Here is the hour by hour breakdown for the storm's arrival on Monday (based on current conditions).
Downtown Savannah:
Mon 11a E 8 mph
12n NE 11
1p N 24 Gusting to 36
2p N 31 G to 44
3p N 30 G to 42
4p N 28 G to 40
5p N 14
6p N 11
7p NW 8
Rainfall total - 1.52" thru Monday 7p
Now here's the same time period Monday for Tybee Island:
Mon 11a NE 38 mph
12n NE 39
1p N 40 Gusting to 51
2p N 40 G to 53
3p N 42 G to 51
4p N 38
5p N 37
6p NW 24
7p NW 18
Rainfall total - 3.27" thru Monday 7p
You can see the predicted times that ISAIAS will have maximum impact for Chatham County. ADD 90 MINUTES for The Lowcountry of South Carolina with a max wind gust near hurricane-force at 68 mph.
Tropical Storm Isaias Intermediate Advisory Number 19A
NWS National Hurricane Center Miami FL AL092020
800 PM EDT Sat Aug 01 2020
...ISAIAS EXPECTED TO RE-STRENGTHEN TO A HURRICANE OVERNIGHT
WHILE IT APPROACHES THE SOUTHEAST COAST OF FLORIDA...
SUMMARY OF 800 PM EDT...0000 UTC...INFORMATION
----------------------------------------------
LOCATION...25.3N 78.9W
ABOUT 100 MI...160 KM SE OF FORT LAUDERDALE FLORIDA
ABOUT 85 MI...135 KM S OF FREEPORT GRAND BAHAMA ISLAND
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H
PRESENT MOVEMENT...NW OR 310 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...993 MB...29.32 INCHES
WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:
The government of the Bahamas has discontinued the Hurricane
Warning for Eleuthera, New Providence, Andros Island, and the
Abacos Islands
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Hurricane Warning is in effect for...
* Boca Raton to the Volusia/Flagler County Line Florida
* Bimini, the Berry Islands, and Grand Bahama Island
A Storm Surge Watch is in effect for...
* Jupiter Inlet to Ponte Vedra Beach Florida
A Tropical Storm Warning is in effect for...
* North of Ocean Reef to south of Boca Raton Florida
* Lake Okeechobee
* Volusia/Flagler County Line to Ponte Vedra Beach Florida
A Tropical Storm Watch is in effect for...
* North of Ponte Vedra Beach Florida to South Santee River South
Carolina
Interests elsewhere along the southeast and mid-Atlantic coasts of
the United States should monitor the progress of Isaias. Additional
watches or warnings may be required tonight or Sunday.
A Hurricane Warning means that hurricane conditions are expected
somewhere within the warning area. Preparations to protect life
and property should be rushed to completion.
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.
For a depiction of areas at risk, please see the National Weather
Service Storm Surge Watch/Warning Graphic, available at
hurricanes.gov.
A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area.
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 800 PM EDT (0000 UTC), the center of Tropical Storm Isaias was
located by an Air Force Hurricane Hunter aircraft near latitude 25.3
North, longitude 78.9 West. Isaias is moving toward the northwest
near 9 mph (15 km/h). A general northwestward motion with some
decrease in forward speed is expected for the next day or so,
followed by a north-northwestward motion by late Sunday. A turn
toward the north and north-northeast is anticipated on Monday and
Tuesday with an increase in forward speed. On the forecast track,
the center of Isaias will approach the southeast coast of Florida
tonight and move near or along the east coast of Florida Sunday and
Sunday night. On Monday and Tuesday, the center of Isaias will move
from offshore of the coast of Georgia into the southern mid-Atlantic
states.
Maximum sustained winds are near 70 mph (110 km/h) with higher
gusts. Some restrengthening is forecast, and Isaias is expected to
regain hurricane strength later tonight and early Sunday. Slow
weakening is expected to begin Sunday night and continue through
Monday.
Tropical-storm-force winds extend outward up to 105 miles (165 km)
from the center. Settlement Point, Grand Bahama Island, recently
reported a wind gust of 41 mph (66 km/h). An unofficial observing
station in Ft. Lauderdale Beach recently reported a wind gust of 39
mph (63 km/h).
The estimated minimum central pressure based on Hurricane Hunter
aircraft data is 993 mb (29.32 inches).