Cloudburst Explained: Causes, Intensity & Safety
A cloudburst is an extremely intense, short-duration rain event, often defined as around ≥ 100 mm in ~1 hour over a small area (roughly tens of square kilometers). Because so much water falls so fast, cloudbursts can trigger flash floods, landslides, and severe urban inundation.
How it forms (in simple terms): warm, moisture-laden air rises rapidly, forming towering cumulonimbus clouds. Orographic lift (mountains) or stalled storm cells can focus the downpour over one spot. When the cloud’s updrafts weaken and heavy raindrops fall together, the storm can unload a torrent in minutes.
Track real-time rain rates and forecasts on Weather Pulse Now to spot dangerous spikes early.
| 🌧️ 1‑Hour Rainfall (mm) | Intensity | Likely Impact |
|---|---|---|
| < 25 mm | Heavy | Ponding on roads, slick driving |
| 25 – 50 mm | Very Heavy | Street flooding in low areas, drainage stress |
| 50 – 99 mm | Severe Downpour | Rapid flooding of underpasses and basements |
| ≥ 100 mm | Cloudburst Threshold (commonly used) | Flash flooding likely, streams rise quickly |
| ≥ 150 mm | Extreme Cloudburst | Life‑threatening flooding, landslide risk (hilly terrain) |
| ⛈️ Phenomenon | What it is | How it differs |
|---|---|---|
| Heavy Rain | High rain rate over minutes to hours | May be widespread; not always extreme enough for flash floods |
| Thunderstorm | Convective storm with thunder/lightning | Can produce hail, wind, or heavy rain; not all cause cloudbursts |
| Cloudburst | Exceptionally intense, localized rain (often ≥100 mm/hr) | Short-lived but concentrated; flash floods are common |
| 🔎 Early Signs | What it may indicate |
|---|---|
| Stationary dark cumulonimbus over hills/valleys | Storm cell is anchored → prolonged dumping over one spot |
| Rapid rise in humidity; dew point near air temperature | Very moist air ready for intense convection |
| “Training” echoes on radar (cells moving along same track) | Back‑to‑back downpours over the same location |
| Short‑range forecast spikes in mm/hr | Nowcasts flag flash‑flood potential in next 0–3 hours |
Safety checklist (quick)
- Avoid underpasses, basements, and low‑lying roads. Turn around, don’t drive into water.
- Move to higher ground if water rises; never walk through fast‑moving floodwater.
- In hilly areas, watch for landslide signs (cracks, rumbling, tilting poles/trees).
- Keep phones charged; have a flashlight and a small go‑bag ready in monsoon season.
By watching mm/hr rain rates, short‑term radar loops, and localized alerts on Weather Pulse Now, you can spot cloudburst risk early and act quickly.