Hurricane Danny continues to strengthen and could become at least a Category 2 on Friday. (NOAA)

This post has been updated.

In a mission to investigate the intensifying storm, Hurricane Hunters flew through the core of Hurricane Danny and found that it has strengthened to a Category 3 with sustained winds of 115 mph — a major hurricane on the Saffir Simpson scale.

Prior to Danny, the most recent major hurricane, Category 3 or stronger, was Hurricane Gonzalo in 2014. However, Danny is very far south in the Atlantic — the last major hurricane that formed this far south was actually Fred in 2009. The median date of the first major hurricane formation is Sept. 4.

Hurricane Danny will likely peak in intensity on Friday and Saturday and is on course to sweep over the Antilles islands in the Caribbean early next week. It will probably start to weaken by Sunday as it tracks west across the tropical Atlantic. The National Hurricane Center is forecasting Danny to reach the northern Lesser Antilles on Monday, probably as a tropical storm.


Track and intensity forecast for Hurricane Danny as of 5 a.m. Friday. Note that the forecast cone is not an impact cone; it only shows where the center of the storm could track. (National Hurricane Center)

Despite being a very strong storm, micro-Hurricane Danny is very small, with tropical-storm-force winds only extending out to a radius of about 60 miles. For comparison, the average radius of tropical storm force winds for an Atlantic hurricane is 150 miles.

A side-by-side comparison of visible satellite images of Hurricane Danny (2015) and Hurricane Bill (2009) is shown below at the same scale — they are shown at about the same location, intensity and date.


Size comparison of hurricanes Danny (left) and Bill (right), at the same scale, and close to the same date, intensity, and location. (images from NRLMRY)

The forecast models have shifted Danny’s possible track slightly northward, and the official forecast from the Hurricane Center falls on the southern end of what the models are suggesting. In terms of intensity, models are in full agreement that Danny will peak today, then weaken in the coming days. In fact, it’s possible that in five days, Danny will have dissipated entirely.

The tiny storm is still surrounded by very dry and dusty air that has wafted out over the tropical Atlantic from the Sahara Desert. However, since Thursday morning, Hurricane Danny has remained isolated from the harsh conditions.

But another huge obstacle lies ahead: wind shear. Put simply, wind shear is how the winds change as you go up in the atmosphere. Even moderate wind shear is destructive to tropical cyclones, and strong wind shear can completely destroy even a strong storm. The subtropical jet stream, where wind shear is very high, is positioned over the Caribbean and up through the Windward Islands. Forecast models suggest that it won’t budge or weaken much in the coming days. This could very easily be what rips Danny apart.


Vertical wind shear forecast from the 06Z GFS run, valid today (top), Sunday morning (center), and Tuesday morning (bottom). (tropicaltidbits.com)

Looking back at storms that have taken a similar track to Hurricane Danny, there are just 21 storms that fit the bill. To be counted, the storm must have occurred during August and passed within 200 miles of Danny’s current location and its forecast positions over the next five days. The list includes some memorable names like Cleo (1964), David (1979), Frederic (1979), Dean (2007) and Isaac (2012).

However, not a single storm on the list occurred during a strong El Niño event, which we are in right now, so Danny is forging a path in history!