Thunderstorm symbol

How to read it

In the WMO’s present weather table, as reproduced by NOAA’s JetStream school, the symbol on its own is code 17: thunder heard, but no precipitation at the station. Codes 95 to 99 add what is falling: a dot for rain, an asterisk for snow, a triangle for hail. JetStream’s code 95 is a slight or moderate thunderstorm with rain or snow, and 96 a slight or moderate thunderstorm with hail. The University of British Columbia’s course chart gives the same meanings from the WMO code, up to a heavy thunderstorm with hail.

Also searched as: hail symbol, lightning arrow symbol, R with an arrow on a weather map, thunderstorm weather symbol, thunderstorm with hail.

Hail

Hail on a station plot is a solid triangle. Over the thunderstorm symbol it means a thunderstorm with hail; over the open triangle of a shower it means a shower of hail “not associated with thunder”, in JetStream’s words. ! wx-chart-thunderstorm-rain | Thunderstorm with rain | A dot above the thunderstorm symbol. ! wx-chart-thunderstorm-hail | Thunderstorm with hail | A small triangle above it. ! wx-chart-hail-shower | Hail shower | A solid triangle over an open one pointing down.

Thunderstorm in the last hour

JetStream’s table also has symbols for a thunderstorm during the preceding hour but not at the time of observation, with rain or snow falling now.