry-Vigo-Clay-Owen-Morgan-Johnson-Shelby- Rush-Sullivan-Greene-Monroe-Brown-Bartholomew-Decatur-Knox-Daviess- Martin-Lawrence-Jackson-Jennings- Including the cities of Delphi, Flora, Williamsport, West Lebanon, Lafayette, West Lafayette, Frankfort, Kokomo, Attica, Covington, Veedersburg, Crawfordsville, Lebanon, Zionsville, Tipton, Fishers, Carmel, Noblesville, Anderson, Muncie, Winchester, Clinton, Newport, Rockville, Greencastle, Plainfield, Brownsburg, Danville, Indianapolis, Greenfield, Cumberland, New Castle, Terre Haute, Brazil, Clay City, Spencer, Martinsville, Mooresville, Greenwood, Franklin, Shelbyville, Rushville, Sullivan, Linton, Bloomfield, Bloomington, Nashville, Columbus, Greensburg, Vincennes, Washington, Loogootee, Shoals, Bedford, Mitchell, Seymour, Brownstown, and North Vernon 244 PM EDT Mon Aug 10 2020 This hazardous weather outlook is for central Indiana. .DAY ONE...This Afternoon and Tonight. Outlook: Severe thunderstorms expected this evening. Hazards: Widespread damaging winds likely, frequent lightning, and heavy rain that may lead to localized flooding. Timing: Primarily 6 to 11 PM. A second wave of storms may produce primarily heavy rain across southwestern portions of central Indiana after 3 AM. Discussion: An approaching cold front has produced an extremely strong line of severe thunderstorms to our northwest. This line of storms is expected to move across portions of central Indiana in the 6 to 11 PM time frame, with widespread damaging winds likely. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. Outlook: Periodic thunderstorms are possible each day. Lightning and heavy rain are possible with any thunderstorm. Discussion: A front will linger in the area through the week, keeping chances for thunderstorms in the forecast. .SPOTTER INFORMATION STATEMENT... Spotter activation will likely be needed this evening. .STORM MOTION STATEMENT... Storm motion is expected to be from the west northwest at 50-55 MPH. && More information, along with other weather, hydrological and climate information can be found at http://weather.gov/ind
The Indianapolis radar (KIND), 112 km away, was scanning. The volume nearest the first event began at 21:58 UTC.
46 thunderstorm wind, 1 flood, 1 flash flood. Local standard time, as filed.
Gust front ahead of line of storms caused power outage. 30 to 40 mph winds continued for several minutes after initial gust of 60 mph.
A tree of unknown size was blown over due to thunderstorm wind gusts.
A 70 mph wind thunderstorm wind gust was estimated at this location.
Numerous trees and limbs downed due to thunderstorm wind gusts around Battle Ground Indiana. Video and lots of pics of tree damage were received. Also, widespread power outages from Battle Ground to Burrows reported with much of Delphi without power.
A 67 mph thunderstorm wind gust was measured at this location.
A 16 inch diameter tree was uprooted due to thunderstorm wind gusts at this location.
A 63 mph thunderstorm wind gust was measured at this location.
Trees of unknown size downed due to thunderstorm wind gusts across Old Indiana 25 going into Delphi at the Carroll and Tippecanoe county border going down the hill.
A 70 mph thunderstorm wind gust was estimated at this location.
A 65 mph thunderstorm wind gust was measured at this location.
A 70 mph thunderstorm wind gust was measured at SR 26 and 750 W.
A 60 to 70 mph thunderstorm wind gust was estimated at Fruitridge Avenue and Plum Street.
Power lines downed due to thunderstorm wind gusts along south 7th st and across the rest of town.
Six to eight inch diameter tree limbs were blown down by thunderstorm winds.
An 18 to 24 inch diameter tree downed at the 4000 block of county road 1100s near Reelsville. 3 power poles were snapped near the location. Fire rescue made 12 downed tree calls during the evening with 30 to 40 across the county.
An estimated 12-18 inch diameter tree was blown down into the road due to thunderstorm wind gusts. Live power lines were also downed at the 4000 block of Sycamore St.
A 12 inch diameter tree limb was blown down by thunderstorm winds at the intersection of State Road 39 and County Road 1025 north.
A 10 inch diameter tree was blown down by thunderstorm winds at the 500 block of north maple street.
A live 24 inch diameter tree was blown down by thunderstorm winds at the intersection of County Road 275 East and County Road 1000 North.
A six to eight inch diameter tree was blown down onto utility lines due to thunderstorm wind gusts. Power line was snapped in 4 locations due to the fallen tree with power out for more than 36 hours.
A tree of unknown size was blown down by thunderstorm winds.
A tree roughly 18 inches in diameter was snapped due to thunderstorm wind gusts and fell onto utility lines.
Thunderstorm winds blew down a 14 to 16 inch diameter tree across the road near or at the intersection of County Road 625 East and County Road 300 South.
A large tree limb approximately 8 to 10 inches in diameter was blown down by thunderstorm wind gusts.
Over 50 reports of trees and power lines downed by thunderstorm wind gusts. Most of which were in Anderson, Alexandria, and Elwood.
A tree and power lines were blown down from thunderstorm winds at County Road 200 South and Dan Jones Road.
Numerous trees of unknown size were downed by thunderstorm wind gusts.
One tree of unknown size was blown down into a house near Anderson University by thunderstorm winds.
A pear tree was blown down by thunderstorm wind gusts.
A 12 inch diameter tree limb was blown down by thunderstorm winds.
Thunderstorm winds snapped off a 36 inch diameter live tree at its base.
A 61 mph thunderstorm wind gust was measured at the KIND ASOS.
Reports of trees and power lines downed due to thunderstorm wind gusts. Nearby a few shingles and siding were blown off a business in northern Anderson and Frankton.
Trees were blown down by thunderstorm wind gusts just west of Linwood. Time approximate.
A 65 mph thunderstorm wind gust was measured at this location.
A 60 mph thunderstorm wind gust was estimated at this location.
Eight to ten inch diameter trees or tree limbs were blown down by thunderstorm winds.
At the 100 block of North and Apple street there are several 10 to 12 inch diameter live tree limbs downed due to thunderstorm winds.
A twelve inch diameter live tree was blown down at its base by thunderstorm winds near County Roads 600 W and 700 S.
I-65 southbound at the 111.7 mile marker near I-70 right two lanes of the interstate have standing water.
Trees down into power lines at Beech Tree and Nineveh roads. 18 other reports of trees down across Brown County.
A 25 inch diameter live with significant rot was blown down onto a road by thunderstorm winds.
A 60 mph thunderstorm wind gust was measured at this location.
Twelve inch diameter tree limbs were blown down from thunderstorm winds.
Power lines downed by tree limbs that were knocked down by thunderstorm wind gusts.
Power lines downed by falling tree limbs due to thunderstorm wind gusts.
Numerous trees and several power lines downed by thunderstorm wind gusts across Jackson county.
Flash flooding occurred around Brownstown and Washington township. Water was flowing over several roads in town with highway department closing roads.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Indiana in 2020Every state in 2020This day in weather historyWarnings in Indiana, August 2020
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 903633, 903635, 903634, 903638, 903652, 903641, 903650, 903639, 903649, 903655, 903658, 903657, 903659, 903660, 903661, 903663, 903666, 903664, 903665, 903669, 903667, 903668, 903670, 903672, 903675, 903673, 903674, 903676, 903677, 903662, 903678, 903679, 903680, 903681, 903685, 903696, 903682, 903684, 903687, 903688, and more.