60/100

Moderate evidence

Trace: a gain and a problemPublished recordClimateThe Trace

Progress toward forecasting excessive rainfall with random forests based on a deterministic convection-allowing model

Truvace record
TRV-2026-2655raw data (JSON)
Version
v1Published
First published
Evidence type
Observational study
Sources
1 sourcePeer-reviewed
sha256
7d750c512561…check it

Abstract Machine learning applied to high-resolution numerical weather prediction forecasts is gaining popularity for prediction of high-impact weather events, but questions remain on how to design such systems. Building off prior work, we describe sensitivity experiments using a random forest (RF) system for excessive rainfall prediction using the deterministic High-Resolution Rapid Refresh (HRRR). We find that applying an RF trained on HRRRv3 to daily forecasts from HRRRv4 does not significantly degrade result…

55Gain side

How the two sides scoreClose call

57Problem side

The gain

In sensitivity experiments on a random forest excessive rainfall system built on HRRR forecasts, using all nearby gridpoints and averaging predictors across several model initializations significantly improved forecasts, especially for small-scale rainfall maxima.

The problem

In more than four years of real-time forecasts, random forests based on HRRR rainfall forecasts underperformed a Global Ensemble Forecast System-based random forest, and neither matched the operational day-one excessive rainfall outlook; the HRRR version also underpredicted events.

A fixed formula sets both scores from the evidence and its sources. Reader votes don’t move them.

What the scores mean

G is the gain side, out of 100. It goes up when the gain is specific, when it measurably helped people and when the sources behind it are strong.

P is the problem side, out of 100. It goes up when the problem is specific, when it measurably hurt people and when the sources behind it are strong.

What this doesn’t fix

The HRRR-based system showed an underprediction bias, partly because verification used a more comprehensive excessive rainfall dataset than the one used for training.

Sources

1 on file
  1. Peer-reviewed2026-10-26

Cite this record

v1

Truvace Impact Record TRV-2026-2655, v1: “Progress toward forecasting excessive rainfall with random forests based on a deterministic convection-allowing model.” Truvace, 2026-11-12. /record/TRV-2026-2655 (accessed on the day you copy it). sha256 7d750c512561566b…

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