Tropical Storm Isaias Advisory Number 24
NWS National Hurricane Center Miami FL AL092020
1100 PM EDT Sun Aug 02 2020
...ISAIAS EXPECTED TO BE NEAR HURRICANE STRENGTH WHEN IT REACHES
THE CAROLINAS...
SUMMARY OF 1100 PM EDT...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...28.5N 79.8W
ABOUT 50 MI...80 KM E OF CAPE CANAVERAL FLORIDA
ABOUT 365 MI...585 KM S OF MYRTLE BEACH SOUTH CAROLINA
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H
PRESENT MOVEMENT...NNW OR 345 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...995 MB...29.39 INCHES
WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:
The Tropical Storm Warning has been extended northward to Fenwick
Island Delaware, including Pamlico and Albemarle Sounds. A
Tropical Storm Warning has also been issued for the Chesapeake Bay
from Smith Point southward.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Storm Surge Warning is in effect for...
* Edisto Beach South Carolina to Cape Fear North Carolina
A Storm Surge Watch is in effect for...
* Cape Fear to Duck North Carolina
* Pamlico and Albemarle Sounds
A Hurricane Watch is in effect for...
* South Santee River South Carolina to Surf City North Carolina
A Tropical Storm Warning is in effect for...
* Sebastian Inlet Florida to Fenwick Island Delaware
* Pamlico and Albemarle Sounds
* Chesapeake Bay southward from Smith Point
A Tropical Storm Watch is in effect for...
* Fenwick Island Delaware northward to Watch Hill Rhode Island
* Chesapeake Bay north of Smith Point
* Tidal Potomac River
* Delaware Bay
* Long Island and Long Island Sound
Interests elsewhere along the northeast coast of the United States
should monitor the progress of Isaias. Additional watches or
warnings may be required tonight or early Monday.
A Storm Surge Warning means there is a danger of life-threatening
inundation, from rising water moving inland from the coastline,
during the next 36 hours in the indicated locations. For a depiction
of areas at risk, please see the National Weather Service Storm
Surge Watch/Warning Graphic at hurricanes.gov. This is a
life-threatening situation. Persons located within these areas
should take all necessary actions to protect life and property from
rising water and the potential for other dangerous conditions.
Promptly follow evacuation and other instructions from local
officials.
A Storm Surge Watch means there is a possibility of life-
threatening inundation, from rising water moving inland from the
coastline, in the indicated locations during the next 48 hours.
A Hurricane Watch means that hurricane conditions are possible
within the watch area. A watch is typically issued 48 hours
before the anticipated first occurrence of tropical-storm-force
winds, conditions that make outside preparations difficult or
dangerous.
A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area, generally within 36
hours.
A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area, generally within 48 hours.
For storm information specific to your area in the United
States, including possible inland watches and warnings, please
monitor products issued by your local National Weather Service
forecast office. For storm information specific to your area
outside of the United States, please monitor products issued by
your national meteorological service.
DISCUSSION AND OUTLOOK
----------------------
At 1100 PM EDT (0300 UTC), the center of Tropical Storm Isaias was
located by an Air Force Hurricane Hunter aircraft near latitude 28.5
North, longitude 79.8 West. Isaias is moving toward the
north-northwest near 9 mph (15 km/h), and this general motion is
expected to continue through tonight. A turn toward the north and
north-northeast along with an increase in forward speed is
anticipated on Monday and Tuesday. On the forecast track, the
center of Isaias will pass just to the east of the Florida east
coast through tonight. The center of Isaias will then move offshore
of the coast of Georgia and southern South Carolina on Monday, move
inland over eastern South Carolina or southern North Carolina Monday
night and move along the coast of the mid-Atlantic states on
Tuesday.
Maximum sustained winds are near 70 mph (110 km/h) with higher
gusts. Some fluctuations in strength are possible during the next
36 hours, but Isaias is expected to be a strong tropical storm when
it reaches the coast of eastern South Carolina or southern North
Carolina Monday night. Slow weakening is forecast after Isaias
makes landfall in the Carolinas and moves across the U.S.
mid-Atlantic region late Monday and Tuesday.
Tropical-storm-force winds extend outward up to 115 miles (185 km)
from the center. A 51 mph (82 km/h) wind gust was recently
measured at NOAA buoy 41009, just off the coast of Cape Canaveral.
NOAA buoy 41010, located about 130 miles (210 km) east-northeast of
Cape Canaveral reported sustained winds of 49 mph (79 km/h) with a
wind gust to 63 mph (101 km/h) within the past couple of hours.
The estimated minimum central pressure is 995 mb (29.39 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 a dangerous 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...
Edisto Beach SC to Cape Fear NC...2-4 ft
Sebastian Inlet FL to Edisto Beach SC...1-3 ft
North of Cape Fear NC to Kiptopeke VA including Pamlico Sound,
Albemarle Sound, Neuse River, Pamlico River, Chesapeake Bay, and
the Tidal Potomac River...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: Hurricane conditions are possible in the watch area in South
and North Carolina Monday night and early Tuesday.
Tropical storm conditions will spread northward within the Tropical
Storm Warning area from Florida to North Carolina through Monday
night.
Tropical storm conditions are possible in the Tropical Storm Watch
area beginning on Tuesday.
RAINFALL: The following rainfall accumulations are expected along
and near the track of Isaias:
Northwest Bahamas: Additional 1 to 3 inches, isolated storm totals
12 inches.
