1. There is the danger of life-threatening storm surge inundation along portions of the immediate coastline and adjacent waterways of northeastern South Carolina and the North Carolina coast in the Storm Surge Warning area. Residents in these areas should follow advice given by local emergency officials.

2. Isaias is forecast to regain hurricane strength before it reaches the coast of northeastern South Carolina and southern North Carolina, and hurricane conditions are expected in the Hurricane Warning area by this evening. Preparations should be rushed to completion.

3. Isaias is expected to bring widespread sustained tropical storm force winds and wind gusts to hurricane force to the mid-Atlantic coast Tuesday, which could cause tree damage and power outages. Tropical storm conditions are expected to reach southern New England on late Tuesday and are possible along the northern New England coast Tuesday night and early Wednesday.

4. Heavy rainfall will result in flash and urban flooding, some of which may be significant in the eastern Carolinas and the mid-Atlantic, through Tuesday night near the path of Isaias up the East Coast of the United States. Widespread minor to moderate river flooding is possible across portions of the Carolinas and the Mid-Atlantic.

CHANGES WITH THIS ADVISORY:

A Storm Surge Warning has been issued for portions of the Pamlico and Albemarle Sounds, including the Neuse and Pamlico Rivers, and for the North Carolina Outer Banks form Oregon Inlet to the North Carolina/Virginia border.

The Tropical Storm Warning has been extended northward to the mouth of the Merrimack River, including Martha's Vineyard, Nantucket, and Block Island.

The Tropical Storm Watch for the remainder of the Chesapeake Bay and the Tidal Potomac River north of Cobb Island has been changed to a Tropical Storm Warning.

The Tropical Storm Watch has been extended northward to Eastport Maine.

The Tropical Storm Warning has been discontinued south of Altamaha Sound.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Storm Surge Warning is in effect for...
- Edisto Beach South Carolina to Cape Fear North Carolina
- Pamlico and Albemarle Sounds, including the Neuse and Pamlico Rivers
- Oregon Inlet North Carolina to the North Carolina/Virginia border

A Storm Surge Watch is in effect for...
- Cape Fear to Oregon Inlet North Carolina

A Hurricane Warning is in effect for...
- South Santee River South Carolina to Surf City North Carolina

A Tropical Storm Warning is in effect for...
- Altamaha Sound Georgia to South Santee River South Carolina
- North of Surf City North Carolina to the Mouth of the Merrimack River
- Pamlico and Albemarle Sounds
- Chesapeake Bay
- Tidal Potomac River
- Delaware Bay
- Long Island and Long Island Sound
- Martha's Vineyard, Nantucket, and Block Island

A Tropical Storm Watch is in effect for...
- Mouth of the Merrimack River to Eastport Maine

Interests elsewhere along the northeast coast of the United States should monitor the progress of Isaias. Additional watches or warnings may be required later today.

A Storm Surge Warning means there is a danger of lifethreatening 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 lifethreatening 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 Warning means that hurricane conditions are expected somewhere within the warning area, in this case within 24 hours. Preparations to protect life and property should be rushed to completion.

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, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office.

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...

South Santee River SC to Cape Fear NC...35 ft Edisto Beach SC to South Santee River SC...24 ft Cape Fear NC to the North Carolina/Virginia border including Pamlico Sound, Albemarle Sound, Neuse and Pamlico Rivers...24 ft Altamaha Sound GA to Edisto Beach SC...13 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 Sound13 ft The deepest water will occur along the immediate coast in areas of onshore winds, where the surge will be accompanied by large waves. Surgerelated 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 expected within the hurricane warning area in South and North Carolina this evening through tonight, with tropical storm conditions beginning later today.

Widespread tropicalstormconditions are expected in the tropical storm warning area from coastal North Carolina to the midAtlantic states tonight and Tuesday, with wind gusts to hurricane force possible. These winds could cause tree damage and power outages.

Tropical storm conditions are expected to reach southern New England late Tuesday and are possible along the northern New England coast Tuesday night and early Wednesday.

RAINFALL: The following rainfall accumulations are expected along and near the track of Isaias:

Carolinas and the MidAtlantic: 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 result in flash and urban flooding, some of which may be significant in the eastern Carolinas and the midAtlantic, through Tuesday night near the path of Isaias up the East Coast of the United States. Widespread minor to moderate river flooding is possible across portions of the Carolinas and the midAtlantic. Additionally, quickresponding 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 lifethreatening surf and rip current conditions. Please consult products from your local weather office.

