Tropical Depression Eight has intensified into Tropical Storm Gert. Meanwhile, the tropical wave near the Cabo Verde Islands we mentioned in our update Friday is now Invest 91L, and has potential to develop.
Tropical Storm Gert
As of the 10pm EDT advisory Gert was located in the Western Atlantic, well north of the Bahamas, moving north-northwest at 9mph with maximum sustained winds of 45mph and a minimum central pressure of 1009 millibars.
Forecast for Gert: Gert will strengthen some over the next day or two — likely making a run at hurricane status — but will take a path out to sea, posing no threat to the United States.
Invest 91L
Satellite images this evening indicate that Invest 91L has a very modest amount of unorganized, deep convective activity. They also show that it has some broad pronounced “spin” or vorticity, which is confirmed by data from CIMSS.
Chance of Development: Environmental conditions appear generally favorable for some development of 91L over at least the next five days.
Upper-level winds are conducive for development all the way from the Africa to the lesser Antilles; sea surface temperatures are supportive of tropical cyclone development throughout the entire main development region (MDR); and the environment in the vicinity and ahead of 91L is fairly moist, with the southern extent of the Saharan Air Layer (SAL) positioned well north of 91L.
However, despite the aforementioned environmental conditions, any development of 91L will be gradual, with significant organization unlikely to occur until the middle of this week at the earliest. This is because 91L is very large in size, and is also expected to merge with an area of low pressure associated with the monsoon trough on Tuesday or Wednesday, causing any consolidation to be slow.
In their 8pm EDT tropical weather outlook the National Hurricane Center gave 91L a 10% chance of developing over the next two days and a 40% chance of developing over the next five days.
Model Guidance: All three of the reliable global models used for predicting tropical cyclone genesis (the ECMWF, GFS, and UKMET) forecast development of 91L.
Additionally, all of the ECMWF ensemble members are forecasting development of 91L, along with many of the GFS ensemble members.
Forecast Track: A ridge of high pressure will steer 91L west/west-northwest, towards the Lesser Antilles, over the next five days; it is too early to determine where 91L will ultimately track in the long-term.
Forecast Intensity: If Invest 91L does develop, it is to early to speculate on how strong it might become.
___
For future updates follow us on our social media:
You can also follow our hurricane Facebook page Hurricane Central, or our partner page Daimien’s Gulf Coast Atlantic/Pacific Hurricane Tracking Center.
