Tropics heating up: extreme uncertainty awaits

Good evening.

Before I start this post, I will now say I no longer (at least for the moment) live in the region, but I certainly will continue to blog for it. I’m attending Mississippi State University’s meteorology program now. So the Gulf storms are of greater interest for me (I’m about 5 hours inland, so my relative risk would be roughly equal to my previous location). That said, let’s forget the Gulf and think about the east coast, where most of our readers are, for a perspective on not one, not two, but THREE tropical systems.

Tropical Storm Fiona
Infrared satellite imagery of Tropical Storm Fiona at 7:15 pm EDT August 19, 2016.

Infrared satellite imagery of Tropical Storm Fiona at 7:15 pm EDT August 19, 2016.

Fiona is a weak tropical storm in the central Atlantic battling shear and dry air. That said, it does have strong convection although it remains quite sheared. With over 40 kt of wind shear nearby and significant dry air expected to persist for the next couple days, it is likely to weaken to a tropical depression by tomorrow and may completely dissipate over the next couple days. That said, if it survives, a more conducive environment does await south of Bermuda in the days to come. Most likely it will not have a direct impact on the east coast, but it is still worth watching.

Disturbance (Invest) 99-L

Some rather spooky model runs this afternoon have grabbed our attention here. It has not even developed into a tropical cyclone yet, but some models have suggested downright frightening solutions. It is EXTREMELY important to note that any storm that reaches the east coast would be 9 to 12 days away, which is essentially fantasyland for models. It is possible that this system may not even develop, or may get trapped in low latitudes. The NHC has given it a 50% chance of development by early next week, but with more conducive conditions expected, I would argue it is likely we will see Tropical Depression Seven, and eventually Tropical Storm (or Hurricane?) Gaston within 4 to 6 days. More imminently, it will likely be a considerable threat for much of the Caribbean, particularly the Leeward Islands, Puerto Rico and Hispaniola, next week.

GFS height anomalies at the 500mb level for August 29, 2016. Notice the strong ridge extending off the east coast, with a trough in the Midwest. Some models bring the trough in sooner.

GFS height anomalies at the 500mb level for August 29, 2016. Notice the strong ridge extending off the east coast, with a trough in the Midwest. Some models bring the trough in sooner.

The upper-level pattern actually well supports an east coast hit or close call. A strong ridge of high pressure is expected to park itself south of Atlantic Canada next week and remain there for most of the rest of August. The key question is whether a trough which is being shown by many models enters the picture. That could enable the storm to turn northward – and the timing becomes key. If this system remains weak, then it could just be trapped in very low latitudes due to a ridge in the southern Gulf of Mexico. Fiona may also have a role to play if it opens up a hole. Ensembles are consistent in such a scenario, but the placement is widely varied, ranging from over the western/central Gulf of Mexico to near Bermuda (with some models trapping it in the Caribbean).

Model suite of ensemble runs through 10 days for 99L, as of 2 pm EDT August 19, 2016.

Model suite of ensemble runs through 10 days for 99L, as of 2 pm EDT August 19, 2016.

Next African low: Invest 90-L to come?

The NHC has also tagged a third low, which has not yet been classified, for potential development next week. As no models have been run on it, it is too early to determine any potential it may have.

Conclusion

It is VERY early, make no mistake. Other than weakening Fiona which is likely no threat, none of these systems have even developed. Models beyond 7 days are notoriously unreliable and prone to jumping around with unlikely solutions. That said, there is some consistency here and the large-scale pattern is noteworthy. It is too soon to speculate to any good degree, but it is clearly hurricane season and we should always be prepared for anything.

Forecaster Craig Ceecee – @Ceecee_Wx

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