TORNADOES: A few tornadoes will be possible over coastal South Carolina beginning this evening, spreading across eastern North Carolina tonight into Tuesday morning. A couple tornadoes will be possible on Tuesday from eastern Virginia northeastward into southern New England.

At 200 PM EDT (1800 UTC), the center of Tropical Storm Isaias was located by an Air Force Reserve reconnaissance aircraft and NOAA Doppler weather radars near latitude 31.2 North, longitude 80.0 West. Isaias is moving toward the north near 13 mph (20 km/h), and this general motion is expected to continue this afternoon. A turn toward the northnortheast along with a slight increase in forward speed is expected by early this evening, followed by a faster motion tonight and Tuesday. On the forecast track, the center of Isaias will pass well east of the Georgia coast through this afternoon. The center of Isaias will then approach the coasts of northeastern South Carolina and southern North Carolina within the hurricane warning area this evening. The center will then move inland over eastern North Carolina tonight, and move along the coast of the midAtlantic states on Tuesday and into the northeastern United States Tuesday night.

Data from the reconnaissance aircraft and NOAA Doppler weather radars indicate that maximum sustained winds remain near 70 mph (110 km/h) with higher gusts. Some strengthening is forecast this afternoon or early evening, and Isaias is expected to regain hurricane strength just before the cyclone reaches the coast of northeastern South Carolina or southern North Carolina tonight. Only slow weakening is anticipated after Isaias makes landfall in the Carolinas and moves across the U.S. midAtlantic region tonight and Tuesday.

Tropicalstormforce winds extend outward up to 125 miles (205 km) from the center. During the past hour, a wind gust to 40 mph (65 km/h) occurred at Folly Island Pier, South Carolina, and at COMRP buoy 41033 located just offshore Fripp Island, South Carolina.

The estimated minimum central pressure based on recent reports from the aircraft is 993 mb (29.32 inches).

Isaias continues to undergo strong bursting and then weakening convective phases, with the cyclone currently in the latter mode. Satellite and radar data indicate that Isaias' convective organization has become a little disheveled since the previous advisory, but this is to be expected since the tropical cyclone has been undergoing bursting periods about every 8 hours or so beginning overnight around 0600-0900Z. Thus, the system is due for another re-organization phase shortly if it holds true to form. That may already be underway based on recent radar and recon data showing a slight eastward shift in the center position. The highest 700-mb flight-level wind observed has been 63 kt, which reduces to about a 57-kt surface wind. Jacksonville Doppler radar velocities north and north-northwest of the center have been around 60 kt at 9,000 ft, which equals about 54 kt surface winds. The initial intensity will be held at 60 kt, perhaps a little generously, for this advisory despite the recent rise in the central pressure to around 998 mb.Isaias is still moving northward but a little faster at 360/11 kt. The track forecast reasoning remains essentially the same as the previous few advisories, with Isaias expected to gradually turn toward the north-northeast later today and begin to accelerate by this evening. The latest NHC model guidance is more tightly packed about the previous advisory track, so only minor tweaks were required. The new NHC track forecast lies very close to a blend of the multi-model consensus aids TVCA, GFEX, TVCX, and NOAA-HCCA.Current westerly vertical wind shear of 20-25 kt is expected to decrease somewhat during the next 12 h and also become more southwesterly, which will be in better alignment with Isaias' forward motion vector. The decrease in the shear should result in less tilt to the cyclone, allowing Isaias to strengthen and regain hurricane status just before making landfall, and most of the intensity guidance shows a 60-65 kt system at that time. After landfall, Isaias is forecast to only slowly weaken due to interaction with an unusually strong winter-type jetstream that will be possessing winds of 100-120 kt. Expected strong baroclinic forcing will keep Isaias' circulation intact and also produce very strong wind gusts along the Mid-Atlantic states tomorrow. As a result, the gust factors at 24-48 h have been increased above the standard 20 percent in the Forecast/Advisory (TCMAT4). The cyclone is forecast to be absorbed by a larger extratropical low over Canada in 3-4 days.