Decoding Guide
Severe Weather Outlook Chart
Description:
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 slight, 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.
Issuance:
0700, 1500, and 1930 UTC
Data Sources:
Surface and Upper air soundings, Computer models
Depiction:
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:
| SLGT | Slight risk - 2 to 5 percent coverage |
| MDT | Moderate risk - 6 to 10 percent coverage |
| HIGH | High risk - greater than 10 percent coverage |
| APCHG | Approaching severe is used to denote a risk of a severe thunderstorm |