Rainy Saturday I (warm front, and low pressure system

A rainy Saturday. A good day to stay inside and work on your weather studies.

The map at left for 15Z (11 AM) shows us why. We have a low pressure system currently situated just north of the Great Lakes and moving in from the west. A warm front extends eastward and across New England. This is bringing in steady rain of moderate intensity extending over a broad area from New York State to Atlantic Canada. This type of rain is called stratiform precipitation because it falls from a low-level, flat layer of stratus cloud. Rain like this usually lasts about a day because it is so widespread. It takes time for a system this large to move through an area.

As studies in Chapter 1, the wind circulation around this low (red arrows) is counterclockwise and inward. East of the low (i.e. New England and eastern Canada), this circulation causes southerly winds (FROM the south) that bring in a moist tropical air mass from the south behind the warm front. You'll notice that even though it is cloudy outside, it is still pretty warm.

You can find more maps like this at the NWS-HPC website.