Tropical Storm Isaias Wreaks Havoc Update One

000

WTNT44 KNHC 042057

TCDAT4

Tropical Storm Isaias Discussion Number  31

NWS National Hurricane Center Miami FL       AL092020

500 PM EDT Tue Aug 04 2020

NOAA Doppler radar data from Islip, New York (KOKX), indicated 

70-kt winds just off the surface south of Long Island earlier this 

afternoon, along with buoy reports from New York Harbor Inlet 

(44065) that supported lowering the intensity to 55 kt, so that 

value is used for this advisory.

The motion remains north-northeastward or 020/35 kt. Isaias will 

continue moving north-northeastward through tonight, accompanied by 

a gradual decrease in forward speed. In 12 hours or, the cyclone is 

expected to interact with a larger extratropical over southeastern 

Canada and degenerate into a post-tropical cyclone near western 

Maine. By 24 hours, Isaias is expected to transition to an 

extratropical low, and dissipate or become absorbed by the 

aforementioned larger extratropical low. The new NHC track forecast 

is just an extension of the previous advisory, and lies very close 

to the tightly clustered consensus track models.

Isaias will continue to gradually spin down and lose its tropical 

characteristics. The precipitation has decreased in size and also 

has become more stratiform in appearance, which are indications that 

the cyclone is gradually weakening. This downward trend should 

continue until Isais becomes an extratropical low in 12-24 hours.

There also remains a risk of tornadoes across portions of New 

England this afternoon and evening

Key Messages:

1. Tropical storm force winds that could cause tree damage and power 

outages will continue to spread across New England tonight.

2. Heavy rainfall near the path of Isaias, through the Hudson River 

Valley, is likely to result in flash flooding, particularly through 

urban areas and the surrounding terrain of the Catskills, Adirondack 

and Green Mountain Ranges through Tuesday night. Scattered minor to 

moderate river flooding is likely across portions of the 

Mid-Atlantic. Quick-responding rivers in the Northeast will also be 

susceptible to minor and possible moderate river flooding.

3.  The threat of tornadoes will spread into New England this 

afternoon and evening.

FORECAST POSITIONS AND MAX WINDS

INIT  04/2100Z 42.7N  74.2W   55 KT  65 MPH

 12H  05/0600Z 46.3N  72.4W   35 KT  40 MPH...POST-TROP/INLAND

 24H  05/1800Z 50.7N  71.1W   30 KT  35 MPH...POST-TROP/EXTRATROP

 36H  06/0600Z 53.3N  70.0W   25 KT  30 MPH...POST-TROP/EXTRATROP

 48H  06/1800Z 54.1N  67.8W   20 KT  25 MPH...POST-TROP/EXTRATROP

 60H  07/0600Z...DISSIPATED

$$

Forecaster Stewart