Surface Map, January 12, 1996 Storm

The 500 Mb chart of this storm indicated that surface lows should occur just north of the Great Lakes and over the southeastern United States; this view of surface pressure and precipitation conditions show that this is so. Notice that, unlike the 500 Mb chart, the two low pressure cells are enclosed by isobars (shown in narrow white lines.) Winds are blowing into the centers of these cells in a counter-clockwise fashion, cutting the isobars at an angle instead of parallel as they do on the 500 Mb chart.

Notice the intensity of the precipitation associated with the two low pressure cells. There is more associated with the southeastern cell because it has relatively warm ocean water to draw from. The approximate position of the cold front associated with the SE cell is indicated by the heavy, pale blue line; there is not much of a warm front associated with this cell. Approximate locations of the warm (pale red) and cold (pale blue) fronts associated with the low above the Great Lakes have been added to this map. White arrows showing the direction of winds about this low have also been added.

The area of heavy precipitation in southwestern Canada is due to relatively warm, most air being drawn off of the ocean and forced to higher elevations as it travels onto the continent. At the time of this map, the western states would be enjoying relatively mild temperatures and clear skies, while the eastern states would be suffering from unseasonably cold temperatures, clouds, and heavy precipitation.