GribStream

NOAA SPC HREF 4-hour Calibrated Tornado Probability

GribStream Code: spctor4hr

Description

SPC HREF calibrated tornado probability is a specialized convective-hazard field from the Storm Prediction Center post-processing suite. It expresses tornado risk over four-hour windows, which is useful for operational situational awareness before warnings exist and after broad outlook categories need to be localized.

The calibrated tornado method combines storm-scale HREF signals, including updraft-helicity information, with a larger-scale severe environment. SPC's calibration framework relates those paired signals to historical report frequency near each grid point and time window. That makes the product a direct probability layer for decision support rather than a raw model ingredient.

Use this dataset for severe-weather dashboards, emergency-management triage, operations centers, utility and transportation risk screening, and applications that need a machine-queryable tornado-risk signal. It should be interpreted with SPC Hail 4h, SPC Wind 4h, HRRR, and official SPC outlook and warning products.

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