As it moved through the very warm ocean waters near the Bahamas on Thursday, Hurricane Joaquin strengthened further, reaching Category 4 status on Thursday afternoon. Maximum sustained winds reached 130 miles per hour. The National Hurricane Center suggests additional strengthening is possible, with maximum sustained winds approaching 140 miles per hour.
Computer models have continued their immense struggles with the track and intensity of Joaquin. A storm which was modeled by only a select few to become a major hurricane just days ago, has strengthened far beyond additional expectations. One of the major reasons for this is a farther south track — into warmer waters — which also was not anticipated by modeling until 36-48 hours ago when the ECMWF was the first to suggest a southward jog.
What is causing these changes in forecast modeling?
Less than 24 hours ago, most computer models were all showing Hurricane Joaquin making a hard left turn into the United States. Whether it was solutions in the Carolinas, the Mid Atlantic, or even New Jersey, these modeled solutions were bringing widespread flooding, beach erosion, storm surge, and winds well over hurricane force to much of the East Coast. These solutions also seemed to make sense, too, given how strong the storm was becoming and the blocking pattern in the Atlantic. Our previous post detailed several meteorological reasons why those ideas were supported.
Today, however, forecast models have continued a trend which changes the general forecast synoptics. A southward drift of Joaquin, with increasing influence from an upper level low in the Central Atlantic Ocean, would generally halt its westward and northward movement. Joaquin would instead, meander in the Bahamas before begin a slight turn north and northeast. The increasingly present influence from the upper level low in the Central Atlantic would help steer it slightly northeast, and eventually it would escape the grip of blocking and the incoming shortwave over the Southeast United States.
This afternoon, the overwhelming majority of forecast models show a seaward track for Joaquin. Instead of reacting specifically to forecast model solutions, it is important to attempt to understand the synoptic setup and reasoning behind these changes.
What are the meteorological reasons for the change, and are they correct?
1) Most other models, for days, had been completely wrong in halting Joaquin’s southern movement north of the Bahamas. The majority of forecast models showed Joaquin turning west and north earlier and at a much further north latitude, which helped Joaquin to begin to feel the effects of the trough in the Southeast (the one that would pull it towards the coast) much quicker.
Once it drifts south of the trough, it starts to feel more westerly flow instead of southerly flow, and thus it turns a bit eastward. Run after run over the past few days, forecast models have trended southward with Joaquin’s position, in response to the tremendous blocking pattern in the Atlantic. Initially, the south corrections didn’t have an impact on the track of the surface low, as it still remained far enough north to feel the effects of the incoming trough. After a while, however, Joaquin reached its threshold of trekking so far south that it started to miss the effects of the trough, and escape seaward.
2) The European Model has so far, had a much better handle on the trough that is located in the Atlantic. Most other guidance has struggled to understand whether Joaquin will be tugged east by the Central Atlantic trough, or west by the incoming trough in the Southeast states. The European has so far led the way in understanding Joaquin’s movements and interactions with its surrounding features.
Despite the blocking pattern nearly matching the composite that sends hurricanes into the Eastern United States, there are several nuances in this pattern that could cause the storm to move seaward. And those are being exposed in the latest forecast model solutions.
What are the potential scenarios at this point?
Generally, two potential scenarios exist with Joaquin at this point. If the storm takes a farther west/northwest movement over the next 24 hours, most forecast models agree the influence from the incoming trough over the Southeast United States will be enough to pull the storm back toward the Mid Atlantic Coast. This would be a higher impact situation for all Eastern Seaboard residences.
The second scenario takes Joaquin farther south and east initially, and then northward — but it feels more influence from the trough in the Central Atlantic and starts moving more northeast. Since it does not interact with the trough over the Southeast States, it slips through a small “escape route” and heads out to sea. This is currently the scenario projected by an overwhelming amount of guidance, and would spare most areas any significant impacts or hazards.
What do I do now?
As it stands currently, confidence is growing that Joaquin will take a seaward track. That being said, impacts from the storm are still projected to be 72 to 84 hours from now, due to Joaquin’s meandering in the Bahamas. This leaves open a significant window for model adjustments. As we have seen in the past 12 to 24 hours, these adjustments can be rapid — and can change the forecast dramatically.
The best thing to do at this stage is remain prepared, and continue to monitor the forecast. We spoke yesterday about having a preparedness plan in place. That has not changed. Forecasters will continue to monitor Joaquin over the next 12 to 24 hours, as well as forecast models response to the storms behavior, and should have a much more confident idea as to where the storm is heading by Friday evening.