Right now
The most recent data we hold from NOAA arrived 6 minutes 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 18 June 2026 at 22:15 UTC. It is kept here as a record.
No stronger detection stands among the 65 recorded within 20 km of this point since 17 March 2026 — one other scored the same. Another comparable one was recorded here earlier the same day. 3 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Tornado Warning issued June 18 at 5:23PM EDT until June 18 at 6:15PM EDT by NWS Boston/Norton MA
Urban PEI: 853,884 within a heuristic 50 km radius; not unique people.
Nearby, since 17 March 2026
- August 8, 2026 · score 41 · 2.8 km
- July 29, 2026 · score 52 · 7.5 km
- June 7, 2026 · score 48 · 7.6 km
How we know
17 recorded sources include NOAA; independence is not established by this count.
Our own score for this event is 72 out of 100.
This is our versioned heuristic index, not source severity or a calibrated probability. Urban PEI does not count unique people.
Computed under scoring rules v1. Rows carrying other versions were judged by different rules and are not directly comparable.
Event Data
| Type | Severe Weather |
| Severity | Critical |
| Calamity Score (ours) | 72 / 100 |
| Legacy data-support index | 0.88/1 |
| Coordinates | 42.3240, -71.8640 |
| Nearest City | Holden (3 km) |
| Urban exposure index (PEI) | 853.9K within 50 km |
| Impact Tier | catastrophic |
| Timestamp | 2026-06-18T21:23:00.000Z |
| Source | https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.cb44f32923665e2bf19e357d471e9ea5c1455e77.001.1 |
Physical priority index · v1. Heuristic priority, not calibrated probability, predictive accuracy or damage. The legacy data-support index combines assigned source support and field availability. Urban PEI is distance-weighted and does not count unique people; zero does not establish that nobody is present. Model cards.
Source and revision timeline
Source: noaa. Occurrence: 2026-06-18T21:23:00.000Z.
First archived: 2026-06-18T21:26:42.823Z. Material modification: not recorded.
Retained revisions are prospective; earlier versions may be unavailable. No revision entry does not prove that a record never changed.
Score Breakdown
Technical Details
| Event | Tornado Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Middlesex, MA; Worcester, MA |
| Headline | Tornado Warning issued June 18 at 5:23PM EDT until June 18 at 6:15PM EDT by NWS Boston/Norton MA |
| Expires | 2026-06-18T18:15:00-04:00 |
| SenderName | NWS Boston/Norton MA |
| HasExactCoords | true |
| Iem TypeSummary | D |
| Iem City | Harrisville |
| Iem County | Cheshire |
| Iem State | NH |
| Iem Wfo | GYX |
| Iem Remark | Large tree down on Cheshire Rd. Time estimated from radar. |
| Google News RssFeed | weather |
| Google News SourceName | The Boston Globe |
| MergedSources | [{"id":"iem_D_42.790_-71.950_1781814180000","source":"iem","severity":"low","severityValue":25,"timestamp":1781814180000,"latitude":42.79,"longitude":-71.95},{"id":"iem_D_42.650_-72.610_1781812140000","source":"iem","severity":"low","severityValue":25,"timestamp":1781812140000,"latitude":42.65,"longitude":-72.61},{"id":"iem_D_42.690_-72.330_1781813400000","source":"iem","severity":"low","severityValue":25,"timestamp":1781813400000,"latitude":42.69,"longitude":-72.33},{"id":"iem_D_42.890_-72.270_1781811780000","source":"iem","severity":"low","severityValue":25,"timestamp":1781811780000,"latitude":42.89,"longitude":-72.27},{"id":"iem_D_42.600_-72.590_1781812200000","source":"iem","severity":"low","severityValue":25,"timestamp":1781812200000,"latitude":42.6,"longitude":-72.59},{"id":"iem_D_42.900_-71.780_1781814180000","source":"iem","severity":"low","severityValue":25,"timestamp":1781814180000,"latitude":42.9,"longitude":-71.78},{"id":"iem_D_42.600_-72.600_1781812200000","source":"iem","severity":"low","severityValue":25,"timestamp":1781812200000,"latitude":42.6,"longitude":-72.6},{"id":"iem_D_42.580_-72.440_1781814000000","source":"iem","severity":"low","severityValue":25,"timestamp":1781814000000,"latitude":42.58,"longitude":-72.44},{"id":"iem_D_42.940_-72.090_1781811900000","source":"iem","severity":"low","severityValue":25,"timestamp":1781811900000,"latitude":42.94,"longitude":-72.09},{"id":"gnews_weather_494946_140","source":"google_news","severity":"medium","severityValue":40,"timestamp":1781806545000,"latitude":42.36,"longitude":-71.06},{"id":"gnews_weather_494944_144","source":"google_news","severity":"medium","severityValue":40,"timestamp":1781800384000,"latitude":42.36,"longitude":-71.06},{"id":"gnews_weather_494947_147","source":"google_news","severity":"medium","severityValue":40,"timestamp":1781810768000,"latitude":42.36,"longitude":-71.06},{"id":"gnews_weather_494943_148","source":"google_news","severity":"medium","severityValue":40,"timestamp":1781796271000,"latitude":42.36,"longitude":-71.06},{"id":"gnews_weather_494946_161","source":"google_news","severity":"medium","severityValue":40,"timestamp":1781806310000,"latitude":42.36,"longitude":-71.06},{"id":"gnews_weather_494946_164","source":"google_news","severity":"medium","severityValue":40,"timestamp":1781809095000,"latitude":42.36,"longitude":-71.06},{"id":"gnews_weather_494948_166","source":"google_news","severity":"medium","severityValue":40,"timestamp":1781814941000,"latitude":42.36,"longitude":-71.06}] |
Safety Information
If a tornado warning is issued: go to a basement or an interior room on the lowest floor, away from windows. A vehicle and a mobile home are not shelter. Cover your head and neck. Wait for the official all-clear before going outside, and watch for downed power lines and gas leaks afterwards.
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.
Review the area, threshold and delivery channel in your account.
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