Calamity
MediumSevere WeatherCalamity Score: 43

Severe Weather in United States

Big HornUnited StatesNOAA

Right now

The most recent data we hold from NOAA arrived 1 minute ago, and this point is not in it. We record detections, not passes: an absence is not proof that nothing is there.

Nothing else has been detected within 20 km in the last 24 hours.

This alert expired on 27 June 2026 at 21:47 UTC. It is kept here as a record.

No stronger detection stands among the 8 recorded within 20 km of this point since 27 June 2026 — 3 others scored the same. Another comparable one was recorded here earlier the same day. 2 more were recorded here in the fortnight before it.

What the source measured

NOAA reported: Flash Flood Warning issued June 27 at 3:37PM MDT until June 27 at 3:45PM MDT by NWS Billings MT

An estimated 117,116 people live within 50 km of this point.

Nearby, since 27 June 2026

How we know

Confirmed by 4 independent sources, including NOAA.

Our own score for this event is 43 out of 100, at 87 % confidence.

The score is ours, computed from intensity, exposed population and local history — not the source’s.

Computed under scoring rules v1. Rows carrying other versions were judged by different rules and are not directly comparable.

Event Data

TypeSevere Weather
SeverityMedium
Calamity Score (ours)43 / 100
Our confidence87%
Coordinates45.5958, -107.9614
Nearest CityBillings (47 km)
Population Exposed117.1K within 50 km
Impact Tiersignificant
Timestamp2026-06-27T21:37:00.000Z
Sourcehttps://api.weather.gov/alerts/merged_Flash Flood Warning_noaa_urn:oid:2.49.0.1.840.0.950603e070c91c5d3554e23e6bd07615

Score Breakdown

35
intensity
70
population
0
cascading
80
historical

Technical Details

EventFlash Flood Warning
UrgencyImmediate
CertaintyLikely
AreaDescStillwater, MT; Yellowstone, MT; Big Horn, MT and 1 more areas
HeadlineFlash Flood Warning issued June 27 at 3:37PM MDT until June 27 at 3:45PM MDT by NWS Billings MT
Expires2026-06-27T15:47:00-06:00
SenderNameNWS Billings MT
HasExactCoordstrue
MergedCount4
MergedIds["noaa_urn:oid:2.49.0.1.840.0.950603e070c91c5d3554e23e6bd0761582ec85fd.001.1","noaa_urn:oid:2.49.0.1.840.0.5a1f6937d5a56f45cb9e570115c1a3fc06f80748.001.1","noaa_urn:oid:2.49.0.1.840.0.4c0b22b824d5e2fa4e3eda44dafbd6adf5fe0fec.001.1","noaa_urn:oid:2.49.0.1.840.0.6a3c3f269aa4fc2aa610e083110096b2bbeaebd2.001.1"]
Iem TypeSummaryH
Iem Magnitude0.88
Iem UnitInch
Iem CityLaurel
Iem CountyYellowstone
Iem StateMT
Iem WfoBYZ
Iem RemarkDime to nickel sized hail. Rainfall filling curbs.
MergedSources[{"id":"iem_H_45.750_-108.570_1782590400000","source":"iem","severity":"low","severityValue":25,"timestamp":1782590400000,"latitude":45.75,"longitude":-108.57},{"id":"iem_H_45.680_-108.770_1782590400000","source":"iem","severity":"low","severityValue":25,"timestamp":1782590400000,"latitude":45.68,"longitude":-108.77},{"id":"iem_H_45.680_-108.780_1782588900000","source":"iem","severity":"low","severityValue":25,"timestamp":1782588900000,"latitude":45.68,"longitude":-108.78}]

Safety Information

During flooding: never walk, swim, or drive through floodwaters. Six inches of moving water can knock you down, and one foot of water can sweep away a vehicle. Move to higher ground if waters rise. After flooding, avoid contact with floodwater which may contain sewage, chemicals, or debris. Follow local emergency service guidance.

Series begins 8 March 2026. Comparisons refer to that period only. Collection gap: 14-26 August 2026.

This data is aggregated algorithmically from scientific sources. Not a replacement for official emergency warnings.

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