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Tropical Storm Isaias Intermediate Advisory Number 30A
NWS National Hurricane Center Miami FL AL092020
200 PM EDT Tue Aug 04 2020
...ISAIAS RACING NORTH-NORTHEASTWARD ACROSS EASTERN PENNSYLVANIA
INTO SOUTHEASTERN NEW YORK...
...STRONG GUSTY WINDS...HEAVY RAINFALL...AND THE THREAT OF
TORNADOES WILL SPREAD NORTHWARD INTO SOUTHERN NEW ENGLAND...
SUMMARY OF 200 PM EDT...1800 UTC...INFORMATION
ABOUT 65 MI...105 KM w OF NEW YORK CITY
MAXIMUM SUSTAINED WINDS...65 MPH...100 KM/H
PRESENT MOVEMENT...NNE OR 20 DEGREES AT 40 MPH...65 KM/H
MINIMUM CENTRAL PRESSURE...994 MB...29.35 INCHES
WATCHES AND WARNINGS
CHANGES WITH THIS ADVISORY:
The Tropical Storm Warning has been discontinued south of
Chincoteague, Virginia, and south of Smith Point in the Chesapeake
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Tropical Storm Warning is in effect for...
* North of Chincoteague Virginia to Eastport Maine
* Chesapeake Bay north of Smith Point
* Tidal Potomac River
* Delaware Bay
* Long Island and Long Island Sound
* Martha's Vineyard, Nantucket, and Block Island
A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area, in this case
within the next 12 hours.
For storm information specific to your area, including possible
inland watches and warnings, please monitor products issued by your
local National Weather Service forecast office.
DISCUSSION AND OUTLOOK
At 200 PM EDT (1800 UTC), the center of Tropical Storm Isaias was
located by NOAA Doppler weather radars and surface observations near
latitude 40.9 North, longitude 75.1 West. Isaias is moving toward
the north-northeast near 40 mph (65 km/h), and this general motion
accompanied by some increase in forward speed is expected through
tonight. On the forecast track, the center of Isaias will continue
to move near or along the coast of the mid-Atlantic states today,
and move across the northeastern United States into southern Canada
Data from Doppler weather radars along with surface observations
indicate that maximum sustained winds have decreased to near 65 mph
(100 km/h) with higher gusts. Only slow weakening is expected this
afternoon, followed by a faster rate of weakening tonight. Isaias
is forecast to become post-tropical tonight or early Wednesday.
Tropical-storm-force winds extend outward up to 140 miles (220 km)
from the center. The New York Harbor Entrance buoy (44065) recently
reported a sustained wind of 56 mph (91 km/h) and a gust to 72 mph
The estimated minimum central pressure based on surface
observations is 994 mb (29.35 inches).
HAZARDS AFFECTING LAND
Key messages for Isaias can be found in the Tropical Cyclone
Discussion under AWIPS header MIATCDAT4, WMO header WTNT44 KNHC,
and on the web at www.hurricanes.gov/text/MIATCDAT4.shtml.
WIND: Widespread tropical-storm conditions are expected in the
tropical storm warning area in the mid-Atlantic states and
southern New England, including portions of the Chesapeake Bay
region today, with wind gusts to hurricane force possible. These
winds could cause significant tree damage and power outages.
Tropical storm conditions are expected to reach southern New
England this afternoon and northern New England tonight.
Gale-force winds are expected to spread into southeastern Quebec
tonight and Wednesday. See products issued by Environment
Canada for more information.
RAINFALL: The following rainfall accumulations are expected along
and near the track of Isaias:
Central and Northern Mid-Atlantic: Additional 2 to 4 inches,
isolated maximum storm totals of 8 inches.
Eastern New York into Vermont: 2 to 4 inches, isolated maximum
totals 6 inches.
Western Connecticut, western Massachusetts, New Hampshire and
western Maine: 1 to 3 inches.
Heavy rainfall along the East Coast, near the path of Isaias, will
result in flash and urban flooding, some of which may be significant
in the mid-Atlantic and Northeast through tonight. Potentially
life-threatening urban flooding remains possible Philadelphia, and
elsewhere along and just west of the I-95 corridor today. 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 river flooding.
TORNADOES: A few tornadoes are possible across northern New Jersey
and southeastern New York, through southern New England, by late
afternoon. A risk for tornadoes may continue across northern New
England through this evening.
SURF: Swells generated by Isaias will spread northward along the
mid-Atlantic and Northeast coasts of the United States today. These
swells are likely to cause life-threatening surf and rip current
conditions. Please consult products from your local weather office.
Next complete advisory at 500 PM EDT.