Credit: Flickr/Nurpu. Continental polar (cP) is not as cold as the Arctic air mass but is also very dry. *Air masses are 3-D. Polar and Arctic air masses become shallower moving away from the source region. US Dept of Commerce Extensive floodwater surrounds homes in Colorado. DENVER (CBS4) – Colorado is split down the middle today with two different air masses in place. Polar air masses, designated by the letter 'P', are not as cold as Arctic air masses as they originate over the higher latitudes of both land and sea. It rained as much as 2 inches per hour during this time. As these air masses move around the earth they can begin to acquire additional attributes. Because the rain had to escape through the canyons in this mountainous area, every river in the northern foothills became a raging, destructive river. The rain continued from the evening of the 11th to the morning of the 12th. Tropical air masses, designated by the letter 'T', are warm/hot as they originate over the lower latitudes of both land and sea. As the jet stream changes intensity and position, it affects the motion and strength of air masses. Putting both designations together, we have, for example, a "continental arctic" air mass designated by 'cA', which source is over the poles and therefore very cold and dry. If that same polar air mass moves south from Canada into the southern U.S. it will pick up some of the warmth of the ground, but due to lack of moisture it remains very dry. • The properties of air masses are determined by the underlying surface properties where they originate. This can lead to a fairly narrow band of showers and thunderstorms along or just ahead of the front. DENVER (CBS4) – Colorado is split down the middle today with two different air masses in place. So, fronts just don't appear at the surface of the earth, they have a vertical structure or slope to them as well. The motion of air masses also affects where a good portion of precipitation occurs. Please Contact Us. Maritime polar (mP) is also cold but moist due to its origination over the oceans. Fronts are identified by change of temperature based upon their motion. Accumulating Snowfall Mostly Done On Colorado's Front Range, See Monday a.m. It rained as much as 2 inches per hour during this time. This is especially true north of warm fronts *Low pressure forces air mass movement. The desert region air masses (hot and dry) are designated by 'cT' for 'continental tropical'. Jonathan C. Thibault. National Weather Service The flow around this system sucked the extremely moist air from the south into the northern Colorado foothills. This road and home were destroyed by raging floodwater. A warm front is the opposite affect in that warm air replaces cold air. Equatorial low-pressure trough: This area is in the Earth's equatorial region (0 to 10 degrees north and south) and is composed of warm, light, ascending, and converging air. A road destroyed by floodwater. Credit: Steve Zumwalt/FEMA. That means some help for those fighting the Cameron Peak Fire and CalWood Fire with cooler temps, higher relative humidity and areas of drizzle, fog and low clouds. There is another boundary that exists except this boundary divides moist air from dry air. Fronts & Air Masses Chapter overview: • Anticyclones or highs • Air Masses o Classification o Source regions o Air masses of North America • Fronts o Stationary fronts o Cold fronts o Warm fronts o Fronts and the jet stream o Frontogenesis o Drylines o Occluded fronts o Upper-tropospheric fronts . Credit: Flickr/Nurpu. The low-pressure system caused the moist air to rise, cool and rain. Here’s what that front looked like at 8 am Sunday. Unfortunately by tonight strong westerly winds are forecast to kick in once again and that will push the cooler, more humid air mass off to the east. Warm, moist air from the south moves into Colorado infrequently, but most often in the spring, summer and early autumn. When warm air gets forced by the terrain into higher, colder altitudes, it has to remove some of its moisture by raining. Air masses form over large surfaces with uniform temperatures and humidity, called source regions. With a cold front, a colder air mass is replacing a warmer air mass. These raging, high rivers forced many people to be evacuated from their homes and their towns. Snow Totals, Colorado Weather: Potent Storm Prompts Winter Weather Alerts For Entire State, Snow Helps Slow Spread Of East Troublesome Fire, Snowstorm Brings Critically Needed Moisture To Colorado, Draft Horse, Donkey Released During Wildfire Found 'Singed And Hungry, But Healthy', Snowy Roads And Highways Plagued With Crashes Sunday; CDOT Urges Drivers To Stay Home Monday, Seven First Responders In Grand Lake Lose Homes To East Troublesome Fire, Denver Weather: Arctic Blast With Snow And Record Cold On Sunday, East Troublesome Fire Activity Slowed By Snow, Firefighting Crews Presented With New Challenges. Joseph K. VonNida. To put it in perspective, this part of Colorado usually gets only 20 inches of rain in an entire year. National Oceanic and Atmospheric Administration. National Guardsmen surrounded by floodwater.