Tuesday, August 27, 2019

A Normal Start to the 2019 Tropical Storm Season

Two years ago this week Texas and the Gulf Coast were dealing with Harvey, which waddled over the southeast Texas and Louisiana coasts for three days after making landfall, dumping record amounts of rain. Harvey was the eighth named tropical cyclone of the 2017 season. Here in 2019 Tropical Storm Dorian is the fourth named storm of the season, and the former Tropical Depression #6, located midway between the U.S coast and Bermuda, became Tropical Storm Erin Tuesday evening. Right now 2019 is mirroring last year with one named storm in June (Andrea), two in July (Barry, Chantal), and two in August.
Atlantic tropical cyclones as of 10:50 p.m. EDT August 27, 2019. Source: National Hurricane Center

The 2018 hurricane season finished strong, with a total of 16 named storms ending with Hurricane Oscar at the end of October. Four of those storms made landfall in the U.S. Hurricane Michael was a Category 5 hurricane when it made landfall on the Florida Panhandle on October 10.

Track map of all 2018 tropical cylones.

A "normal" tropical storm season (June 1 - November 30), based on data from 1966-2009, is 11 named storms, six of which are hurricanes, with two of those hurricanes Category 3 or greater.

The season tends to ramp up quickly during August and early September, with the peak about September 10.

NOAA's prediction for the tropical storm season (updated 8/8/2019), calls for a likely (70 percent confidence) range of 10 to 17 named storms (winds of 39 mph or higher), of which 5 to 9 could become hurricanes (winds of 74 mph or higher), including 2 to 4 major hurricanes (category 3, 4 or 5) (winds of 111 mph or higher).

All eyes are now on Tropical Storm Dorian, located tonight just east of the Leeward Island and headed toward Puerto Rico. Dorian has not changed much in intensity as of this writing, but is expected to strengthen some before moving across Puerto Rico. The higher terrain of Puerto Rico will cause it to lose some intensity tomorrow before it again emerges over open water and strengthen again late this week. Based in current forecasts Dorian could be approaching Florida by late this weekend. There is a higher than normal uncertainty of the intensity forecast of Dorian due to a large spread in storm model guidance.

"Strengthening" and "weakening" can be somewhat misleading descriptions with tropical systems like this. While winds are what most people tend to think about and focus on, the storm surge, heavy rain, and resultant flooding are what often cause the greatest threats to life and property. You don't need a particularly intense system to produce a lot of rain.

Dorian bears watching. Erin, on the other hand is expected to turn northeast into the Atlantic and weaken to a tropical depression in the next three days. You can find the latest information on Dorian and other tropical systems on the NOAA/NWS National Hurricane Center web site.

1 comment:

  1. This will be interesting 4 days for Dorian.
    Catastrophic flooding will occur if it stalls any turns to go north on FL.
    I should be up high on the ridge to not flood. Went through Charley 21 days with no electricity, cell and learned a lot.
    Hope everyone will be safe.