Flooding downpours, severe thunderstorms to mitigate heat in East
Heavy rain from Chantal, followed by slow-moving fronts, will bring the risk of torrential rainfall and flash flooding to parts of the eastern U.S. this week.
This aerial video shows widespread flooding overtaking parks, roads, homes and businesses in Durham, North Carolina, on July 7. Several motorists were also seen stranded in the floodwaters.
Even after flooding downpours associated with Chantal, now a tropical rainstorm, exit the Atlantic coast, additional ripples in the atmosphere will produce more pop-up showers and severe thunderstorms in the East, which will tend to regulate the heat but continue the flash flood risk.
AccuWeather declared the cluster of showers and thunderstorms northeast of Florida a tropical rainstorm last week, ahead of the official designation of a tropical depression or storm. The National Hurricane Center later dubbed the area a tropical depression on Friday. Then, as the depression strengthened, on Saturday, Tropical Storm Chantal was named. Since then, Chantal moved inland over the Carolinas with heavy rain, localized flooding and gusty winds.
Chantal dumped a general 5-10 inches of rain on parts of the Carolinas and triggered dangerous flash flooding.
There's an old saying among AccuWeather tenured meteorologists that "tropical cyclones are slow to die even though they may lose wind intensity."
Thus, Chantal remains a concern.
"Even though Chantal continues to lose wind intensity, storms of this nature can play tricks and suddenly spring back to life in the form of torrential rainfall and severe thunderstorms," AccuWeather Chief Meteorologist Jonathan Porter said.
"We are concerned that since Chantal is still close to warm water and moisture sources that it can trigger rainfall heavy enough to continue to cause flash flooding from eastern Virginia to the Delmarva Peninsula and part of southern New Jersey into Monday evening and perhaps even parts of central and eastern Long Island, New York, during Monday night," Porter added.
This is why AccuWeather meteorologists will continue to refer to Chantal as a tropical rainstorm, long after it loses depression status and until the storm is no longer a threat to land.
A general 1-4 inches of rain is forecast from eastern Virginia through southern New Jersey and parts of Long Island, with locally higher amounts.
Much of that rain may fall in two to three hours, which is more than enough to overwhelm storm drains and small streams.
Adding to Chantal's moisture will be the day's heating and an unstable atmosphere.
Thunderstorms will tend to erupt well to the north and west, especially along a slowly advancing frontal zone from the Midwest and the eastern Great Lakes. Some of the storms may also pack highly localized damaging wind gusts or downburst winds.
After Chantal moves out to sea on Tuesday, daytime heating and fronts moving into the region will continue to set off periodic showers, thunderstorms and localized severe weather from parts of New England to the southern Appalachians and the southern Atlantic Seaboard through the week.
The main threat from the ongoing, nearly daily rounds of thunderstorms in some areas will be flash flooding, especially where it rained hard the day before, saturated the ground and pushed small stream levels up.
The downpours will tend to mitigate the heat, as some of the sun's energy will be used to dry out the ground and set off the storms. Should an area of high pressure nearby be stronger, there would be less thunderstorm activity and much higher temperatures over a broad area this week.
Correspondingly, where downpours miss a particular region daily, temperatures can climb to every degree possible with highs well into the 90s F. This is most likely over portions of the interior Carolinas and Georgia.
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