Never Trust A Warm Front--Heavy Rain Again!

"Never Trust A Warm Front"!

These words of Dick Goddard and Andre Bernier have also been echoed by myself over the years after forecasting many heavy rain and nighttime severe weather events in northern Ohio, West Virginia and St. Louis going back more than 20 years.

Why are warm fronts so tricky? The dynamics of a warm front are completely different than a cold front. The cross section of each tell the story on how the air is stacked above each front. A more detailed technical discussion is located on this site with a nice powerpoint download.

Cold Front Cross Section

Warm Front Cross Section

Clusters of "blob-like" storms tend to develop along warm fronts. These clusters start vie for position and dominance as they move into areas more conducive for sustainability. One cluster robs another of energy/moisture in order to sustain itself while other might shrink.  Yet several clusters might merge together to form one super cluster as was the case on Monday, May 12th. Radar loop is over approx 40 minutes from 8PM to 8:40PM over northern Ohio.

The combination of a moisture-laden atmosphere, rapidly rising and divergent (separating air) at the top of the storms along with hyper-local changes as the storms evolve over a small area make these clusters very difficult to predict more than a few hours in advance in many instances. Their non-linear nature makes it very difficult to determine an accurate track and duration.  They can become especially powerful during the overnight/predawn hours. The high resolution NAM below (future radar) shows several clusters overnight Tuesday into Wednesday more than 24 hours in advance. Their movement is usually west to east or northwest to southeast along the warm frontal boundary.

Compare that to what a "typical" line of storms looks like along a powerful cold front.

So watch the radar below tonight and early Wednesday for the "cluster-type" setup. These clusters can accelerate and morph into hail producing, high wind storms easily reach severe limits.

I GUARANTEE THAT SOME LOCATIONS WILL RECEIVE MORE THAN 1" OF RAINFALL ON WEDNESDAY!