• Jackson Dill

Tropical Storm Isaias to Slam Connecticut Tuesday

Updated: Aug 4, 2020

Tropical Storm Isaias, currently located off the coast of South Carolina, is set to make landfall there later this evening or early Tuesday morning as a low-end, Category 1 hurricane. After landfall, however, the storm doesn't just disappear. Connecticut and the remainder of the U.S. East Coast will need to watch this storm tonight through Wednesday for significant impacts. Below, I will break down what this means for you in southwestern Connecticut.

Source: National Hurricane Center/NOAA


Isaias will move over land tonight, which typically indicates weakening, and slight weakening should occur, but that will mark the start of the gradual transition to it becoming an extratropical cyclone instead of a tropical cyclone. There are several technicalities to this identification but one of the qualities of this transition is the expansion of the cyclone's wind field. We've seen this in storms like Hurricane Sandy in 2012 -- I'm not saying this will be a Sandy but this storm did transition from hurricane or tropical cyclone status into an extratropical cyclone just before making landfall on the New Jersey coast.

Typically with tropical cyclones, like Isaias, they tend to curve out to sea when nearing the Southeast or after making landfall in this region. This storm, however, will track inland and over the I-95 corridor of the Mid-Atlantic and Northeast. This is thanks to the storm being wedged between two upper-level features: a dome of high pressure near Bermuda off to the east and a digging trough of low pressure to its west. These two will work in conjunction to steer Isaias to the north-northeast, affecting millions of people across the Northeast.


Rainfall: A few showers will begin during the wee hours of Tuesday morning. Then during the daylight hours of Tuesday morning, we will be on the eastern edge of the rain and thunderstorms, so it is possible it will be a washout of a morning for western towns while eastern towns are rather dry across southwestern Connecticut. By the afternoon, everyone will definitely get in on the rain, however. The heaviest of rain will happen during this time period, and a storm total of 2-4 inches of rainfall is expected.

This heavy rain will be associated with the core of the storm tracking nearby as well as the intense rising motion in the atmosphere. The storm will lie under the right entrance region of a jet streak in the upper-level trough, which leads to enhanced lift in the atmosphere and therefore heavy rain.

GFS model depicting jet stream winds. Source: WeatherBELL

The area has been dry but this may be too much rain in too short of a time, promoting some flooding or ponding. By the late-evening hours of Tuesday, the rain should come to an end as dry air funneled in on the backside of Isaias.

Wind: I think wind will be the biggest issue. This has to do with the track of the storm. Assuming Isaias follows the track expected, Connecticut will fall just east of the storm's center, which is where the strongest of winds will be located. These intense winds will take place between 12 and 6pm, which is when winds may gust as high as 45-60 mph inland and 50-70 mph at the coast. Hence the Tropical Storm Warning issued. The National Hurricane Center gives our area a 76% chance for winds of at least 39 mph and a 25% chance for wind of at least 58 mph, which are known as severe winds. Scattered to widespread power outages are anticipated due to these winds taking down branches and trees, so prepare for this!

Storm surge: Coastal water inundation won't be an issue for inland locations but along and near the immediate coastline, the National Hurricane Center is forecasting 1-3 feet of storm surge, especially in the afternoon and evening on Tuesday.

Tornadoes: Tornadoes are quite uncommon in our area, but with most tropical cyclones they are a threat due to the change in wind direction with height. Therefore, an isolated tornado will be possible during the latter half of the day Tuesday.

Stay safe with this storm and follow me on Twitter @Jackson_Dill for updates throughout the day on this storm.




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©2021 by Jackson Dill