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Eastern Atlantic Still Active

Posted by Andy Johnson under Daily updates

This year is already the 6th most active Atlantic hurricane season on record. Officially, hurricane season continues until November 30. In some rare cases, December hurricanes have been observed. It is very unlikely we would break the all-time record of 28 named storms  set in 2005 but we could end up being in the top 5 most active seaseons before 2010 is over.

Oddly enough, the eastern Atlantic continues to be fairly active this late into October. Usually, in late October and November our focus is on the western Atlantic, Gulf of Mexico and Caribbean Sea for tropical development.  Invest 90L is fairly far to the north in the eastern Atlantic and will be encountering cooler temperatures over the next few days. However, convection has become more circular in appearance today and the NHC gives the system a 30% chance of becoming a tropical cyclone in the next 48 hours. Steering currents are very weak so Invest 90L is nearly stationary. The light shear could allow some development.

Invest 91L developed today and is located further south than Invest 90L  Invest 91L is over warmer waters than 90L and shear is also low over 91L . Some of the longer range models have 90L becoming a tropical depression or storm by the first part of next week. One scenario has the system moving into northern South America and another scenario would be for the system to intensify more over the central Caribbean.

A third system northeast  of the Leeward Islands is associated with an upper level low interacting with a surface trough. Over the next few days, this system could build downward in the atmosphere and potentially become a subtropical depression or storm.

The satellite image below is a closer view of the trio in the Atlantic. The moisture field around Invest 91L has increased quite a bit today. Notice the stream of moisture connected all the way back to another tropical wave getting ready to exit Africa in the Sahel region.

The GFS model shown below is valid at Friday at 8:00 PM. There is a large high pressure area north of Invest 90L  which will block recurvature in the near term. The GFS strengthens the subtropical low more than Invest 90L north of Hispaniola by Friday night.

The longer range GFS model valid Tuesday morning is shown below. By then, it has Invest 90L recurving into the northern Atlantic and the subtropical low weakening. Invest 91L is shown as a possible depression north of Venezuela.