Eastern Florida: Additional 1 to 2 inches, isolated storm totals 4
inches.
Coastal Georgia: 1 to 2 inches.
Carolinas and the mid-Atlantic: 3 to 6 inches, isolated maximum
totals 8 inches.
Southeast New York and much of New England: 2 to 4 inches, isolated
maximum totals 6 inches.
Heavy rainfall from Isaias will continue to result in potentially
life-threatening flash flooding in the Northwest Bahamas through
tonight. Flash and urban flooding, some of which may be significant
in the eastern Carolinas and the mid-Atlantic, is expected through
midweek along and near the path of Isaias across the East Coast of
the United States. Widespread minor to moderate river flooding is
possible across portions of the Carolinas and the mid-Atlantic.
Additionally, quick-responding rivers in the southern Appalachians
and Northeast will be susceptible to minor river flooding.
SURF: Swells generated by Isaias are affecting portions of the
Bahamas and the southeast coast of the United States and will spread
northward along the U.S. east coast during the next couple of days.
These swells are likely to cause life-threatening surf and rip
current conditions. Please consult products from your local weather
office.
TORNADOES: A few tornadoes will be possible over coastal South
Carolina during the afternoon and evening on Monday, and across
eastern North Carolina Monday evening and overnight.
NEXT ADVISORY
-------------
Next intermediate advisory at 200 AM EDT.
Next complete advisory at 500 AM EDT.
$$
Forecaster Pasch
Tropical Storm Isaias Discussion Number 24
NWS National Hurricane Center Miami FL AL092020
1100 PM EDT Sun Aug 02 2020
Isais has not become better organized on satellite and radar imagery
at this time. The cyclone continues to produce vigorous deep
convection but this convection continues to be displaced to the
northeast of the center, and convective banding features are
ill-defined. Air Force Hurricane Hunter observations show that the
central pressure has not fallen since earlier today, and
flight-level and SFMR-observed surface wind measurements from the
aircraft indicate that the intensity remains near 60 kt. Although
Isais will be moving through an environment of fairly strong
southwesterly shear during the next day or so, it will also be
traversing the warm waters of the Gulf Stream with its high oceanic
heat content. The latter factor could result in the system becoming
a hurricane near landfall. The official forecast is close to the
intensity consensus, which keeps Isaias just below hurricane
strength.
It should be emphasized that there is little difference between a
strong tropical storm or a category 1 hurricane, in terms of
impacts.
After landfall, the interaction with land and strong shear should
result in steady weakening. Based on the global models, the
cyclone is likely to become an extratropical cyclone after it moves
into Canada and dissipate over the north Atlantic shortly
thereafter.
The motion continues to be slightly west of due north or 345/8 kt.
There has been no significant change to the track forecast
reasoning. Over the next couple of days, Isaias is expected to
accelerate north-northeastward on the east side of a large 500 mb
trough over the eastern United States and then turn northeastward
in 3 to 4 days as it moves through the mid-latitude westerlies.
The official track forecast is very close to the previous one and
similar to the latest corrected dynamical model consensus. This is
between the GFS, which shows a slightly faster motion and the ECMWF,
which is slightly slower.
Key Messages:
1. There is the danger of life-threatening storm surge inundation of
2 to 4 feet above ground level from Edisto Beach South Carolina to
Cape Fear North Carolina along the immediate coastline and adjacent
waterways. Life-threatening storm surge is possible along the
North Carolina coast from Cape Fear to Duck. Residents in these
areas should follow advice given by local emergency officials.
2. Tropical storm conditions will spread northward within the
Tropical Storm Warning area from Florida to Maryland through
early Tuesday. Isaias is expected to be near hurricane strength when
it reaches the coast of northern South Carolina and southern North
Carolina Monday night, and strong tropical storm force winds are
likely with hurricane conditions possible in the Hurricane Watch
area.
3. Heavy rainfall from Isaias will continue to result in potentially
life-threatening flash flooding in the Northwest Bahamas through
tonight. Flash and urban flooding, some of which may be significant
in the eastern Carolinas and the mid-Atlantic, is expected through
midweek along and near the path of Isaias across the East Coast of
the United States. Widespread minor to moderate river flooding is
possible across portions of the Carolinas and the mid-Atlantic.
4. Tropical storm conditions are forecast to spread northward
across the remainder of the U.S east coast on Tuesday and early
Wednesday. A tropical storm watch is in effect through Long Island
Sound and additional watches and warnings will likely be issued on
Monday.
FORECAST POSITIONS AND MAX WINDS
INIT 03/0300Z 28.5N 79.8W 60 KT 70 MPH
12H 03/1200Z 29.7N 80.0W 60 KT 70 MPH
24H 04/0000Z 32.2N 79.3W 60 KT 70 MPH
36H 04/1200Z 35.9N 77.3W 55 KT 65 MPH...INLAND
48H 05/0000Z 40.5N 74.0W 40 KT 45 MPH...INLAND
60H 05/1200Z 45.5N 70.0W 35 KT 40 MPH...INLAND
72H 06/0000Z 50.0N 65.5W 30 KT 35 MPH...POST-TROP/EXTRATROP
96H 07/0000Z 55.5N 56.5W 25 KT 30 MPH...POST-TROP/EXTRATROP
120H 08/0000Z...DISSIPATED
$$
Forecaster Pasch