BULLETIN
Tropical Storm Isaias Advisory Number 30…Corrected
NWS National Hurricane Center Miami FL AL092020
1100 AM EDT Tue Aug 04 2020
Corrected reference location to Fredericktown, Maryland
…CENTER OF ISAIAS MOVING RAPIDLY ACROSS EASTERN MARYLAND…
…STRONG WINDS…HEAVY RAINFALL…AND TORNADOES WILL CONTINUE TO
SPREAD NORTH-NORTHEASTWARD ALONG THE MID-ATLANTIC COAST TODAY…
SUMMARY OF 1100 AM EDT…1500 UTC…INFORMATION
———————————————–
LOCATION…39.1N 76.1W
ABOUT 20 MI…30 KM SSW OF FREDERICKTOWN MARYLAND
ABOUT 70 MI…110 KM SW OF PHILADELPHIA PENNSYLVANIA
MAXIMUM SUSTAINED WINDS…70 MPH…110 KM/H
PRESENT MOVEMENT…NNE OR 20 DEGREES AT 35 MPH…56 KM/H
MINIMUM CENTRAL PRESSURE…993 MB…29.33 INCHES
WATCHES AND WARNINGS
——————–
CHANGES WITH THIS ADVISORY:
The Tropical Storm Warning has been discontinued south of Duck,
North Carolina, including the Pamlico and Albemarle Sounds.
The Storm Surge Warning has been discontinued.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Tropical Storm Warning is in effect for…
* North of Duck North Carolina to Eastport Maine
* Chesapeake Bay
* 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 to 18 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 1100 AM EDT (1500 UTC), the center of Tropical Storm Isaias was
located by NOAA Doppler weather radars and surface observations
near latitude 39.1 North, longitude 76.1 West. Isaias is moving
toward the north-northeast near 35 mph (56 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 tonight.
Data from Doppler weather radars along with surface observations
indicate that maximum sustained winds remain near 70 mph (110 km/h)
with higher gusts. Only gradual weakening is anticipated while
Isaias moves north-northeastward near the mid-Atlantic coast today.
A faster rate of weakening is expected to begin tonight, and the
system 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. During the past hour, a sustained wind of 55 mph
(89 km/h) and a gust to 65 mph (105 km/h) were reported by a
Weatherflow site at Ocean City, Maryland. A sustained wind of 45
mph (72 km/h) and a gust to 57 mph (92 km/h) were reported at Ocean
City-South Beach, New Jersey.
The estimated minimum central pressure based on surface
observations is 993 mb (29.33 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.
STORM SURGE: The combination of storm surge and the tide will
cause normally dry areas near the coast to be flooded by rising
waters moving inland from the shoreline. The water could reach the
following heights above ground somewhere in the indicated areas if
the peak surge occurs at the time of high tide…
Ocracoke Inlet NC to the North Carolina/Virginia border including
Pamlico Sound, Albemarle Sound, Pamlico and Neuse Rivers…1-2 ft
North of the North Carolina/Virginia border to Martha’s Vineyard
including the Chesapeake Bay, the Tidal Potomac River, Delaware Bay,
Long Island Sound, Block Island Sound, Narragansett Bay, Buzzards
Bay, and Vineyard Sound…1-3 ft
The deepest water will occur along the immediate coast in areas of
onshore winds, where the surge will be accompanied by large waves.
Surge-related flooding depends on the relative timing of the surge
and the tidal cycle, and can vary greatly over short distances.
For information specific to your area, please see products issued
by your local National Weather Service forecast office.
WIND: Widespread tropical-storm conditions are expected in the
tropical storm warning area in the mid-Atlantic states, 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.