from The American Heritage® Dictionary of the English Language, 5th Edition.
- noun The transfer of a property of the atmosphere, such as heat, cold, or humidity, by the horizontal movement of an air mass.
- noun The rate of change of an atmospheric property caused by the horizontal movement of air.
- noun The horizontal movement of water, as in an ocean current.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun earth science, chemistry The
horizontal movementof a body of atmosphere(or other fluid) along with a concomitant transportof its temperature, humidityetc.
- noun The
transportof a scalarby bulk fluid motion.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- noun (meteorology) the horizontal transfer of heat or other atmospheric properties
from The American Heritage® Dictionary of the English Language, 4th Edition
from Wiktionary, Creative Commons Attribution/Share-Alike License
The GFS, NAM and the latest European model all predict a period of light precipitation in association with warm air advection well out ahead of the main storm late Monday into Tuesday.
The low center at around 5000 feet passes to our north with little or no warm air advection to transport much moisture into the region.
Also, instead of having the 850 mb (5000 ft) cyclonic (low pressure) circulation pass just to our south, the strong northern stream initially keeps any circulation at 850 mb well to our northwest so the region ends up in a broad region of warm air advection (winds from the south) which leads to warming.
Where the winds (flag shaped symbols) are blowing across the temperature lines is where warm advection and lifting is taking place (right hand side of the figure below).
Satellite imagery of the President's Day storm indicated all the bright clouds and precipitation associated with the warm advection were shifting out to sea mostly south of DC and that the city might only add another inch of snow to the four that had fallen earlier in the evening.
The system has very little upper level energy with most of its lift being supplied by warm advection winds from the south.
Low level cold advection (a precipitation inhibitor) will be battling the dynamics associated with the upper trough (a precipitation producer).
Nonetheless, both models now are showing a period of moderate to strong warm air advection winds coming in from the south increasing moisture.
The low level flow ahead of the Great Lakes low is fairly weak at that time which will keep the low level warm advection and mixing to a minimum which could allow surface temperatures in the colder suburbs to remain near or below freezing at the precipitation's onset.
However, all the models show any precipitation associated with this feature drying out as it crosses the mountains and there's no moist flow from the south warm air advection to generate the lift necessary for much snow to develop.