Tropical Storm Debby Meanders Through The SE US

101 

WTNT34 KNHC 070233

TCPAT4

BULLETIN

Tropical Storm Debby Advisory Number  19

NWS National Hurricane Center Miami FL       AL042024

1100 PM EDT Tue Aug 06 2024

...DEBBY MOVING SLOWLY EASTWARD OFFSHORE OF THE COASTS OF GEORGIA

AND SOUTH CAROLINA...

...MAJOR FLOOD THREAT FOR PORTIONS OF THE SOUTHEASTERN UNITED

STATES THIS WEEK...

SUMMARY OF 1100 PM EDT...0300 UTC...INFORMATION

-----------------------------------------------

LOCATION...31.8N 80.2W

ABOUT 50 MI...80 KM ESE OF SAVANNAH GEORGIA

ABOUT 70 MI...115 KM SSW OF CHARLESTON SOUTH CAROLINA

MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H

PRESENT MOVEMENT...E OR 90 DEGREES AT 5 MPH...7 KM/H

MINIMUM CENTRAL PRESSURE...996 MB...29.42 INCHES

WATCHES AND WARNINGS

--------------------

CHANGES WITH THIS ADVISORY:

The Tropical Storm Warning has been discontinued for the coast of

Georgia from the mouth of the Savannah River southward.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Storm Surge Watch is in effect for...

* North of South Santee River, South Carolina to Cape Fear, North

Carolina

A Tropical Storm Warning is in effect for...

* North of the mouth of thee Savannah River to Surf City, North

Carolina

A Tropical Storm Watch is in effect for...

* North of Surf City, North Carolina to Beaufort Inlet, North

Carolina

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.

Interests elsewhere along the southeastern coast of the United

States should monitor the progress of this system. Additional

watches or warnings may be required on Wednesday.

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 PM EDT (0300 UTC), the center of Tropical Storm Debby was

located near latitude 31.8 North, longitude 80.2 West. Debby is

moving toward the east near 5 mph (7 km/h).  A slow motion toward 

the east and then north is expected through Thursday night. On the 

forecast track, the center of Debby is expected to slowly move away 

from the coast of Georgia and South Carolina tonight, continue to 

drift offshore through early Thursday, and then move inland over 

South Carolina on Thursday.

Maximum sustained winds are near 40 mph (65 km/h) with higher gusts.

Some strengthening is forecast while the center of Debby remains 

offshore. Weakening is expected Thursday night and Friday after 

landfall.

Tropical-storm-force winds extend outward up to 205 miles (335 km)

from the center.

The estimated minimum central pressure based on surface 

observations is 996 mb (29.42 inches).

HAZARDS AFFECTING LAND

----------------------

Key messages for Debby can be found in the Tropical Cyclone

Discussion under AWIPS header MIATCDAT4 and WMO header WTNT44 KNHC.

WIND: Tropical storm conditions are expected to continue along the

coast of South Carolina within the tropical storm warning area

through Thursday night.  Tropical storm conditions are expected

within the tropical storm warning area in North Carolina beginning

early Wednesday.  Tropical Storm conditions are possible within the

Tropical Storm Watch area in North Carolina beginning Wednesday.

STORM SURGE: The combination of storm surge and 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...

South Santee River, SC to Cape Fear, NC...2-4 ft

For a complete depiction of areas at risk of storm surge inundation,

please see the National Weather Service Peak Storm Surge Graphic,

available at hurricanes.gov/graphics_at4.shtml?peakSurge.

RAINFALL: Debby is expected to produce potentially historic storm

total rainfall of 10 to 20 inches, with maximum amounts of 25

inches, bringing areas of catastrophic flooding across portions of

eastern South Carolina and southeast North Carolina through Friday.

From central South Carolina to the Upstate of South Carolina,

northward into Southwest Virginia,  portions of the Mid-Atlantic

States, western and northern New York State into Northern New

England, 3 to 6 inches with local amounts to 8 inches, are expected

through Saturday. This rainfall will likely result in areas of

considerable flash and urban flooding, with river flooding possible.

An additional scattered 1 to 3 inches of rainfall is possible across

southeast Georgia through tonight, which may aggravate any ongoing 

flooding conditions across that vicinity.

