The Shark Fin

A feature that I look for on temperature forecast model is what I call the "Shark Fin".    No one that I know of but me, calls this feature this.  On the Forecast model below, look where the white color meets the green - right where the number 132 is.   There are actually 2 shark fin features on this model. One off the southern BC coast and one just entering the Aleutian Islands.

This air tempeature transition is the leading edge of a warm front followed by a cold front - it looks like a sharks fin to me.   You can find this feature on the GFS 850mb 36k model as well.

This is an important feature to keep an eye on when watching freezing level spikes. How sharp the fin feature is, and how it stays in tact as it approaches, gives a good sense of how drastic a temperature spike will be.