Original title: Baseline Climatology of Tornadoes and Waterspouts in the Philippine Archipelago
Generich H. Capuli · September 2026
Most storm warning tools were built using data from places far from the equator. Because of this, scientists know little about tropical tornadoes. To solve this, researchers gathered historical reports of tornadoes and waterspouts across the Philippines. They matched each event to atmospheric data to see how tropical storms form. They found that storm energy is extremely high, beating typical levels seen in the Great Plains. However, winds higher up change very little. Instead, the spin needed to trigger a tornado happens almost entirely in the lowest kilometer near the ground. Most of this near-surface spin flows in the direction of the wind. Because standard forecasting tools look for deep wind changes, they underestimate these tropical events. Forecasters need locally adjusted thresholds to detect these severe storms correctly.
Imagine you are baking a cake. Normally you need both a hot oven and a good mixing technique to make it rise evenly. But suppose you have a very hot oven, yet you barely stir the batter. The cake might still rise unevenly or collapse. In this paper, the researchers found that Philippine tornadoes form in very hot, humid air (high CAPE) but with almost no wind shear (weak mixing), so the usual recipe for tornadoes from the US doesn't apply.
Weather forecasters in the Philippines and other tropical regions cannot rely on US-based tornado prediction tools. These tools assume both high heat and strong wind shear, but Philippine tornadoes occur with weak shear. Without locally adjusted thresholds, warnings may miss real threats or give false alarms, putting lives and property at risk.
The abstract doesn't explicitly state limitations, but it notes that composite indices underestimate even as tornadoes recur, and that locally rescaled thresholds are required, implying the current indices are inadequate. The study is based on historical reports and ERA5 reanalysis, which may have uncertainties in data quality and spatial resolution.
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Baseline Climatology of Tornadoes and Waterspouts in the Philippine Archipelago — Generich H. Capuli
Abstract licence: CC0
Explanation generated by Synthesis from the abstract — it is not the original paper. This is a preprint, so it hasn't necessarily been peer reviewed.