Tropical Storm Isaias

Tropical Storm Isaias (ees-ah-EE-ahs) developed 155 miles south of Ponce, Puerto Rico at 11 pm AST on Wednesday July 29, 2020. The tropical storm then quickly moved northwest over the Dominican Republic on Thursday July 30, 2020. As the center of Isaias emerged over open waters, the storm intensified to a Category 1 Hurricane. The hurricane continued moving towards the northwest through the Bahamas before weakening back to a tropical storm at 5 pm Saturday August 1, 2020. The forward speed of the storm slowed as it turned towards the north on Sunday, paralleling the east coast of Florida. By Monday August 3, 2020, Isaias began to increase its forward speed as it approached the Carolina coast. Isaias also intensified back to a Category 1 Hurricane with maximum sustained winds of 85 mph, making landfall near Ocean Isle Beach, NC at 11:10 pm. Isaias intensity weakened back to Tropical Storm strength as it forward speed increased to near 30 mph early Tuesday morning.

The center of Isaias passed about 65 miles west of New York City at 3 pm on August 4, 2020. Tropical storm force winds extended well east of the center of circulation. The highest sustained wind speeds ranged from 35 to 55 mph, with gusts 60 to 80 mph. These winds caused widespread wind damage across New York City, Long Island, Southern Connecticut, northeast New Jersey, and the Lower Hudson Valley. There was also a confirmed EF-1 tornado in Westport, CT around 1:40 pm. The highest rainfall totals were across the Lower Hudson Valley and northeast New Jersey with amounts dropping off considerably to the east. Isaias was moving north-northeast at 40 mph when it moved across the region.

Many archived reports below are courtesy of the Iowa State University Iowa State Mesonet (IEM)    National Weather Service Text Product Archive   .

•  Post Storm Report  (Updated Friday Aug 7 2020 6:13 PM)
•  Local Storm Report Summary  (See storm report section below for more details)
•  Isaias NHC Advisories 
•  Hurricane Local Statements 
•  Rainfall Totals Public Information Statement 
•  Peak Wind Gusts Public Information Statement 
•  Westport, CT EF-1 Tornado Preliminary Survey Results 
•  Tornado Watch Issued 7:20am EDT 
•  Tornado Warning #1: 1:38pm EDT 
•  Tornado Warning #2: 2:05pm EDT 
•  Tornado Warning #3: 2:49pm EDT 

The map below displays locations of Local Storm Reports. Click any circle on the map below to give more detailed information. A full summary of storm reports in the NWS New York, NY area can be found  HERE . Please note the reports in the graphic and the text summary do not represent all damage given the large number of trees and power lines that were felled across the region.

An animation of quick-moving Isaias as seen from GOES-East. This is true color imagery depicting clouds, land, surface water/ocean, and vegetation. Isaias's center of circulation moved over southeastern NY/Lower Hudson Valley, with drier air and some convection/thunderstorms across southern CT and LI. The animation begins at 11am and ends at 8:30 pm on August 4th 2020.

Below is a radar animation of Isaias beginning 8 am and ending at 7:30 pm on Tuesday, August 4, 2020.

Below is a National Weather Service KOKX Doppler Radar animation beginning 6:00 am and ending at 3:45 pm as Isaias rapidly moved north across the region. Tornado Warnings (red and purple polygons), Flash Flood Warnings (green polygons) and Special Marine Warnings (light blue polygons) are also displayed throughout the animation. Images created using GR2 Analyst.

Peak wind gusts occurred with Isaias between about noon and 6pm on August 4th. Peak wind gusts, shown below, occurred over Long Island and southeastern CT. Peak winds in the upper 70s were observed across central Long Island, with a maxiumum value of 78 mph reported at Farmingdale. A full list of peak sustained and max wind gusts can be found  here .

The graphic below is Multi Radar Multi Sensor (MRMS) 24 hour Quantitative Precipitation Estimate (QPE) using Gauge Adjusted Radar ending 2 am August 5th, 2020. The swath of highest totals occurred across eastern Pennsylvania up through northern New Jersey northward up through Upstate New York.  Rainfall amounts  dropped off considerably towards the east with portions of Eastern Long Island and Southeast Connecticut receiving a quarter inch or less.

The highest rainfall totals from Isaias occurred in the lower Hudson Valley of NY and northeastern NJ. 4.55 inches was measured by a Co-Op observer 1 mile North of Port Jervis, NY with 4.04 inches 2 miles Southwest of Ringwood, NJ, and 3.12 inches in West Milford, NJ. Central Park, NY observed 0.48 inches of rain and Islip, NY observed 0.14 inches of rain.

