Fronts Any boundary between 2 different air masses Generally means a change in weather Four Types (cold, warm, stationary, and occluded)

Cold Front

Warm Front

Stationary Front

Occluded Front

cA cP mT

cA cP mT

cA cP mT mT

cA mT cP mT mT

Where Are The Air Masses And Fronts?

Cold Front cA mT

Severe Weather Risk Box cP mT Severe Weather Risk

Where are the Fronts? L

Where are the Fronts? H L L

L cP mT

Where Are The Fronts? 07-04-07

Thursday June 18, 2009 mT

Warm to cold; humid to dry. Windy, showers, thunderstorms. Cold Front Warm to cold; humid to dry. Windy, showers, thunderstorms.

Cold Front When a cold air mass replaces a warm air mass. They generally move from NW to SE. Before Passing While Passing After Passing Winds Temp Clouds Precipitation

Cold Front When a cold air mass replaces a warm air mass. They generally move from NW to SE. Before Passing While Passing After Passing Winds S – SW Gusting N - NW Temp Clouds Precipitation

Cold Front When a cold air mass replaces a warm air mass. They generally move from NW to SE. Before Passing While Passing After Passing Winds S – SW Gusting N - NW Temp Warm Sudden drop Steadily dropping Clouds Precipitation

Cold Front When a cold air mass replaces a warm air mass. They generally move from NW to SE. Before Passing While Passing After Passing Winds S – SW Gusting N - NW Temp Warm Sudden drop Steadily dropping Clouds Cirrus, cirrostratus cumulonimbus cumulus Precipitation

Cold Front When a cold air mass replaces a warm air mass. They generally move from NW to SE. Before Passing While Passing After Passing Winds S – SW Gusting N - NW Temp Warm Sudden drop Steadily dropping Clouds Cirrus, cirrostratus cumulonimbus cumulus Precipitation Showers Heavy rain, storms clearing

Warm Front Clouds/fog. Light to moderate rain or snow or sleet/freezing rain for many hours or days.

Warm Front When a warm air mass replaces a cooler air mass. They generally move from SW to NE. Before Passing While Passing After Passing Winds Temp Clouds Precipitation

Warm Front When a warm air mass replaces a cooler air mass. They generally move from SW to NE. Before Passing While Passing After Passing Winds S – SE Light, variable S - SW Temp Clouds Precipitation

Warm Front When a warm air mass replaces a cooler air mass. They generally move from SW to NE. Before Passing While Passing After Passing Winds S – SE Light, variable S - SW Temp Cold, slowly warming Steady rise Warmer, then steady Clouds Precipitation

Cirrus, cirrostratus, nimbostratus Warm Front When a warm air mass replaces a cooler air mass. They generally move from SW to NE. Before Passing While Passing After Passing Winds S – SE Light, variable S - SW Temp Cold, slowly warming Steady rise Warmer, then steady Clouds Cirrus, cirrostratus, nimbostratus Stratus type stratocumulus Precipitation

Cirrus, cirrostratus, nimbostratus Warm Front When a warm air mass replaces a cooler air mass. They generally move from SW to NE. Before Passing While Passing After Passing Winds S – SE Light, variable S - SW Temp Cold, slowly warming Steady rise Warmer, then steady Clouds Cirrus, cirrostratus, nimbostratus Stratus type stratocumulus Precipitation Light to moderate Drizzle Usually none

Cold and Warm air masses meet, but neither can move the other. Stationary Front Cold and Warm air masses meet, but neither can move the other. Light to moderate rain, ice, or snow. Followed by milder weather or cooler weather

A warm air mass is caught between two cooler air masses. Occluded Front A warm air mass is caught between two cooler air masses. Wide variety of precipitation. Can be very windy with heavy rain or snow.

Cold Front Warm Front

Visualizing Fronts

Anticyclones High Pressure centers of dry air. Usually called “Highs” Represented on a weather map with a “H” Winds spin clockwise in the Northern Hemisphere. Causes dry and clear weather/skies.

Cyclones Located on a weather map with a “L” The “L” stands for “low” Indicates an area of low air pressure. Cyclones and decreasing air pressure are associated with clouds, wind, and precipitation. Winds spin counterclockwise in the Northern Hemisphere. As air rises in a cyclone, the air cools and forms clouds and precipitation. They play a large part in the weather of the United States.

Where Did the Fronts Set Up For the First Half of the Month?