WX MODEL 4: Cut-off Low


A cut-off low is a deep low pressure system that drifts, stalls or moves slowly due to being too far from a jet stream current that would help move it also. A cut-off low can persist at a location for several days until the system disintegrates or the flow pattern finally changes so that the low pressure can move out. The cut-off low can cause the weather to repeat day after day. Under the low there can be a persistence of cloudy and rainy weather.

The image below shows a cut-off low at 300-mb over Mexico. Note the system is cut-off from the polar jet stream and the tropical winds surrounding it are too weak to move it along. These systems can persist for days. Forecasting these systems is important since they can bring the same weather for several days. The circulation pattern around the cut-off low (several height contours spinning the air in circles) helps keep it in place.