Cold Wave: how HazardNet classifies and scores it
How far the minimum falls below 16 °C, plus persistence.
How the model arrives at this class
Classified from the same drivers; the districts that score highest are the ones where the minimum genuinely falls, not an a-priori cold-region list.
Uncalibrated softmax. Fog, the mechanism that makes a Bangladesh cold wave dangerous, is not a driver.
Advisory levels follow the published alert policy and the escalation boundaries of the responsible authorities; nothing here overrides them.
The independent physics cross-check
16 °C is the reference minimum at which the temperature term starts scoring; it is a formula constant, not a met-service threshold.
Drivers: minimum temperature in the horizon (T_min, °C) · length of the horizon (days).
- Expression: 0.7*clip((16-T_min)/10) + 0.3*clip(duration/5)
- 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 Cold Wave
The run this deployment ships (prediction date 2026-11-02) classifies no district trajectory as Cold Wave across Days 1 to 15. An absence of cold wave in one run is not a statement that the hazard cannot occur this season.
Season and geography
Typical season: December–February, concentrated in the north and north-west. This describes when the hazard is climatologically plausible, not when this run flags it.
What this class cannot tell you
- No fog, no wind chill, no humidity: a dry 9 °C night and a foggy 9 °C night score the same.
- BMD's own cold-wave criteria (which are station-based and use consecutive-day rules) are not what this proxy implements; the two can disagree, and this page says so rather than implying equivalence.
- 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 Cold Wave 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 Cold Wave?
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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