[itsinthebag]

TWC says pressure has dropped to 902 mb.

Can you explain to me what this means? What do you mean by pressure dropping to 902 mb?

[Moose4]

That means that the estimated barometric pressure at the center of the hurricane is 902 millibars, or 26.63 inches of mercury. "Standard" atmospheric pressure is 1000 millibars, or 29.92 inches of mercury. The lower the pressure at the center of a hurricane, the stronger the winds are and the stronger the storm generally is, so it's used as an indication of how powerful a hurricane we're dealing with.

902 mb is exceptionally low. I think that makes Katrina the fourth or fifth strongest Atlantic hurricane ever recorded...with twelve more hours of 90-degree water between it and the coast.

Dear God.

}:-)4

[mvpel]

A "bar" is a metric-system measurement of pressure. Think "bar"-ometer. It's 100,000 Newtons per square meter.

A pressure of 1,000 millibars (mb) is the normal sea-level pressure. A pressure of 902 mb means that the pressure is extremely low, around 10% below what it normally is, equivalent to an altitude of about 3,000 to 3,500 feet above sea level in normal weather.

See http://www.usatoday.com/weather/wbarocx.htm for details.

[monday]

"Can you explain to me what this means? What do you mean by pressure dropping to 902 mb?"

Millibars is a measure of atmospheric pressure. The eye of a hurricane creates a low pressure area which acts as a vacuum which sucks surrounding high pressure air into it. The lower the pressure in the eye the faster the winds blow as they wrap counter clockwise around the eye.

A hurricane acts as a giant air pump that sucks warm moist air from the lower atmosphere above the ocean and pumps it up into the upper atmosphere creating rain and vicious winds in the process.