For folks who live along the east coast of the United States, have heard meteorologists say that a storm system or low pressure area is bombing out or that bombogenisis is about to occur. What do these terms actually mean? When a low pressure system or mid-latitude cyclone moves off of the East Coast of the United States during the colder months of the year, there is a tendency for many of them to intensify rapidly due to the warmer waters of the Gulf Stream and the positioning of the low between two very different air masses.
The air mass to the storm's north and west is usually very cold and dry while the air mass to the storm's south and east is very warm and moist. The storms rapid intensification is known as "bombogenesis" or we meteorologists say the storm is bombing out.
The heat given off by the ocean is like fuel for the storm. Barometric pressure can drop rapidly causing the winds to increase rapidly. To bomb out, the pressure must drop 24 millibars in 24 hours. This is the reason nor'easters grow very strong and wreak havoc on the east coast. The warm moist air is extremely plentiful off the southeast coast.
This energy feeds into the developing storm via the warm sector of the low. The warm air then rises as it encounters cooler air to the north. This rising motion causes condensation (clouds) to occur which then leads to precipitation. The condensation process actually creates heat (latent heat) and this process further adds fuel to the storms energy. Upper level winds and conditions also add to the intensification process. If you look at a surface analysis map with the isobars, which are lines that connect equal barometric pressure, you will see that the lines are packed closely together in a storm that is bombing out.
This indicates that the pressure gradient is steep and that the winds are strong. These storms sometimes produce hurricane force winds and they cover a large piece of real estate, extending farther than even the largest hurricanes. Above is the surface weather map from Wednesday morning of a Low pressure area which bombed out and produced 1-2 feet of snow from NYC to Bostom in less than 24 hours.
Follow me on Twitter: twitter.com/weatherjoshfitz
Post your comments below and keep those great questions coming!