Warming Atmosphere and the Impact on Current and Future Hurricanes

Hurricane Irma broke many records as it moved through the Atlantic and into the southeast United States.  If we look at the climatology of hurricanes that typically form that far east in the Atlantic, most of them curve back out to sea and do not have much of an impact on the United States.  This is most likely due to them getting caught up within the jet stream and pushed back east.  Hurricane Irma, however, did not do that.  It continued on its westward track quickly becoming a Category 5 hurricane before reaching South Florida.  To understand why this happened, we have to look at what's going on in the atmosphere.

When we think about the atmosphere, we have to think of it three dimensionally.  As the air warms, it expands and when it cools, it contracts.  The atmosphere has different height levels, like floors in a tall building, from the surface to the top.  As the atmosphere warms it causes the height levels throughout the atmosphere to rise - allowing high pressure to develop.  Examining the height levels at roughly 18,000ft over the Atlantic, meteorologists noticed they've been higher/warmer than normal.  The result of this caused a blocking ridge of high pressure to develop which helped steer Hurricane Irma more west, rather than north.

Sea Surface Temperature
Anomaly over the Past Month

Another likely factor for the rapid development of Hurricane Irma are the warm sea surface temperatures over much of the Atlantic.  If we look back to sea surface temperatures over the past month, and compare it to what is typically normal for this time of year, we can definitely see a warming trend over the Atlantic and into the Gulf of Mexico.  Warm ocean waters are fuel for tropical cyclones, allowing them to continue their development into tropical storms and potentially hurricanes.

So what can this tell us about hurricanes that form in that area and their potential impacts on the United States in the future?  It could actually tell us a lot.  There will likely be many studies done to try and understand just how those factors, along with many other, impact the future development of hurricanes.  As the climate continues to change and ocean waters continue to warm, we need to understand just what impacts that will have on our weather patterns.  While climate change didn't cause Hurricane Harvey and Hurricane Irma, it more than likely had a role in both the strength and overall track of those storms.