Meteorology (Weather)/warm fronts

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QUESTION: Hello Sir,
I would like to ask the following:I read in a meteorology text that a jetstream ridge situated above an area can cause an anticyclone since air below the ridge descends toward the ground.The descending air heats up and a subsidence inversion comes about.Therefore,can an approaching cold front,which lifts up warm air,be prevented from causing condensation cloud formation)due to the subsidence inversion and the stable air aloft?
Thank you

ANSWER: Hi Chris

The short answer is no.

A cold front would not be passing through the center of a high pressure, it would be on the southeast side moving south or southeastward.

A cold front forces pre-frontal warm air upward by displacement thus causing cloud formation and any associated precipitation.

http://www.theweatherprediction.com/habyhints/96/

http://www.theweatherprediction.com/habyhints/253/








---------- FOLLOW-UP ----------

QUESTION: Dear Donald,
I've got a question regarding warm fronts.If the front's warm air rides over the colder air ahead of it and considering the front's slope (which,as I read,has a typical value of 1:150 or 1:200),it seems to me that areas closer to the boundary of the front(i.e.,areas closer to the point where warm air meets up with colder air) have greater chances of getting higher temperatures compared to areas further away to the north(if we consider that warm fronts usually move from south to north).
 So, if we take an area,say, 200 km north of the front,the warm air is in this case 1km above the surface.It appears to me that this warm air doesn't have many chances of warming the surface.So,I guess this area gets warmed up not because the front's warm air really comes in contact with the surface but because it slowly pushes away the colder air ahead of it.Another factor could be the southeasterly or easterly winds that the front brings to this area before it reaches it.
 What do you think of the above? Finally,is it because of the advancing warm air's lower pressure(compared to the colder air that it displaces) that the approach of a warm front lowers barometric pressure?
  Thank you

Answer
Hi Chris

The further away from the surface warm front, the less impact of warmness penetrating the cold airmass to the north. The dramatic warmer air would only reach the northern area to the north of the progressing warm front/mass and be the significant factor to change the surface temperature by advection of warm air at the surface. The barometric pressure change is related to the approaching low pressure area that the warm front is attached to:

http://www.erh.noaa.gov/rnk/Newsletter/Fall_2010/images/heavy_rain_pattern/cool_

https://courseware.e-education.psu.edu/public/meteo/meteo101demo/Examples/Section9p06.html

http://www.theweatherprediction.com/habyhints/254/  

Meteorology (Weather)

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Donald Rosenfeld

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Any questions (except private) answered from the 1st grade level on up pertaining to any aspect of Weather. I am a 20 year member of the American Meteorological society and a long time forecaster of eastern United States snow storms and Hurricanes.

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