Hello Dolly

Dolly.gif

NHC official track forecast for Dolly Tuesday morning

It may not be a major hurricane, but Dolly will pack a punch for south Texas this week.

Dolly is expected to become a hurricane today, and make landfall as a category one hurricane near the Texas-Mexico border late Wednesday.

Like many elements of weather forecasting, hurricane forecasting is part science, part art. Forecasting hurricane tracks and intensity is one of the most difficult forecasts a meteorologist has to make. Hurricanes are spawned in the tropical easterlies. These steering winds are often weak and erratic. Once the storms reach certain latitude they well get caught up in the westerlies, change course and re-curve dramatically to the right.

Still forecasters have shown a great deal of skill with hurricane tracks. The average error for hurricane tracks from 2003 through 2007 was 106 miles in the Atlantic at 48 hours. This is a pretty useful forecast, to have the skill to tell people that a hurricane will come within 100 miles of you location in 48 hours. It’s also a big improvement from 20 years ago when the average hurricane track error was over 200 miles at 48 hours.

Forecasting hurricane intensities is another matter. Hurricanes are notorious for rapid intensity fluctuations as they move over warmer water. Hurricanes approaching the U.S. east coast have been observed to explode with intensity bursts as they pass over the Gulf Stream, a warm ribbon of water that hugs the east coast. Eyewall replacement cycles can change hurricane intensity in just a matter of hours.

It will be interesting to see what happens to the intensity with Dolly over the next 24 hours before landfall. Hopefully it will be as advertised, but you can bet the hurricane forecasters at NHC are pouring over every bit of data to make an accurate landfall forecast.

National Hurricane Center

PH

  • Chris B. Critter

    One needs to keep in mind that many of the worst rainfall events coastal areas have experienced have been from tropical storms or weak hurricanes. Many buildings can stand up to category 1 winds; many can’t stand the 5 to 10 (or 20 or 30…) inches of rainfall and the resulting flooding which can occur far inland.

    What will be interesting to watch is how Dolly progresses across northern Mexico. If it stalls out, someone’s going to get a lot of rainfall. I hope at least some of the water makes it into the Amistad and Falcon reservoirs on the Rio Grande (but it doesn’t look like it).