An upper level low is spinning over the Southwest this morning. Attached to a cold front, that stretches from El Paso to Chicago, the storm is pulling in moisture from the Gulf of California, producing mountain snows and valley rains across the Four Corners region; the higher elevations of West Texas can also expect snow from this storm.
Forecast to move eastward and then northeastward over the coming days, this low pressure will begin to tap Gulf of Mexico and Atlantic moisture and drop significant rain across almost all of the East, from the Gulf Coast to New England. Depending upon the relative positions of the cold front and the central low, snow accumulation could be significant in the Northern Appalachians.
Such storms systems, which typically move from west to east across North America, illustrate the dynamics of our weather, combining the effects of wind direction, lift (from both the low and the topography), air temperature and atmospheric moisture; the latter develops as air moves over the ocean or Great Lakes. Contrary to a common perception, these storms are not just a mass of clouds that drop their precipitation as they move across the country; rather, the central low is a pump, constantly mixing the essential ingredients, mentioned above, and interacting with the surface features of our planet.
