Evening US - Canada Surface Map

Map plotted by Digital Atmosphere software from WeatherGraphics. com

Pressure patterns determine the wind direction and speed. In this post we will look at how a large area of high pressure and areas of low pressure are controlling the wind patterns over the U.S. and Canada. The air converges into low pressure centers and diverges away from high pressure centers. Air flows counterclockwise around low pressure in the Northern Hemisphere and clockwise out of high pressure centers. 

Large surface high pressure centered over the Northern Plains into Canada and south to Texas this evening. Temperatures in Northern Canada remain below zero with readings in the 30s across much of southern Canada into the U.S. east of the Rockies. The steamline map below, which is a snapshot of the wind direction shows north and northwest winds from central Canada to New England and from the Northern Plains south to the Gulf of Mexico. Light and variable winds extend from the West Coast to the Intermountain region, northern Rockies into Canada. Easterly winds are reported from western Canada toward the Gulf of Alaska. Air is flowing  out of the high pressure westward and to the east and southeast. The Polar Front extends across the southern United States and Mexico and the Arctic Front stretches across northern Canada. Notice the northeast winds from the North Atlantic into eastern Canada. This flow is wrapping around a large low pressure center in the North Atlantic. Clouds and precipitation are found near the fronts, bodies of water, and in the central and eastern United States. 

STREAMLINES PLOTTED BY dIGITAL aTMOSPHERE SOFTWARE AVAILABLE AT wEATHERgRAPHICS.COM