Decoding Guide

Severe Weather Outlook Chart


This product depicts the area where the forecaster expects convection or severe convection to occur during the first 24-hour period. The product denotes the areas that have a marginal, slight, enhanced, moderate, or high risk of severe thunderstorms during the period. A text product accompanies this chart. The text offers a narrative discussion which explains the meteorological reasoning behind the forecast information depicted.


0700, 1500, and 1930 UTC

Data Sources:

Surface and Upper air soundings, Computer models


A severe thunderstorm is defined as a storm that has winds equal to or greater than 50 knots, hail equal to or greater than 3/4 inch in diameter, extreme turbulence, and/or a tornado/funnel cloud.

The areas forecast to have thunderstorms or severe thunderstorms are depicted to the right of the line.

Risk for severe thunderstorms:

MRGL Marginal risk - Includes severe storms of either limited organization and longevity, or very low coverage and marginal intensity.
SLGT Slight risk - Implies organized severe thunderstorms are expected, but usually in low coverage with varying levels of intensity.
ENH Enhanced risk - Depicts a greater concentration of organized severe thunderstorms with varying levels of intensity.
MDT Moderate risk - Indicates potential for widespread severe weather with several tornadoes and/or numerous severe thunderstorms, some of which may be intense.
HIGH High risk - Suggests a severe weather outbreak is expected from either numerous intense and long-track tornadoes, or a long-lived derecho system with hurricane-force wind gusts producing widespread damage.