The National Weather Service is warning Greenwich residents to prepare for severe thunderstorms on Tuesday, July 21, with flash flooding possible and storms expected to roll through in waves from morning into the night.
The NWS office in New York issued a Hazardous Weather Outlook for Southern Fairfield County on Monday, July 20, forecasting multiple rounds of showers and thunderstorms from Tuesday morning through Tuesday evening with potential for scattered severe storms and flash flooding.
The NWS local forecast for Greenwich calls for thunderstorms throughout Tuesday, with a high near 80 degrees, southeast winds gusting up to 21 mph, and up to a half-inch of rain during the day. The heaviest activity is expected Tuesday night, when the chance of precipitation rises to 80 percent and an additional half to three-quarters of an inch could fall.
No formal watch or warning had been issued for Fairfield County as of Monday evening. Watches and warnings may be issued closer to the event as conditions develop; residents should monitor for updates.
Regional threats
The Storm Prediction Center placed parts of Pennsylvania, Maryland, and northern Virginia under an Enhanced Risk — the third level on its five-point scale. Connecticut falls in a lower risk category. In the Enhanced Risk zone, AccuWeather said storms could produce wind gusts up to 75 mph. The NWS said the atmosphere could support supercells and bowing lines of thunderstorms across the region, with a few tornadoes possible where supercells remain organized.
Flash flooding is also a concern where storms repeatedly move across the same communities.
A strong cold front pushing into warm, humid air is driving the pattern. Lingering showers are possible on Wednesday, July 22, before drier conditions arrive Thursday, July 23.
What to do
In guidance issued ahead of a separate storm on Friday, July 18, Greenwich Emergency Management Director Joseph Laucella's office advised residents to charge phones, clear storm drains and gutters if safe to do so, and have multiple ways to receive weather alerts. The department also urged residents never to drive through flooded roads and to stay away from downed trees and power lines.
Residents can sign up for Greenwich Alerts, the town's emergency notification system, at GreenwichAlerts.org, by texting "Greenwich" to 888-777, or by downloading the Everbridge app. Eversource customers can report outages online or by calling 800-286-2000.
In an emergency, dial 911. Greenwich Emergency Management can be reached at 203-637-7505, ext. 206.
