Category Archives: Tropical
Hurricane season in the Atlantic Ocean basin runs from June through November.
The National Oceanic and Atmospheric Administration (NOAA) is predicting 10 to 16 named storms this season. Continue reading
The recent extremely powerful Hurricane Patricia off the west coast of Mexico, the most intense hurricane ever measured in the Western Hemisphere, was noteworthy for a number of reasons.
Perhaps primarily, it was characterized by the incredible fact that its central minimum pressure decreased by 100 millibars in 24 hours from Oct. 22-23. Since the average sea-level pressure is just over 1,000 millibars, that means that 10 percent of the atmospheric column over the center of Patricia was somehow evacuated in only one day. Continue reading
There are two important components of hurricane forecasting: the hurricane track (or where it is going) and hurricane intensity (or how and if its winds are increasing). Track forecasts have improved over the last two decades; intensity forecasts have not improved.
In 1992, when Hurricane Andrew hit Florida, the average three-day forecast error in hurricane track was about 300 miles. Today, a six-day forecast of the typical hurricane track error is now less than 200 miles, more accurate than the three-day forecast was 23 years ago. Continue reading
The 2013 Atlantic hurricane season officially ended on Saturday. It was the least active year in 30 years. There were only 13 tropical storms, two hurricanes and no major hurricanes. The two hurricanes that formed were very weak. In an average year, there are 12 tropical storms; six or seven go on to become hurricanes and two of those reach major hurricane intensity. Continue reading
Forming over tropical oceans ensures that warm sea-surface temperature (SST) provides a mature hurricane with a means to warm and moisten the air that flows toward the important eye-wall convection. Thus, it is not surprising that hurricanes struggle to develop if the SST is not 79.7 degrees F or warmer. Tropical cyclones also require environments in which the wind speed and direction changes very little with increasing height, in other words, where the vertical wind shear is small. Continue reading