Potential Tropical Cyclone 16 earned the name Nana yesterday afternoon after Hurricane Hunters found a closed center of circulation under the system’s cluster of thunderstorm activity. The initial Hurricane Hunter pass found a very small eyewall, prompting come concern that the storm might rapidly intensify. However, additional recon observations today show that the storm’s initial small core has dissipated, leaving a larger/broader circulation in its place. It’s a lot harder for larger storms without an already-consolidated inner core to spin up really quickly. As a result, rapid intensification now seems unlikely.

One other factor that will limit Nana’s potential for intensification is northerly wind shear from an upper-level low located near Jamaica. This shear is pushing most of Nana’s intense thunderstorm activity to the south of the storm’s center which will make any strengthening that does occur between now and landfall relatively modest.

The official NHC forecast is more or less unchanged since yesterday, and calls for modest strengthening in the next 18 hours before landfall in central or southern Belize. Whether or not Nana comes ashore as a 65-70 mph tropical storm or a 75 mph hurricane is mostly an academic distinction. The expected impacts from Nana include dangerous storm surge, heavy rain and associated flooding/mudslide threats, and strong winds/associated power outage and minor structural damage threats.

Nana will dissipate quickly over the mountains of Guatemala and southern Mexico tomorrow afternoon/evening.

-Jack

Posted on 9/2/2020 by Jack Sillin with the Hurricane Tracker App. These posts are meant to provide our users with a detailed analysis of the tropics as conditions warrant and may not be updated on a daily basis. For the latest up to date storm information, always go to “Current Storms” and select a system for the latest information.

We will have another tropical weather discussion as conditions warrant. Thanks for using Hurricane Tracker.

There are three tropical entities to watch in the Atlantic this morning: Tropical Depression Fifteen (just off Cape Hatteras), newly formed Tropical Storm Nana in the Caribbean, and a disorganized wave within the monsoon trough near Africa. Despite being closest to the US coastline and the only storm to be officially designated as a tropical cyclone, TD 15 is the system we have to worry least about this week. It may or may not grab the name “Nana” as it moves east-northeast into the open North Atlantic, but the presence or absence of 40 mph sustained winds is mostly trivial. The cyclone will dissipate later this week as it interacts with a stalled frontal boundary and moves over cooler waters.

As far as impacts from newly formed Tropical Storm Nana are concerned, the primary one will be flooding rain in Central America. Honduras, Belize and Guatemala are likely to see very heavy rain as Nana moves towards the Yucatan Peninsula. With steep terrain and limited infrastructure, this region is extremely vulnerable to flooding issues even from a “weak” tropical storm.

A strong mid-level ridge of high pressure will keep Nana moving almost due west this weekend so while we can’t totally rule out continued development in the Bay of Campeche, it looks unlikely unless the system’s track shifts unexpectedly to the north.

In the far eastern Atlantic, the monsoon trough is quite active thanks to a combination of seasonal and intraseasonal influences. The big question is to what extent can all that thunderstorm activity coalesce into a single system. This is a really tough question to answer, and the strong dependence of the medium-range forecast on random convective interactions in the near-term is giving models quite a bit of difficulty. I think we’re likely to see some sort of system organize in the eastern Atlantic this week, but whether that’s a broad tropical storm or a developing hurricane, it’s just too early to say. We’ll be keeping a close eye on this system over the coming week and will keep you updated with the latest as we know more.

Posted on 9/1/2020 by Jack Sillin with the Hurricane Tracker App. These posts are meant to provide our users with a detailed analysis of the tropics as conditions warrant and may not be updated on a daily basis. For the latest up to date storm information, always go to “Current Storms” and select a system for the latest information.

We will have another tropical weather discussion as conditions warrant. Thanks for using Hurricane Tracker.

Tropical Storm Nana Expected to Make Landfall in Belize as a Hurricane Tomorrow

Tracking Tropical Depression 15 and Newly Formed Tropical Storm Nana