PredictWind Indicators for the Prediction of Severe Meteorological Phenomena

Recently, we have added CAPE and Gust Maps to help you predict severe weather phenomena and avoid these conditions.

CAPE

CAPE stands for Convective Available Potential Energy and represents the amount of fuel available for a developing storm. More specifically, it describes the instability of the atmosphere and provides an approximation of the strength of the updraft within a thunderstorm. Thus, CAPE is used by meteorological officials to understand the potential of thunderstorms and how powerful they could be if they materialize. The standard measure of energy is represented in Joules per kilogram. Meteorology experts may also express a high CAPE value using the term "high instability." When we talk about a highly unstable atmosphere, CAPE values are usually above 2500 J/kg, which would provide enough energy for strong updrafts and violent storms, if they were to develop.

Severe storms require high values of CAPE, and the higher the CAPE value, the more energy is available to promote storm growth. However, the CAPE variable is not a "magic number" that can predict the certainty of a thunderstorm. But if a thunderstorm develops and the CAPE value is high, then there will be a good chance of an "explosive storm." The following is a typical CAPE map in the Caribbean. The yellow/orange areas show high CAPE values.

The following table is a good guide for Storms/Lightning.

Gusts

Gusts are brief and sudden increases in wind speed. According to the U.S. weather observation practice, gusts are reported when the maximum wind speed reaches at least 16 knots, and the variation in wind speed between peaks and lulls is at least 9 knots. The duration of a gust is generally less than 20 seconds. All sailors know that it is the gust that can cause major damage and make it difficult to control the boat, and it is often more dangerous than a high average wind force. It is prudent to consult the gust map to check the maximum wind intensity that you may experience. A significant difference between the average wind force and gusts can be very dangerous, especially if you are unprepared. Therefore, we recommend that you check your meteorological route on gust maps to verify these situations. See a typical gust map of the North Atlantic. The dark red areas show wind gusts of over 35 knots. Gray areas indicate gusts of over 50 knots.

Rain Squalls

Rain squalls can also dramatically affect wind strength. These clouds "push" the air toward the surface, so if the cloud is directly against the wind, an increase in wind speed can be expected before it passes over and decreases afterward.

Check the latest Gust & CAPE Maps on the PredictWind website.