STORM2K

Probably a fairly simple question. Is a Upper level high pressure a good, bad or indifferent condition for the development of a tropical disturbance, assuming it is directly over the disturbance. I know it is conducive for a system that is developed already acting as an exhaust for the heat engine. It seems to me as an Upper High would suppress a disturbance in infant-ency as much as any exhausting it might do. Is this all relative or do I have a Clue?

Yes, an upper level high, or anticyclone is very beneficial for tropical cyclogenesis. Why? Well, what an anticyclone does is create a favorable upper level environment as well as help the outflow channels of a cyclone. If you have any more questions feel free to message me.

If the pressure is high in the Mid to upperlevels, T-storms would have a harder time developing because of the waemer temps aloft(capping) so in effect surpressing development. I know after a storm has reached 40,000 ft or so it will provide venting.

tailgater wrote:If the pressure is high in the Mid to upperlevels, T-storms would have a harder time developing because of the waemer temps aloft(capping) so in effect surpressing development. I know after a storm has reached 40,000 ft or so it will provide venting.

Remember, "upper level" is a description of the pressure, not the height. Weather charts are plotted at pressure levels, and the numbers on the chart (with the exeption of the SFC plot) are the heights of the pressure, so when someone refers to the "upper levels" they are talking about the 400mb to 200mb range. Pressure doesn't change at a set level (the pressure at the 300mb level is always 300mb). When someone refers to an upper level "high" they are referring to higher isobaric heights. Picture the 300mb height as a surface, and higher heights would be a hill on that surface. Since air is not a solid, it will "flow" out of that higher surface into the lower heights surrounding it.

This flow from the higher heights to the lower heights is the outflow that fuels the tropical storm, because the replacment air for the outflow comes from below. As the air rises from below it releases latent heat, becomes more buoyant, and fuels the storm. Since it isn't "pushing down" on the surface, its not really suppressing anything (if it was pushing down, then you would not have a low pressure on the surface).

theavocado wrote:

tailgater wrote:If the pressure is high in the Mid to upperlevels, T-storms would have a harder time developing because of the waemer temps aloft(capping) so in effect surpressing development. I know after a storm has reached 40,000 ft or so it will provide venting.

Remember, "upper level" is a description of the pressure, not the height. Weather charts are plotted at pressure levels, and the numbers on the chart (with the exeption of the SFC plot) are the heights of the pressure, so when someone refers to the "upper levels" they are talking about the 400mb to 200mb range. Pressure doesn't change at a set level (the pressure at the 300mb level is always 300mb). When someone refers to an upper level "high" they are referring to higher isobaric heights. Picture the 300mb height as a surface, and higher heights would be a hill on that surface. Since air is not a solid, it will "flow" out of that higher surface into the lower heights surrounding it.

This flow from the higher heights to the lower heights is the outflow that fuels the tropical storm, because the replacment air for the outflow comes from below. As the air rises from below it releases latent heat, becomes more buoyant, and fuels the storm. Since it isn't "pushing down" on the surface, its not really suppressing anything (if it was pushing down, then you would not have a low pressure on the surface).

Thanks very much Avocado. very nice explanation.
I have done a little reading, since asking this question and now think I was confusing Upper highs with temperature inversions(capping). Just goes to show how much information goes into a forecast.