1. Fronts (Frontera) and Low

2. Weather in the mid-west is constantly changing. Changes in weather are caused by fronts Front (Frontera)– the boundary that separates opposing air masses

3. Fronts can range in width from 200 meters to 200 kilometers

4. Fronts can affect weather patterns in areas hundreds of kilometers wide

5. Fronts are most common at mid- latitudes Cold air from the north and warm air from the south meet in the mid-latitudes

6. Fronts are wedge-shaped The steeper the wedge, the more severe the weather

7. Fronts usually produce precipitation Cool air rises and condenses and, if the air is humid enough, rain or snow forms

8. Types of Fronts Fronts are classified according to the advancing air mass

9. Cold Front (Frontera Fria) – boundary between an advancing cold air mass and the warm air mass it is replacing May produce severe thunderstorms (tormenta) or snow showers

10. Warm Front (Frontera Caliente) – when warm air displaces cold air Can produce rain or snow that will last for a long time

11. Occluded Front (Frontera Oculidida) – when warm air is caught between 2 cold air masses Produces clouds and precipitation

12. Stationary Front (Frontera Estacionario)– a front that is not moving forward Produces precipitation that may last for days (just what we need for a snow day)

13. Low Pressure Systems

14. When forecasters say a low pressure area or storm is moving toward your region, this usually means cloudy weather and precipitation are on the way Low pressure systems have different intensities with some producing a gentle rain while others produce hurricane force winds and heavy rain

15. The centers of all storms are areas of low air pressure.

16. Air rises near low pressure areas. As air rises, it cools and often condenses into clouds and precipitation.

17. Air moves counterclockwise around a low pressure system in the Northern Hemisphere Because of this, cold air is found to the north and west of low pressure areas while warm air is found to the south and east of low pressure areas.