Re: Hurricane Joaquin Threatens East Coast, Gains Strength Over Record-Hot Ocean
Sea surface temperatures in the vicinity of Hurricane Joaquin are currently the warmest ever recorded. Hurricanes are fueled by warm water, contributing to an increase in the frequency of the most intense hurricanes, and an exponential increase in damage. Virtually every measure of hurricane activity in the Atlantic has increased substantially since the 1970s, due to the combination of human-caused climate change and natural variation.
Joaquin sustained maximum sustained wind speeds of 125mph as it passed over the Bahamas, and its October appearance is drawing comparisons to Superstorm Sandy. Virginia and New Jersey governors have already declared a State of Emergency.
Simply put, climate change is causing more destructive hurricanes in the Northwest Atlantic. For more detailed information see Climate Nexus’ Hurricane backgrounder, and this note is also available.
The waters that Joaquin is moving into are at record or “much warmer than average” temperatures.
Rising sea levels increase the probability of storm-induced surges and flooding.
As the oceans absorb more heat they expand, elevating sea levels. And as glaciers and ice sheets melt, global sea level is rising, giving hurricane storm surge a higher platform from which to run up onto land.
The New York harbor, for example—one of the areas most damaged during Superstorm Sandy—has experienced nearly a footof sea level rise over the last century, compared to eight inches globally. Due to global warming, the risk of major New York City and New Jersey coastal flooding—like that observed during Superstorm Sandy—has increased from once every 500 years, to once every 25.
Climate change loads hurricanes with additional moisture, intensifying rainfall.
Hurricane Irene (2011) brought greater than five inches in totaland sometimes two to three inches per hour in some locations, leading to extreme flooding like the 500-year Schoharie Creek flood in New York.
Human-caused warming meant Hurricanes Katrina (2005) and Ivan (2004) also carried significantly more rainfall, (6 to 8 percent more, relative to 1970). That increase may have contributed to the breach of the levees in New Orleans.
Joaquin still lacks a crisp, well-defined eye on infrared satellite imagery, but its showers and thunderstorms have continued to intensify and consolidate into a large and increasingly symmetric central core. Hurricane-force winds remain confined to a radius of 35 miles from the center of Joaquin, while gales extend out up to 140 miles. The most recent minimal central pressure was 951 millibars, a hefty drop of 37 millibars in roughly 18 hours. Very warm sea-surface temperatures of around 30°C and relatively deep ocean heat content will support even more strengthening over the next couple of days. Hurricane warnings are in effect for the central and northwestern Bahamas, with a hurricane watch for Bimini and Andros Island and a tropical storm warning for the southeastern Bahamas and Andros Island. My Wednesday afternoon update with Jeff Masters has more detail on potential impacts to the Bahamas from this formidable hurricane.
Moderate northerly shear will relax significantly on Thursday into Friday, and it’s possible that Joaquin will have outflow jets helping to ventilate the storm on both its west and east flanks. Together with record-warm SSTs, these factors could help make Joaquin a dangerous Category 4 storm, in line with the latest NHC outlook, which produces peak sustained winds of 140 mph on Thursday night.
Key takeaway – several models show the storm impacting US East Coast, the very well respected ECMWF says it’s going to veer away. When Sandy hit the US, it was the ECMWF that called Sandy’s hard left hook into New Jersey. Other modelers say they’ve upped their game since then.
Stay tuned.