 Complete listing of rainfall totals 

A Flash Flood Watch was issued for New York City and parts of the lower Hudson Valley at 4 pm Sunday August 2, 2020. This was while Isaias was was developing off the eastern coast of Florida. Subsequently, the flash flood watch was expanded to include parts of southwestern CT on Monday August 3rd 2020.  A flood advisory was issued at 11:51 AM for Hudson, Passaic, Union, Bergen, Essex, Western Orange, Rockland Counties, and New York City.   There was one report of flooding in Hackensack, NJ at 2:25 pm with River Road closed at Kansas Road.

 An NWS damage survey  determined that an EF-1 tornado occurred in Westport, CT in Fairfield County. The tornado occurred from a discrete, low topped storm cell, moving north northwest from Long Island Sound and over Saugatuck Shores in Westport, CT. The cell produced a water spout over the Sound, that made landfall as an EF-1 tornado around 1:40 pm on August 4, 2020. A tornado warning was issued at 1:38 pm. The waterspout was captured on video by a private Meteorologist as it was moving towards Saugatuck Shores in Westport around 1:40 pm.

The tornado produced severe damage to a house on Surf Road, with the roof ripped off as well as portions of the second floor's supporting wall structure. This debris was tossed about 30-50 feet north on the property. The Town of Westport Fire Department provided photos below. In addition, the tops of several pine trees in the front and side yard were either sheared or snapped off. The tornado likely quickly lifted and possibly tracked north as a funnel cloud for another 1 to 2 miles, before dissipating. The funnel cloud could have touched down as a waterspout on the Saugatuck River, south of Route 1, based on an eyewitness report from S Compo Road in Westport, CT. Otherwise, downstream damage reports are inconclusive for tornado damage, but consistent with damaging 40 to 50 mph straight line sustained winds and 60 to 70 mph gusts observed between 2 pm and 5 pm across southwestern CT from Tropical Storm Isaias.

A  Coastal Flood Watch  was issued Monday August 3rd for most of the south shore of Long Island and NYC (Queens and Brooklyn). Coastal inundation values of 1-3 ft were expected from Isaias at the the time of high tide on Tuesday afternoon and evening. This was predicted to result in minor to locally moderate/major flooding at vulnerable locations across the south shore. The Coastal Flood watch was upgraded and expanded to a  Coastal Flood Warning  by Monday afternoon, to also include Staten Island, coastal Westchester County, northeastern NJ and all of southern CT, as well. Widespread coastal flooding was not observed with Isaias, thanks in part to the storm's peak surge arriving outside of astronomical high tide. In short, a matter of a few hours made a big difference with respect to shoreline impacts and inland inundation. However, as shown by the graphics below, Isaias did have a surge of nearly 4-5 feet at some locations (in green).

In additional high surf advisories and high rip current risks were also in effect leading up to and during the entire event.

 Buoy 44065 (New York Harbor Entrance) 

Lowest Barometric Pressure: 998.7 mb at 18:50 UTC (2:50 PM EDT) August 4, 2020

Peak Wave Height: 16.7 ft at 18:50 UTC (2:50 PM EDT) and 19:50 UTC (3:50 PM EDT) August 4, 2020

Peak Sustained Wind: 51 mph at 17:40 UTC (1:40 PM EDT) August 4, 2020

Peak Wind Gust: 72 mph at 17:40 UTC (1:40 PM EDT) August 4, 2020

 Buoy 44025 (30 NM South of Islip, NY) 

Lowest Barometric Pressure: 1003.5 mb at 18:30 UTC (2:30 PM EDT) August 4, 2020

Peak Wave Height: 20.0 ft at 18:50 UTC (2:50 PM EDT) August 4, 2020

Peak Sustained Wind: 51 mph at 18:10 UTC (2:10 PM EDT) August 4, 2020

Peak Wind Gust: 67 mph at 18:50 UTC (2:50 PM EDT) August 4, 2020

 Buoy 44017 (23 NM SSW of Montauk Point, NY) 

Lowest Barometric Pressure: 1008.3 mb at 19:40 UTC (3:40 PM EDT) August 4, 2020

Peak Wave Height: 16.4 ft at 22:50 UTC (6:50 PM EDT) August 4, 2020

Peak Sustained Wind: 38 mph at 19:10 UTC (3:10 PM EDT) August 4, 2020

Peak Wind Gust: 51 mph at 20:00 UTC (4:00 PM EDT) August 4, 2020

 Buoy 44040 (Western Long Island Sound) 

Peak Sustained Wind: 36 mph at 18:00 UTC (2:00 PM EDT) August 4, 2020

Peak Wind Gust: 63 mph at 18:00 UTC (2:00 PM EDT) August 4, 2020

 Buoy 44069 (Great South Bay) 

Peak Sustained Wind: 45 mph at 20:00 UTC (4:00 PM EDT) August 4, 2020

Peak Wind Gust: 58 mph at 20:00 UTC (4:00 PM EDT) August 4, 2020