SPLIT-FRONTAL TYPE

A situation where the vertically thick/cold-top upper cloud (usually producing the significant rain) has moved well forward, and moves notably faster than the classically analysed surface front (wind shift, dew point drop etc.). With dry air over-running the rearward feature, the precipitation on the surface cold front is often light & 'drizzly'. Comparison of IR imagery (showing the sharp rearward boundary of the upper front), with the VIS imagery (showing the break from stratiform to broken, or cumuliform cloud structures), will identify such features very well. Sometimes an upper cold front will be analysed on Bracknell charts when such a 'split' is well-marked.