Hurricane Matthew continues to churn in the Caribbean this morning, and after briefly obtaining Category 5 strength this weekend, has steadily maintained Category 4 strength with winds near 145 miles per hour. Matthew was the first Category 5 hurricane in the Atlantic Ocean in 9 years, making the storm significant in its own right before it made any landfall. But exactly where the storm tracks over the next several days will determine its legacy — and some forecast models continue to suggest that we may remember the storm for a landfall on U.S soil.
The pattern dictating where Matthew goes, however, is complicated. As it stands this morning, steering currents around Matthew are quite weak. They’ve been that way for a few days now, and not surprisingly Matthew has lingered, wobbled, and meandered in the warm waters of the Central Caribbean. He will begin a notable northward turn today, however, and as he moves northward toward more favorable mid and upper level winds, the storm is expected to pass dangerously close to the islands of Jamaica, Haiti, and Cuba. Forecast models currently suggest Matthew is most likely to track on the Eastern Shores of Cuba before re-emerging into the borderline hot waters of the Bahamas.
Here, the forecast becomes much more uncertain. Much of the uncertainty will depend on the forward speed of the storm, and global forecast models (and their ensembles, for the most part) are struggling to determine how fast the storm will track. The European model, most notably, lingers Matthew in the Bahamas for much longer than any other model, while the GFS suite is quicker to move the storm northwestward towards the Southeast United States Coast.
The northwestward movement is supported by the presence of a Western Atlantic Ridge, more affectionately known as a “WAR”. This feature remains in place this week, as a ridge builds over the Eastern United States as well, essentially “blocking” Matthew’s path out to sea. The storm is steered to the northwest, then, and remains in the proverbial bathwater of the Bahamas. Favorable mid and upper level shear patterns may also allow the storm to strengthen during this time as it drifts precariously close to the coasts of Florida, Georgia, and the Carolinas.
Seem complicated enough? The forecast gets even more complicated past the mid-way point of this week. The GFS and its ensemble suite have been consistently indicating the presence of an aggressive mid level trough and upper air system, moving through the Central United States during the middle part of the week. This feature slides eastward toward the Ohio Valley and eventually East Coast by weeks end. This idea spells trouble for East Coast interests monitoring Matthew, as it could interact and phase with the storm system, tugging it back towards the coasts — particularly in New England.
But the European suite (and, for arguments sake, the CMC and Ukmet as well) suggest that aforementioned Central US system will be much weaker and more poleward in nature, i.e not as amplified and strong. Matthew, in that case, would simply meander off the Southeast Coast until the “WAR” discussed earlier slightly weakens, at which point the storm would escape seaward while a weak trough passes harmlessly through the Northeast United States.
As you might imagine, this leaves meteorologists in a bit of a pickle. One big takeaway is that the speed of the system has a large impact on the forecast. A faster Matthew track means interaction with the aforementioned system is more likely, while a slower track (similar to the European suite) would suggest that the trough passes harmlessly through, regardless of strength. Another is the fact that disturbances overall have trended more progressive over the United States over the past few months, lending credence to the Europeans idea of a less amplified pattern overall.
Over the next 24 hours, increasing amounts of data ingestion into forecast models should begin to give us a better idea as to how the system will behave. Trends in forecast model guidance and their ensembles will begin to aid in rising confidence as Matthew emerges into the Bahamas by the middle part of the upcoming week. For now, hang tight, continue to monitor forecasts, and enjoy the ridge of high pressure building into the Eastern US which should provide relatively benign weather through the weeks end.