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A depressed storm? When does a depression become a tropical storm or a hurricane?
Anatomy Of A Tropical Depression
How does a tropical depression form?
Thunderstorms occur in the summer over the ocean with great frequency. But when these storms begin to cluster and maintain their strength, they can become what’s known as a tropical disturbance.
As circulation organizes and the storms continue to strengthen, what can form is a tropical depression. The term depression has to do with the storm system being an area of low (depressed) air pressure.
While tropical depressions do not have eyes like hurricanes and typhoons, a tropical depression nevertheless is a centralized area of storms. A tropical depression doesn’t have average wind speeds of greater than 38 miles-per-hour (MPH).
However, a tropical depression can pack:
- A lot of rain
- Gusty winds
Unlike hurricanes, typhoons, and tropical storms, tropical depressions aren’t named (like Hurricane Elena or Tropical Storm Marco) — they’re numbered. They’re often abbreviated TD for short and referred to as TD 1, TD 2, and so on.
Benefits Of A Tropical Depression
Usually, we don’t usually want to hear about any tropical weather heading our way.
But tropical depressions can be seen as a gift for areas hard hit by drought conditions.
While injuries and deaths can be caused by floods, tropical depressions don’t typically pack the violent punch hurricanes, typhoons, and even some strong tropical storms have to offer. Tropical depressions can dump enough good, soaking rain to release an area from a heavy drought, and the cloud cover and breezes can also help to relieve heat-stricken areas of the country.
Tropical depressions can and do overpass land areas.
While passage over land normally causes a storm to lose strength, there are occasions when passage over land does not obliterate a tropical system. Such is a common occurrence when a tropical depression crosses over small islands.
Storms That Make Landfall Twice Or More
There have been many instances when a tropical depression has gone over a land mass like the peninsula of Florida only to gain more strength after again reaching water. Once these tropical depressions reach water and strengthen into a tropical storm or hurricane, they typically keep marching forward… and will strike whatever may still be in front of them, including other areas of land.
Many tropical depressions will hit Florida from the east, cut across the state’s peninsula (the long part of the state that hangs south into the water), and either head west for places like Texas or Mexico, or curve north and target Louisiana, Mississippi, or Alabama.
And if one hit by a tropical depression isn’t enough, how about this: many tropical depressions, tropical storms, and hurricanes will strike the lower tip of Florida’s peninsula and then turn dew north and strike Florida’s panhandle — the part that attaches to the rest of the United States! So, as you see, its possible for 1 storm to hit 1 state twice.
How Does A Tropical Depression Become Stronger?
As tropical depressions become stronger, they can grow into larger storms. Once average wind speeds reach 39 MPH or greater, a tropical depression becomes a tropical storm.
The biggest threat of a tropical storm, like a tropical depression, is typically rain — not wind. However, a tropical storm is nothing to sneeze at.
- Rains can become torrential with a tropical storm.
- Winds can be as high as 73 MPH.
- Even a typical tropical storm with winds in the 40 to 60 MPH range can cause light-to-moderate wind damage, especially to trees, outdoor furniture, RVs, mobile homes, and manufactured homes.
As any tropical system becomes stronger, the barometric pressure usually drops, too. When a tropical storm becomes better developed, winds become stronger, and the storms become more intense, a tropical storm is likely to turn into a hurricane.
Hurricanes have winds of at least 74 MPH and can cause moderate to severe wind damage and torrential rains.
- Hurricane Andrew, which hit Florida in 1992, literally wiped out the town of Homestead (just outside of Miami) with catastrophic winds.
- Hurricane Katrina in 2005 flooded out New Orleans and surrounding areas of the Gulf Coast; hundreds of thousands of people were forced to move from their homes and many have not since returned.
I'm a weather geek from Florida who's been studying meteorology and watching weather patterns for years! I enjoy sharing little-known facts and fun stuff about the weather. I especially like sharing interesting details about weather events and conditions that can affect you… and how to prepare for Mother Nature's ever-changing weather patterns.