SINT MAARTEN/CARIBBEAN – Crown Weather reported that based on the long-term weather model forecasts at this point in time, we could see some possible tropical development after mid-July and that things could get very busy for the months of August and September.
Crown Weather: “No tropical development is expected across the Atlantic, Caribbean and Gulf of Mexico for at least the next week or two. Beyond July 10th or so, the chances of tropical development may increase and we could very well see a named storm sometime during mid or late July.
“Over the next couple of weeks or so, the combination of widespread strong wind shear, bouts of dry, dusty Saharan Air and being in the downward motion pulse of the Madden Julian Oscillation will make conditions unfavorable for tropical development.
“All of this looks to change by the middle part of July as the background state across the Atlantic Basin will become more favorable for tropical development during mid and late July.
“An upward motion pulse of the Madden Julian Oscillation will begin to push into the Atlantic Basin during the first couple of weeks of July. This upward motion pulse will help to make things favorable for thunderstorm development, tropical disturbance development and a higher risk for tropical development from about mid-July through at least early August.
“In addition to this, the GFS ensemble guidance and the CFS model guidance are forecasting that wind shear may decrease during the second half of July leading to a more favorable environment for tropical development.
“There are two areas that I think that we are going to have to watch for possible tropical development during the second half of July –
“The first area is the area near the US Southeast Coast or near the northern US Gulf Coast. There have been a fair number of storm systems that have either formed in the northern Gulf of Mexico and moved up the US East Coast or formed along the US East Coast over the past several weeks. This leads me to believe that at some point an old front will help to spin up a tropical system between the US Southeast Coast and the northern US Gulf Coast, especially if the wind shear conditions decrease like some of the guidance suggests.
“The second area that I think that we need to watch for possible tropical development during the second half of July is the area from the coast of Africa to the Lesser Antilles. The tropical waves that have pushed off of the coast of Africa over the last couple of months have been quite robust. In fact, a very robust tropical wave is now located to the south of the Cape Verde Islands.
“Tropical development is not expected from this tropical wave due to increasingly unfavorable environmental conditions. I do have concerns that once the environmental conditions become more favorable later in July that we could definitely see a tropical system spin up between the Lesser Antilles and the coast of Africa.
“With all of that said, the latest very long range CFS model, which has a forecast out to 3 months in advance, shows the lid on tropical development staying on through the month of July, but that lid coming off as we enter the month of August. In fact, the CFS model is hinting at a very active August and September in terms of tropical storm/hurricane activity. Two things I want to note about this –
(1) Model guidance forecasts 3 months in advance should be taken with a grain of salt & the model will never get the exact details of the weather right. With that said, it should be noted that the model is showing the potential for a very active August and September and that is something that needs to be watched.
(2) Even though the CFS model currently does not show any sort of tropical development through the entire month of July, it does throw us hints that we should still watch things during those last 2 weeks or so of July.
“Bottom line is that tropical development looks unlikely through at least July 10. Beyond this, tropical development chances look to increase during the July 15 to August 1 time period in two areas – (1) from the Southeast US coast to the northern Gulf of Mexico and (2) across the area from the Lesser Antilles to the coast of Africa. Finally, August and September could be very, very active in terms of tropical activity across the Atlantic Basin.”