Little change today re: tropics and east coast situation

Good evening.

I’ve been following the tropical situation closely involving all three systems (ex-Fiona, Gaston and 99L) and there is one thing that can clearly be stated. It appears that the threat for the Northeast and Mid-Atlantic right now – at least from direct impacts – is very low. Hopefully by the weekend, we may have enough confidence to make forecasts, but for now it remains a situation of watching and waiting. Of the three storms, the one that has yet to get a name is the one of greatest interest. Make no mistake, any landfall possibilities and forecasts are very premature. The first US impacts are at least 5 days away, while any Northeast impact is at least 8 days away. That is, if there are even any such threats.

Current satellite image of the broader Atlantic (image from NHC/NCDC) annotated showing current systems as of 8:30 pm EDT August 23, 2016.

Current satellite image of the broader Atlantic (image from NHC/NCDC) annotated showing current systems as of 8:30 pm EDT August 23, 2016.

Remnants of Fiona

Tropical Depression Fiona quietly degenerated into a remnant low this morning as deep convection was largely lacking. Although there is limited convection, few models redevelop this system back into a tropical cyclone. The forecast is for it to meander across the western Atlantic and open up into a weak trough soon. It shouldn’t affect land before completely dissipating.

Tropical Storm Gaston

Gaston has slowly intensified today, although the rate of development has slowed since this morning. Currently, Gaston is located west-southwest of the Cabo Verde islands, with sustained winds estimated at near 65 mph. Continued intensification is likely and it should become a hurricane in the next 12 to 24 hours. The storm should remain well offshore as it recurves well east of Bermuda (most models agreed there). There is a chance that Gaston could become a major hurricane in the next few days.

Disturbance/Invest 99L

This system has most of our attention spans focused on it. As of now it is a vigorous tropical wave with a weak low pressure area associated with it. The NHC estimates that there is a 70% chance of development into a tropical cyclone in the next 5 days (most likely by Friday) which appears reasonable to me. Depending on land interaction with the larger Caribbean islands, that may be accelerated or delayed. It should also become Tropical Storm Hermine by the weekend. Fortunately, the models keep this system away from the Northeast due to the presence of a strong ridge over the east coast, which will likely either force this westward into the Gulf of Mexico, or northward into an opening east of the ridge (less likely). Confidence is quite high in that as models are virtually unanimous on the ridge holding firm.

What the models say: the next week
ECMWF model run (12Z August 23) for next Tuesday morning (7 days out) showing surface pressures of 500mb heights. The ridge is very strong, forcing the low (at the time Tropical Storm Hermine) westward towards the western Gulf coast.

GFS model run (18Z August 23) for next Tuesday afternoon (7 days out) showing surface pressures of 500mb heights. The ridge is very strong, forcing the low (at the time Tropical Storm Hermine) westward towards the western Gulf coast.

ECMWF model run (12Z August 23) for next Tuesday morning (7 days out) showing surface pressures of 500mb heights. Notice Hurricane Hermine over the northeast Gulf coast, which this model suggests makes landfall on the Florida Panhandle. It is far too soon to say for sure that is likely or even more than just a distinct possibility.

ECMWF model run (12Z August 23) for next Tuesday morning (7 days out) showing surface pressures of 500mb heights. Notice powerful Hurricane Hermine over the northeast Gulf coast, which this model suggests makes landfall on the western Florida Panhandle. It is far too soon to say for sure that is likely or even more than just a distinct possibility.

Although it is far too early to be certain, it appears that the keys to this puzzle are the strong ridge (which the GFS holds firm on while the ECMWF breaks up), as well as shear, dry air and land interaction. The GFS, its derivatives (HWRF, GFDL) and some of its ensembles keep the system weak, while the European model rapidly intensifies it off the Florida coast. But we don’t even know if it will even develop, as it will be interacting with Puerto Rico and Hispaniola over the next couple days.

Conclusion

We should know more in the days ahead. Stay tuned, but don’t panic or get carried away, if you are in the Southeast or have friends or family there. As for the Northeast, it appears there are no imminent threats. However, with tropical weather sitting in the Atlantic basin, we can’t let our guard down. Just make sure you choose your sources correctly – trusted local and national meteorologists are your best bets. Any impact to land is at least a few days away, and even that is not guaranteed.

Forecaster Craig Ceecee – @Ceecee_Wx

Leave a Reply