That Cutoff Low Part Deux!

Courtesy weather.cod.edu

The satellite image above is what we call a water vapor image.  It literally shows you the humidity in the middle atmosphere. Darker shades show drier air and you can usually assume that means the air is sinking there. Brighter shades indicate greater amounts of humidity and generally rising air.

If you look closely you can see the low pressure system that is forming and not every place in theow has rising air.

As the low wobbles around over the Tristate this weekend when you encounter an area where the air is rising above your location clouds will increase and there is a chance for a shower.  Sinking air means that the sky may clear a bit and rain will end.

The animation below compares the cutoff low to a wagon wheel.  The spokes represent areas with lift and in between the spokes the air is sinking.  When a spoke moves over you showers develop because the air is rising.  This creates periods of rain and cloud cover interspersed with some clearing and dry weather.

Now if the low wobbles, or the spokes are curved or winds in the atmosphere change the shape of the low the pattern becomes complitaced and harder to forecast.

Take a look at the video for more.