Forecasts Come into Focus for Caribbean Disturbance

Invest 97L to threaten Central America with heavy rain and flooding but stay south of Florida

For several days, forecast models have signaled possible tropical development in the western Caribbean by week’s end, but we’re now beginning to get a clearer picture of the system’s trajectory into the weekend.

The low-pressure area designated Invest 97L by the National Hurricane Center is sailing west to the south of Haiti this morning but remains a jumbled mess of disorganized storminess. Models were never enthusiastic about 97L’s development odds for the early to middle part of the week, as modestly strong wind shear from the north weighs heavy on the disturbance. By tomorrow and Friday, however, as 97L draws closer to Central America, our computer models expect wind shear to relax, which may allow the system to start tapping into some of the warmest Caribbean waters on record.

It remains to be seen how much 97L or what forms from it organizes in the short window before moving inland across Nicaragua or Honduras on Saturday. Our major global models have trended toward a weaker system, but intensity models say there’s opportunity for growth, with ample tropical moisture and ocean fuel ahead. Regardless of development, we anticipate the potential for very heavy rainfall, which could lead to flash flooding and dangerous mudslides from Nicaragua northward to parts of Belize over the weekend. Given the possibility of increasingly conducive conditions to strengthening on approach to land, interests in Central America should stay aware of the changing forecasts.

Model tracks for Invest 97L into next week. Our most reliable models move the disturbance or what forms from it inland between Nicaragua and Honduras over the weekend. Though a small handful of scenarios show a bend northward, models have largely settled on an outcome that keeps the system well south of Florida and the Gulf of Mexico next week. Credit: Clark Evans/University of Wisconsin-Milwaukee

For Florida and areas north, forecast models have largely settled on an outcome that drives 97L or any tropical cyclone that comes from it westward, with blocking high pressure preventing or limiting any northward progress into next week. While we’ll continue to follow forecast trends, for now the system looks to stay safely to our south.

Fall pattern settling in over Florida

We’ve reached the point in the hurricane season where fall fronts are progressing quickly enough through Florida to stave off routine tropical threats. While we still watch for any fronts loitering for too long over nearby waters, tropical trouble now becomes the exception, not the rule. With the jet stream migrating south for the winter, a curtain of powerful wind shear draws over the U.S., giving us reason to breathe a little easier as hurricane season winds down.