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Tropical Tracker: Development areas expand in July, tropics quiet for now

Tropics could start to wake up by the middle of July

The yellow shaded areas are where tropical development typically occurs in the month of July.
The yellow shaded areas are where tropical development typically occurs in the month of July.

ORLANDO, Fla. – There’s still a long way to go, but we have made it through the first month of hurricane season (knock on wood). There are some indications, though things could heat up just a bit in the tropics by the middle of the month.

A little more dust coming

Our allergies and sinuses could use a break after the thick dust from the Sahara Desert blanketed Central Florida skies last week.

The dust has been thinning out over Central Florida, but is remaining persistent across the Atlantic Basin.
The dust has been thinning out over Central Florida, but is remaining persistent across the Atlantic Basin.

More dust is headed our way in the coming week, but it won’t be nearly as thick as what we dealt with last week. Maybe just maybe since the concentration of dust will be lower, our sunrises and sunsets will be better. Fingers crossed!

There’s enough dust in the middle of the Atlantic to keep tropical development relatively low. This doesn’t stop development altogether, but it does make it harder to get things going and we like that! Everything you need to know about the yearly-occurring phenomenon can be found here.

New places to look for development

In June, the prime areas to watch for tropical development are typically right off the Southeast Coast, the Gulf of Mexico and in the Caribbean. In July, the typical areas for tropical development expand out of the Caribbean and slightly beyond the Lesser Antilles.

The lines below represent the tracks of July-born storms since 1960. Notice the lines start to move a little further east.

All tropical storms and hurricanes in July since 1960.
All tropical storms and hurricanes in July since 1960.

The Cabo Verde season, storms developing off of Africa and moving over the Cabo Verde archipelago, gets underway in August.

Next two weeks

Indications are that after a nice quiet stretch in the tropics, we may try and ramp things up a little in the Atlantic.

Within the next week, don’t be surprised if something tries to develop off of the southeast coast of the United States. A couple of systems are likely to slide off of the U.S. and move over the warmer waters of the Atlantic. The systems prior to tropical development could increase rain chances in Central Florida, but any tropical/subtropical development would occur as it moves AWAY from Florida and will NOT be a threat to us.

There will be a chance for tropical/subtropical development around the end of the first week of July. Anything that develops will move AWAY from Florida.
There will be a chance for tropical/subtropical development around the end of the first week of July. Anything that develops will move AWAY from Florida.

By the middle of July, the atmosphere could become more conducive to thunderstorms rolling off of Africa. Climatologically speaking, storms coming off of Africa increase in August and September, but that can happen in July, albeit not as common.

Get to know the MJO

Similar to El Nino or La Nina, the oscillation known as the Madden-Julian Oscillation, or MJO can impact weather globally. The MJO is a disturbance of clouds and rain that makes a trip or several trips around the world during the spring and summer. When it comes to the tropics, the MJO can either enhance activity or suppress it.

The Madden-Julian Oscillation can enhance or suppress tropical development as the disturbance moves around the world. Diagram from climate.gov (NOAA)
The Madden-Julian Oscillation can enhance or suppress tropical development as the disturbance moves around the world. Diagram from climate.gov (NOAA)

This system of upward motion, enhanced storm activity and downward motion moves east around the globe every 30-60 days. When the Atlantic is under the influence of downward motion or sinking air, tropical development becomes less likely. When the convective or enhanced phase of the MJO sneaks into the Atlantic Basin, tropical development can become more likely.

MJO by second week of July. Storm activity could be enhanced near Africa by the middle of July. Unfavorable conditions persist closer to home.
MJO by second week of July. Storm activity could be enhanced near Africa by the middle of July. Unfavorable conditions persist closer to home.

There’s a lot of sinking air (brown) over the Western Atlantic so if something were to roll off of Africa in the middle of the month, it may have trouble developing. The unfavorable conditions may spread through the Atlantic for most of July, which would be a good thing for us!


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