During the daytime hours of March 18th, a strong weather system was moving through Indiana with periods of strong gradient winds much of the day with periods of heavy rain during the afternoon and evening hours. Overall impacts were fairly minimal, but a few stronger gusts caused isolated damage.
Every event with a place to put it; 4 filed by county or forecast zone are drawn at its center, in a lighter ring. 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.
During the daytime hours of March 18th, a strong weather system was moving through Indiana with periods of strong gradient winds much of the day with periods of heavy rain during the afternoon and evening hours. Overall impacts were fairly minimal, but a few stronger gusts caused isolated damage.
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 Mar 18, 5:08 AM EST, 1 hour 13 minutes earlier.
Area Forecast Discussion National Weather Service Indianapolis IN 608 AM EDT Thu Mar 18 2021 ...Updated Aviation Discussion... .Short Term...(Today through Friday) Issued at 311 AM EDT Thu Mar 18 2021 ...Wind Advisory from 8 AM to 8 PM Today... Widespread rain with a few storms is expected for today as an upper level low pressure system passes through the Midwestern states. As of early this morning, the surface low pressure system was crossing into southern Illinois. During much of the overnight hours, precipitation has struggled to make it very far into Indiana which seems to be due to the fact that much of the moisture has been robbed by the convection across the southern Gulf states. Surface flow remains easterly with little additional moisture advection. Do think that rain will slowly become more widespread later this morning as the low pressure moves closer and the strong low to mid level lift arrives. The threat for thunder appears fairly minimal with the expected falling temperatures today, so will cap the mention at just SChc. With the overall lack of strong convection, that should also lead to slightly lower QPF amounts compared to what previous forecasts had, but with the fairly persistent rain, still expected amounts of around an inch for much of the area. The primary concern for the daytime hours looks to be strong winds with the core of the 850mb LLJ over the area by mid afternoon. That combined with the increasing pressure gradient forces should bring winds to around 40- 45 mph at times for much of the forecast area. The main question will be whether the precipitation and clouds limit the depth of the mixing layer, but models seem to show an area of nearly dry adiabatic winds up to around 900mb which should be just deep enough to tap into those higher winds. Will make a slight southward expansion of the wind advisory to account for the increased confidence in these higher winds. The surface low will pass to the south and after 00Z will be southeast of the forecast area. After that point forcing quickly comes to an end as Indiana ends up on the northwestern side of the surface low. Do think there may be a brief period where snow is possible, but overall coverage should be minimal with precipitation generally ending before temperatures fall to near freezing. As the low exits, winds should come down enough to be below criteria for the Wind Advisory by around the same time. Clouds will quickly move out late tonight which should allow for temperatures to drop into the upper 20s. Dry and quiet weather then arrives for Friday as skies clear. CAA behind the system will keep temperatures seasonably cool but with the strong sun, conditions will feel closer to normal. && .Long Term...(Friday night through Wednesday) Issued at 311 AM EDT Thu Mar 18 2021 ...Dry and Pleasant Late Week through Monday... ...Potential Severe Weather and Flooding Pattern Emerges Mid Week... Long term period looks to start on a dry, pleasant, and warming note as high pressure dominates the area at the surface and aloft. A very dry column noted in forecast soundings, and as time goes on expect a more and more well mixed afternoon boundary layer across the area. Currently in the vegetation preemergence portion of the spring where guidance tends to underestimate mixing impacts on dewpoints, and to a degree on temperatures, as well as when models tend to take a bit to fully incorporate the impact of increasingly strong spring sunshine. Have made adjustments during the dry period to increase diurnal temperature range, particularly on the max temp side, and to better depict mixing out of very shallow, gradually moistening dewpoints as time goes on and southerly flow begins to establish itself. This will likely have implications for fire weather conditions down the line. As we get through what should be a very pleasant weekend and get into early next week, the next longwave trough pushes into the western US and begins to wrap up/close off another strong low pressure system over the panhandles, hooking it up into the upper Great Lakes during the work week. This will require a return of precipitation chances as early as Tuesday and continuing through the remainder of the period. Some