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Severe Weather and Flooding Expected Across the Southern Plains, Mid South, & Ohio Valley

Strong to severe thunderstorms, including tornadoes, are expected late today and tonight and continuing through Friday from the southern Plains to the Mid South and Ohio Valley, where heavy rainfall and flooding are also likely. Elsewhere, chilly temperatures and heavy mountain snowfall will persist for parts of the West while very mild air prevails along the East Coast. Read More >


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Density Altitude

diagram Density Altitude Concept

On a hot, muggy day, the air becomes “thinner” or less dense, and its density at a pilot’s location is equivalent to a higher altitude in the standard atmosphere.  It is hazardous to aircraft during takeoff and climb because:

- Aircraft power is reduced. The engine will ingest less air to support combustion.

- Aircraft thrust is reduced.  A propeller will have less "grip" on the air, while a jet engine will will exhaust less mass.

- Lift is reduced.  The thinner air will exert less upward force on the airfoils.

As a result, a longer takeoff and landing roll is required, especially for a fully-loaded aircraft.  After takeoff, the aircraft will have a smaller rate of climb and will have a lower service ceiling.

Density altitude is usually reported at each AWOS/ASOS station in the Remarks section of the METAR, if the value is greater than 1000ft higher than the elevation of the airfield.  Here's an example:

METAR KMSY 291400Z AUTO 18006KT 10SM CLR 28/13 A3001 RMK SLP161 DENSITY ALT 1000FT






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Density Altitude