Thank you to everyone for your reports! Please send these in any severe weather situations! They do not go unnoticed & are vital to mapping things out & assisting the National Weather Service in their warning process!
In a swath of 30-50 mph t'storm wind gusts (with a few small sporadic pulses of 50-60 mph gusts) in the heart of the viewing area, two well-defined macrobursts struck the area on June 5, 2019.
60 mph wind damage was found near Shadeland with hail damage to cars & roofs indicating maximum size of 1-1.75" hailstones (quarter to golfball size).
Another 60 mph core was found near & at Linden.
Macroburst is a type of downburst.
There are wet & dry downbursts. This was a wet one with flooding rainfall.
Here are the differences (according to NOAA National Severe Storms Laboratory or NSSL):
A macroburst is an outward burst of strong winds at or near the surface with horizontal dimensions larger than 4 km (2.5 mi) and occurs when a strong downdraft reaches the surface. To visualize this process, imagine the way water comes out of a faucet and hits the bottom of a sink. The column of water is the downdraft and the outward spray at the bottom of the sink is the macroburst. Macroburst winds may begin over a smaller area and then spread out over a wider area, sometimes producing damage similar to a tornado. Although usually associated with thunderstorms, macrobursts can occur with showers too weak to produce thunder.
A microburst is a small concentrated downburst that produces an outward burst of strong winds at or near the surface. Microbursts are small — less than 4 km across — and short-lived, lasting only five to 10 minutes, with maximum windspeeds sometimes exceeding 100 mph. There are two kinds of microbursts: wet and dry. A wet microburst is accompanied by heavy precipitation at the surface. Dry microbursts, common in places like the high plains and the intermountain west, occur with little or no precipitation reaching the ground.
1. MACROBURST #1: SOUTHSIDE OF LAFAYETTE
MAXIMUM WIND: 80 MPH (65-80 MPH)
Damage from the southside macroburst was very similar to the July 17, 2010 downburst that struck West Lafayette (just a hair weaker at its greatest damage area), specifically near University Farms with a 74.6 mph wind gust measured at WLFI with heavy tree damage. 70-80 mph damage was common in this particular downburst with peak of 82 mph in an area that saw tree lamps bent & metal garage doors bent & blown inward.
Extensive tree & powerline damage occurred with the June 5 event. At least 3 cars were damaged or totals. Roof damage was observed on 6 quick looks of homes. Some siding & metal was stripped off a few homes & outbuildings. Several homes were damaged by fallen trees or large limbs.
The extensive planting of Silver Maple contributed to the heavy tree damage & exceptional amount of tree debri in the macroburst. This wood tends to be brittle on these trees & the tree ages date back to the time these neighorhoods were contructed in the 1950s to 1970s. That species saw the worst damage with entire crowns completely ripped apart & de-branched, only leaving stubs. Bradford Pears greater than 10 years of age were also heavily damaged or completely snapped off.
However, many old-growth Bur, White, Chinkapin, Swamp White & Shingle Oaks in the area saw extensive damage. A large Bur Oak & Shingle Oak were snapped at the base. A stately Shingle Oak on S 100 E was snapped at the base, but had decay in the heart of the trunk all the way to the trees' base. Using the Growth Factor equation based on diameter in accordance to species, tree age varied on these solitary specimens to groups of 110-200 years of age. Owing to strength of the wind, especially in the core, even small ornamental trees were ripped up, snapped, or otherwise uprooted. Various Red Maple cultivars, Linden spp, London Planetree, Freeman's Maple, Blue, Black & Norway Spruce were damage or toppled. Eastern White Pines were snapped.
Fences were blown down, garage doors damaged, trampolines tossed & crumpled, playsets thrown & rolled & privacy fence doors were completely bent backward. A flagpole was completely bent in half.
Horizontal vortex rings or rolls were evident in the macroburst, as certain uncommon tree species limbs & shingles from certain homes were thrown back in the opposite direction of the dominant wind.
The west side of the down burst showed debri blow largely north-northeast to south-southwest, while the east side was dominated by a northwest wind pattern.
The edge of it was sharp. The large oaks of the Central Catholic Grove off South 9th were spared any damage. However, just 500' away, there was quite a bit of damage.
Concord & Brady area saw evidence of being right within the 70-80 mph core, but a properly-sited anemometer near 52 & Veteran's Memorial measured a maximum gust of 53 mph. This sharp edge is typical of downbursts. The properly-placed Benjamin Crossing anemometer was in error that day with it not measuring properly. It's data was excluded. A sensor at Miami Elementary measured a 60 mph gust with a sustained wind of 48 mph. Comparing past data from this sensor, it shows wind to be around 8-10 mph less that what it actually is. This is due to the siting of the anemometer. The gust was probably more like 70 mph.
Rainfall was +4" per hour in the storm.
This London Planetree was bent by the downburst winds. It is unclear whether there is roof damage on the other side of the home as the photographer did not show that part.
There are several reports of limbs, some large, being impaled into the ground. Some were impaled as much as a foot deep.
This scud on the edge of the shelf cloud led many to think it was a tornado that caused the damage. This resembled a tornado shape, but did not have the structure of a tornado, was on the front of the storm & debri was not being picked up by it. Also, radar shows no evidence of rotation.
This cloud feature was most pronounced as the storm approached the southside of Lafayette.
This image was taken at West Lafayette.
Damage shows strong evidence of horizontal vortex rings in the downburst. Again, species of certain trees' limbs were actually flipped backward & tossed the opposite direction. This could be mistaken for tornado damage.
I tracked some limbs that were flung backward 1.5 blocks in the opposite direction of the downburst winds due to the horizontal rolls!
These are NOAA images below, including photos of downburst & horizontal vortex rings.
2. MACROBURST #2
MAXIMUM WIND SPEED: 80 MPH (65-80 MPH)
Numerous trees were damaged or snapped in tree lines, fencerows, woods & various farmsteads in this macroburst (with torrential rainfall). Several trees were large +100-year old Bur & Swamp White Oaks snapped or uprooted. Power poles were snapped & some minor damage occurred to a couple of farm buildings where 80 mph gusts most likely occurred. Some large limbs were impaled deeply into mud in some fields.
Gusts of 70 & 73 mph were measured northwest of Gladens Corner on 28.
3. WESTERN TIPPCANOE GUSTNADO
Southwest of Shadeland, on the Wea Plains, a gustnado occurred on the edge of the strong winds from the storm.
NOAA NSSL states: Gustnadoes, [are] whirls of dust or debris at or near the ground with no condensation funnel, which form along the gust front of a storm.
I have seen gustnadoes flip & destroy mobile homes before (occurred in southern Indiana years ago) & flip & crumble irrigation pivots.
Josiah Maas caught images of the shelf cloud or leading edge of strong winds & the gustnado.
Josiah Maas shot of the gustnado:
- Local Weather History: Macrobursts, Gustnado & Scud of June 5, 2019
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