For a complete depiction of forecast rainfall and flash flooding

associated with  Debby, please see the National Weather Service

Storm Total Rainfall Graphic, available at

hurricanes.gov/graphics_at4.shtml?rainqpf and the Flash Flood Risk

graphic at hurricanes.gov/graphics_at4.shtml?ero.  For a list of

rainfall observations (and wind reports) associated this storm, see

the companion storm summary at WBCSCCNS4 with the WMO header ACUS44

KWBC or at the following link:

www.wpc.ncep.noaa.gov/discussions/nfdscc4.html.

TORNADOES: A few tornadoes are possible over portions of coastal

South Carolina and North Carolina through Wednesday morning.

SURF:  Large swells will continue to affect the Southeast U.S.

coast through the end of the week. These conditions are likely to

cause life-threatening surf and rip current conditions. Please

consult products from your local weather office.

NEXT ADVISORY

-------------

Next intermediate advisory at 200 AM EDT.

Next complete advisory at 500 AM EDT.

$$

Forecaster Beven

ZCZC MIATCDAT4 ALL

TTAA00 KNHC DDHHMM

Tropical Storm Debby Discussion Number  19

NWS National Hurricane Center Miami FL       AL042024

1100 PM EDT Tue Aug 06 2024

Surface, satellite, and radar observations indicate that the

center of Debby has emerged over the Atlantic southeast of

Savannah, Georgia.  The system is currently comprised of a large

swirl of shallow to moderate convection with occasional patches of

deep convection, particularly in bands to the east of the center.

GOES-16 airmass imagery indicates that interaction with an

upper-level trough has spread cool/dry air aloft over the low-level

center, making the cyclone look somewhat subtropical.  The initial

intensity is held at 35 kt based on Doppler radar winds in the

bands east of the center and a recent 1-minute wind of 31 kt at

NOAA buoy 41008 to the southwest of the center.

Debby is moving slowly and somewhat erratically eastward, with the

initial motion of 090/4.  The track guidance continues to show a

generally eastward motion for the next 12-18 h, taking the center a

little farther away from the coast.  After that, a building

mid-level ridge should cause the system to turn northward and move

back inland between 24-36 h.  Subsequently, Debby is likely to

accelerate northward and northeastward over the eastern and

northeastern U.S. on the east side of an approaching

mid-latitude trough.  The new forecast track has been adjusted a

little to the left of the previous track through 48 h to better

match the consensus models, and it has been adjusted to the right

during the extratropical phase to better match the global model

guidance.

The dry air aloft, the lack of an inner wind core, and the lack of

deep convection suggest that Debby is at best going to strengthen

slowly, and this scenario is supported by the majority of the

intensity forecast guidance.  The new intensity forecast calls for

gradual strengthening until the cyclone makes landfall between the 

24 and 36 h forecast points.  Weakening is expected after landfall, 

with Debby expected to become post-tropical around 72 h and 

complete transition to an extratropical cyclone by 96 h. The new 

intensity forecast is at the high end of the intensity guidance 

through 36 h and near the intensity consensus after that.

Key Messages:

1. Potentially historic heavy rainfall across portions of eastern 

South Carolina through Friday will likely result in areas of 

catastrophic flooding. Heavy rainfall will likely result in 

considerable flooding impacts from central to the Upstate of South 

Carolina, western North Carolina, Southwest Virginia through 

portions of Mid-Atlantic States, western and northern New York State 

and northern New England through Saturday. 

2. Tropical storm conditions will spread northward along the

southeast U.S. coast from South Carolina to North Carolina through 

Thursday.  Tropical storm warnings and watches are in effect

for portions of that area.

3. A dangerous storm surge is possible along the coast of South

Carolina and southeastern North Carolina from South Santee River to

Cape Fear.  Residents in that area should follow any advice given by

local officials.

FORECAST POSITIONS AND MAX WINDS

INIT  07/0300Z 31.8N  80.2W   35 KT  40 MPH

 12H  07/1200Z 32.0N  79.6W   40 KT  45 MPH

 24H  08/0000Z 32.6N  79.5W   45 KT  50 MPH

 36H  08/1200Z 33.4N  79.7W   45 KT  50 MPH...INLAND

 48H  09/0000Z 34.7N  79.9W   35 KT  40 MPH...INLAND

 60H  09/1200Z 36.9N  79.4W   30 KT  35 MPH...INLAND

 72H  10/0000Z 39.9N  77.2W   30 KT  35 MPH...POST-TROP/REMNT LOW

 96H  11/0000Z 47.1N  69.5W   30 KT  35 MPH...POST-TROP/EXTRATROP

120H  12/0000Z 51.5N  61.0W   30 KT  35 MPH...POST-TROP/EXTRATROP

$$

Forecaster Beven

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