Joaquin likely to impact US East Coast, local impacts uncertain

Hurricane Joaquin strengthened this morning, with maximum sustained winds of 80 miles per hour, in the Caribbean. The hurricane is expected to strengthen further over the next few days as it meanders in the Southwest Atlantic. Warm waters and minimal shear will continue to support storm organization. Thereafter, Joaquin is expected to make a turn northward, moving into the Southwest Atlantic Ocean. As it does so, an energetic disturbance over the Southeast States will race toward the storm. As the two phase, Joaquin is expected to accelerate and make a rapid turn west toward the Mid-Atlantic coast.

Exactly where the storm tracks, and how strong it is, remains highly uncertain at the present time. Forecast models are struggling with intricate details of the atmospheric setup. Unsurprisingly, small changes in the atmospheric interactions will have big changes on the eventual outcome and effects along the East Coast. The potential envelope of solutions remains extremely large — and so this post will attempt to explain the atmospheric setup, potential scenarios, and possible hazards in our area

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What is causing the potential for Joaquin to swing back toward the coast?

Blocking, blocking, blocking. We wrote yesterday about how high latitude blocking will be establishing itself over Canada and the Northwest Atlantic as Joaquin moves northward. This is incredibly important and, quite frankly, driving the potential for the storm to impact the US East Coast at all.

A mid level atmospheric ridge is building over the Central and Western Atlantic, while a mid level ridge and surface high pressure is strengthening over Southeast Canada and the Northwestern Atlantic. As Joaquin attempts to move northward and eventually seaward, the storm is “blocked” by these high pressures.

Atmospheric setup for Hurricane Joaquin. Note the blocking ridge (red) that inhibits the storm from moving out to sea.

This means that any disturbance driving southeastward over the Mississippi Valley or Southeast States has the potential to interact, or phase, with Joaquin, and quickly swing the storm back toward the East Coast as it does so. This is precisely what is being modeled now.

As this mid level energy drives through the Southeast states, it “captures” Joaquin, and swings it back toward the coast. The storm can only move so far north, due to the blocking ridges, and then accelerates and swings westward.

What are the current uncertainties and issues with the forecast?

Forecast models are currently struggling with small details in the life cycle of Joaquin. Exactly how the storm behaves over the next 24-48 hours will be critical to the forecast. Just today, the GFS model struggled and initialized Joaquin 10 millibars too weak. Each forecast model has a slightly different idea as to how the storm will behave, and these small differences have huge impacts on the forecast.

Making matters worse, models are struggling with the location and intensity of blocking, as well as the exact timing and strength of the mid level trough which will “capture” Joaquin. Some models are farther south and more aggressive with this feature, while others are slower and weaker. Some even let Joaquin meander in the Carribean so long that it escapes eastward out to sea.

The latest modeled tracks for Joaquin, showing a developing consensus on a Mid Atlantic landfall.

The obvious issue here is that forecast models don’t offer much confidence on any one specific or particular outcome at this time. They each show a unique situation, with landfalls ranging from the Carolinas to New Jersey. The models will continue to change, and begin to hone in on a consensus, over the next 2 to 3 days.

Most recently, two more distinct camps of potential scenarios developed. The first group of models takes Joaquin northward, before interacting with the mid level trough over the Central US and moving quickly westward into the Mid Atlantic States. The second allows Joaquin to meander enough so that it stays farther east. The former scenario would obviously have much greater impacts for the Eastern Seaboard.

What potential hazards would affect our area? 

Obviously, rain and wind would both be potential hazards should Hurricane Joaquin make a move toward the United States East Coast. Even if the storm makes landfall well south of our area, the wind field of the storm would expand enough to impact at least parts of the forecast area.

Additionally, rainfall could be expansive even if the system is hundreds of miles away. A frontal boundary near the area, interacting with tropical moisture, could provide several inches of additional rainfall.

WPC (NOAA) predicting over 8 inches of rain in a large majority of the Northeast US over the next several days.

Near the area coasts, onshore winds and local flooding would be possible as the storm moves inland over the Mid Atlantic.

Again, the exact track of the storm will have major implications on the exact local impacts. At the present time we are not anticipating Joaquin to make landfall in New Jersey or New York. 

What can I do to prepare? 

While panic is obviously not necessary, preparation is always encouraged. While the eventual outcome of Joaquin is still uncertain, all residences should make sure that a plan is in place should the storm make an approach toward the area. This is especially true for residences near the coast.

Be sure to have an evacuation plan in place, should evacuations become necessary. Make sure to have a stock of necessary supplies — including food, water, batteries, and flash lights. In addition, be sure to have a plan and place for any loose objects outside that you may need to tie down.

Again — and we wish to stress this — we are not expecting Joaquin to make direct landfall in New Jersey or New York. But the effects of the storm are likely to still be felt. The degree to which we feel the effects is yet to be determined.

Being prepared is always smart — and we encourage you to do so.

Stay tuned over the next few days for a continuous stream of updates and information as the eventual outcome of Joaquin becomes more clear.