Flash Flood: how HazardNet classifies and scores it
Short-duration, high-intensity flooding: the burst case of the rainfall proxy.
How the model arrives at this class
This hazard's inputs are research-private. On the committed snapshot the two classes are almost never both plausible for the same unit, and the physics track cannot arbitrate between them.
Same softmax caveat as Flood: uncalibrated, and published with that label.
Advisory levels follow the published alert policy and the escalation boundaries of the responsible authorities; nothing here overrides them.
The independent physics cross-check
Identical to Flood in this implementation. The intensity term is what makes a burst score higher than a drizzle of the same total, but nothing in the proxy separates a flash flood from a slow one.
Drivers: precipitation accumulated over the horizon (P_total) · wettest 24 hours in that horizon (P_peak).
- Expression: 0.5*clip(P_total/300) + 0.5*clip(P_peak/100)
- That expression is executed against the pipeline’s own implementation by the content tests in CI: this page cannot silently describe a formula the pipeline no longer runs.
What the current run says about Flash Flood
In the run this deployment ships (prediction date 2026-11-02), 50 district trajectories are classified as Flash Flood across the continuous 15-day window (Days 1 to 15).
Highest model severity: Bagerhat (0.30, Days 1 to 15), Barguna (0.30, Days 1 to 15), Barishal (0.30, Days 1 to 15), Bhola (0.30, Days 1 to 15), Bogra (0.30, Days 1 to 15).
These are classifications from the current run, not a forecast of impact. Advisory levels follow the published escalation gate alongside official Bangladesh authorities.
Season and geography
Typical season: March–May (pre-monsoon convection) and June–September. This describes when the hazard is climatologically plausible, not when this run flags it.
What this class cannot tell you
- No terrain or drainage: catchments, slope and urban surfaces are absent, which is exactly what decides whether a burst becomes a flash flood.
- Haor and hill-district flash floods are driven by upstream rainfall outside the district boundary; the drivers are district-aggregated.
- A 24-hour peak inside a 15-day horizon is a coarse instrument for an event that lasts hours.
- Confidence is published as an uncalibrated model score; no calibration accuracy is claimed.
Inputs behind it
Published assessments and official bulletins are the record; this site reports what they name.
- published forecast records
Questions and answers
Is a high Flash Flood severity a prediction of damage?
No. The severity index is the model's continuous score for how strongly the drivers resemble this class, on a 0.00–1.00 scale. It is not a probability, not a percentage, and it does not model exposure. The physics cross-check is a second, independent estimate; where the two diverge, both numbers are shown rather than averaged.
Why is the confidence not a probability of Flash Flood?
The published confidence is the model's own confidence over its eight classes, labelled uncalibrated_model_confidence in the data. It says how certain the classifier is about the class it picked, not how often that class actually materialises. No calibration has been fitted yet, which is also why nothing above the WATCH level can be published automatically.
Which districts does this page cover?
The district pages cover all 64 districts. This page summarises the districts the current run covers: a run can be partial, and the coverage stamp on the snapshot says exactly how partial, which the status page reports.
HazardNet is not an official warning service. Official warnings come from BMD and FFWC. In an emergency call 999.
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