model depictions of the first of what may be two low pressure systems depict an overall evolution and track not that dissimilar from what local research has shown to be potential severe weather producers, and will have to monitor this evolution, and particularly timing, closely as we get toward Tuesday and Wednesday. CIPS analogs show some solid support for this, albeit with all the caveats that come with a time horizon of day 6-7. Upper level flow in the larger longwave trough becomes quite meridional/boundary parallel with the second low pressure system as the tail end of the baroclinic zone slows near the very end of the forecast period/midweek next week, and another shortwave or closed low pivots through the longwave trough. This setup could produce a direct fetch of tropical moisture into the area, and along with the forcing aligned parallel to the slowed boundary, produce a setup mid week for possible heavy rain and hydrologic issues. This will also need close monitoring over the next several days. && .Aviation...(12Z TAF Issuance) Issued at 608 AM EDT Thu Mar 18 2021 IMPACTS: -IFR to LIFR cigs through much of the day, becoming IFR after 00Z this evening -MVFR to IFR vsbys through the afternoon. Thunder possible, most likely at BMG -Northeasterly winds becoming northerly. Wind gusts up to 35-40kts at times today. DISCUSSION: Widespread rain to continue through much of the day leading to IFR to LIFR vsbys and cigs. Isolated thunder is possible through the morning hours with best chances at BMG. Winds will gradually become more northerly through the day with frequent gusts in excess of 30kts and occasional gusts up to 40kts. Rain will come to an end after 00Z with a gradual weakening of winds through the overnight hours along with improvement to VFR cigs. && .IND WATCHES/WARNINGS/ADVISORIES... Wind Advisory until 8 PM EDT this evening for INZ021-028>031- 035>049-051>057-065. && Short Term...White Long Term...Nield Aviation...White
Hazardous Weather Outlook National Weather Service Indianapolis IN 323 AM EDT Thu Mar 18 2021 INZ060>064-067>072-190730- Sullivan-Greene-Monroe-Brown-Bartholomew-Knox-Daviess-Martin- Lawrence-Jackson-Jennings- Including the cities of Sullivan, Linton, Bloomfield, Bloomington, Nashville, Columbus, Vincennes, Washington, Loogootee, Shoals, Bedford, Mitchell, Seymour, Brownstown, and North Vernon 323 AM EDT Thu Mar 18 2021 This hazardous weather outlook is for central Indiana. .DAY ONE...Today and Tonight. A few thunderstorms are possible through the late morning hours. Storm motion will generally be to the northeast at 20-30 mph. Outside of storms, winds will occasionally gust up to 40 mph through the evening. Rainfall amounts of around an inch today may lead to isolated flooding of poorly drained areas. .DAYS TWO THROUGH SEVEN...Friday through Wednesday. Thunderstorms are possible Tuesday night through Wednesday. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated. && More information, along with other weather, hydrological and climate information can be found at http://weather.gov/ind INZ021-028>031-035>049-051>057-065-190730- 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-Decatur- 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, and Greensburg 323 AM EDT Thu Mar 18 2021 This hazardous weather outlook is for central Indiana. .DAY ONE...Today and Tonight. A few thunderstorms are possible through the late morning hours. Storm motion will generally be to the northeast at 20-30 mph. Outside of storms, winds will occasionally gust up to 50 mph through the evening. Rainfall amounts of around an inch today may lead to isolated flooding of poorly drained areas. .DAYS TWO THROUGH SEVEN...Friday through Wednesday. Thunderstorms are possible Tuesday night through Wednesday. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated. && More information, along with other weather, hydrological and climate information can be found at http://weather.gov/ind
The national radar mosaic for the moment the first event began.
4 strong wind, 2 flood. Local standard time, as filed.
Areas of standing water noted along streets in Terre Haute.
Several trees were downed due to strong gradient winds. A semi was blown over on Interstate 74 near Ronald Reagan Parkway.
Tree was downed by strong gradient winds across 116th street. Soggy soil helped to bring the tree down at lower wind speeds.
Gusty gradient winds caused brief power interruptions and fallen tree limbs across Bloomington.
Several trees were downed due to strong gradient winds across the county. Heavy rains also led to several closed roads due to standing water along the roads.
There were eight roads in Hamilton county with reports of high water. One of which is 106th street. There also were several reports of trees and utility lines downed by strong gradient winds throughout the county.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Indiana in 2021Every state in 2021This day in weather historyWarnings in Indiana, March 2021
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: 938435, 938439, 938440, 938437, 938438, 938436.