why do we use SLP when a hurricane is above our heads?

[the_winds_that_sheared_me]

This may sound like a stupid question but I wonder this. If we use sea level pressure (I guess that is the pressure at the level of the top of the ocean) then what does that have to do with a hurricane that is way up in the sky? Shouldnt we use ceiling level pressure-the pressure at the bottom of the clouds? Or is there something going on at sea level that no one sees but is more important than the clouds?

[x-y-no]

Well, last time I checked ... most of us are still living on the surface, not in the clouds.

[Hybridstorm_November2001]

Exactly, thus we would be effected by the surface layer part of the storm, not the mid or upper level portions.

[the_winds_that_sheared_me]

But we are affected by the wind and rain that comes from the cloud level which is also where all the action of the storm is.

[Hybridstorm_November2001]

True, but not all of that weather (rain and wind) gets down to the surface.

[x-y-no]

But we are affected by the wind and rain that comes from the cloud level which is also where all the action of the storm is.

I'm not sure what you mean by that. The "action" of a storm is in the whole column from the surface to the top of the troposphere.

But when it comes to gauging how a storm will impact humans, obviously it's surface conditions which matter. These aren't independent things, of course, which is why we fly recon missions to measure as much of the environment as we can. But the ultimat concern is to be able to predict the impact on humans - which means predicting the surface conditions.

[Jim Cantore]

True, but not all of that weather (rain and wind) gets down to the surface.

It's too busy flying sideways

[Aslkahuna]

Sea Level pressure is used to have a standard level for the analysis of conditions at the surface. It was decided long ago to use sea level for this purpose since initially weather was mostly the concern of Mariners. Because land surfaces vary in height, some sort of standard level had to be used to properly display surface weather conditions. There are also upper air charts which display the system in other levels of the atmosphere other than the surface. That said, however, it should be noted that being a warm core system, a hurricane is actually strongest in it's low levels specifically about at the top of the boundary layer because
frictional effects become a factor within the boundary layer.

Steve