The future track of Hurricane Joaquin is uncertain and anxiously anticipated by coastal residents from North Carolina to New England. Steering winds high in the atmosphere will ultimately determine where Joaquin will track, and these winds are looking very similar to past cases of hurricane landfalls in the Mid-Atlantic.
Recent forecast models are mostly calling for a landfall along the Mid-Atlantic coast this weekend, with the notable exception of the European model. While it is tempting to dismiss the European as an outlier, it has historically been one of the most reliable models for hurricane tracks. In 2012, it nailed Hurricane Sandy’s northwest turn several days before other models predicted a similar track.
The question at this point is whether or not these models are correctly identifying and predicting the steering winds that Hurricane Joaquin will ride over the next few days. The ramifications of a track toward the East Coast — or away from it all-together — are critical for millions of Americans.
So what have past hurricanes done in similar situations?
Historically, landfalls along the mid-Atlantic coast from North Carolina to Delaware are rare in October. Only two hurricanes have impacted North Carolina after Sept. 30 — Hurricane Hazel in 1954, and Hurricane Irene in 1999.
Hurricane Hazel devastated the Carolinas as it barreled inland on Oct. 14, 1954, and then went on as a non-tropical storm to deliver hurricane-force winds to Toronto. Hurricane Irene brushed by the Outer Banks on Oct. 18, 1999, bringing hurricane-force winds to the coast while the center of the system remained offshore.
Clockwise circulation around a high pressure ridge to the north and northeast of the hurricane will often mean a hurricane cannot curve eastward into the open Atlantic, since it would be going against the steering winds. Instead, this clockwise wind flow around the southern edge of high pressure grabs the hurricane and pushes it west.
Eric Webb, a student at North Carolina State University, created a graphic to illustrate the mid-level steering flow for 13 tropical storms that impacted the Mid-Atlantic since 1900. Strong high pressure over the Northeast — which is needed for such a track — is clearly evident.
There’s a very similar setup in the forecast later this week, when Hurricane Joaquin is expected to be approaching the East coast. This is almost a carbon copy of what has been historically observed during Mid-Atlantic hurricane landfalls. This strong high pressure area blocks the tropical cyclone from recurving out to sea and avoiding the Eastern Seaboard.
The final track of Joaquin is dependent on a variety of complicated factors. The system is currently drifting southwest without much steering flow under a mid-level ridge of high pressure. A strong area of low pressure is forecast to dive down into the Southeast over the next couple of days. How that low pressure area and ridge play out will likely determine the final track of Joaquin.
Additional weather balloon launches in the Eastern U.S., are currently being conducted, along with a synoptic aircraft reconnaissance mission from NOAA. These efforts will provide valuable information on the mid-level steering flow, and will be ingested into the forecast models which will hopefully add clarity to Joaquin’s future track.