WINTER STORMS OVER THE BORDERLAND
While many people escape to the southwest during  the winter because of its mild, dry and sunny climate it must be remembered southern New Mexico and far western Texas can experience periods of stormy  weather from late autumn into early spring. Depending on the weather or circulation pattern, inclement cool-season weather may take the form of snow, ice or winds.

Winter storms are usually associated with areas of low pressure known as cyclones. Under normal circumstances the winds across southern New Mexico and far western Texas blow from west to east during the cool season with the high mountains over California, Arizona and northwestern Mexico
blocking any low level moisture heading our way.     		picture of heavy snowfall for El Paso
Winter storms can and do occasionally strike the southwest. Almost two feet of snow fell in the El Paso area December 13-14, 1987 literally paralyzing the city.
This explains why the region is so dry from late September through early June. However any time from November through early April our mild dry weather can transform into cold, snowy or even icy conditions within hours if a cyclone develops, intensifies and moves across certain areas of the southwest.

Cyclones can  be very complex but one important characteristic is the winds flow counterclockwise or cyclonicly around the center of low pressure.  As a result the optimal situation for snow across southern New Mexico and far western Texas is the development of a strong cyclone or low pressure center at the surface over southern Arizona or northwestern Mexico with a subsequent eastward or southeastward movement  across northern Mexico south of the New Mexico border. A storm evolving and tracking in this manner can pull cold Artic air from Canada as far south as Mexico at the surface causing temperatures to fall below freezing. Of equal importance, the cyclonic flow around the low will also pull moist air from the Gulf of Mexico northward where it is forced up and over the colder air at
covering the surface . This process is favorable for 
snow or less frequently, ice. (continued on page 4)

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 weather map

Optimal conditions for snow include the movement of a strong surface low or cyclone ( L ) across northern Mexico where it can pull cold Arctic air   into New Mexico and western Texas at low levels while pulling moisture from the Gulf of Mexico and the Gulf of California or the Pacific aloft.