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WHAT TO KNOW: Flooding rain threat increasing as Isaias nears Virginia

Here's what you need to know about the impacts to Southwest and Central VA.
Slow-moving storms will bring heavy rain to the region from Isaias Monday into Tuesday. Impacts depend on locations closest to the storm.
Slow-moving storms will bring heavy rain to the region from Isaias Monday into Tuesday. Impacts depend on locations closest to the storm.(WDBJ)
Published: Aug. 2, 2020 at 1:13 PM EDT|Updated: Aug. 2, 2020 at 4:29 PM EDT
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Flash Flood Watches have already been issued for parts of the area (View Alerts) as Tropical Storm Isaias’ inches closer to our region. We’re already seeing some stronger storms and pockets of heavy rain this morning. We’ll continue with that trend for the rest of today and tomorrow which may lead to runoff and localized flooding. Remain weather area and have a way of getting alerts.

As Isaias inches closer we'll continue to see pockets of heavy rainfall.
As Isaias inches closer we'll continue to see pockets of heavy rainfall.(WDBJ)

FLASH FLOOD WATCH

A FLASH FLOOD WATCH has been issued by the National Weather Service for areas along and east of the Blue Ridge Parkway from early Monday through Tuesday evening. Flash flood watches go into effect at 8 AM for Carroll, Floyd, Grayson and Patrick counties and 2 PM for the rest. Excessive rainfall may be enhanced by the remnants of Tropical Storm Isaias combined with an approaching front. While we aren’t expecting widespread flooding issues, small creeks and streams could rise and flood quickly starting today and again Tuesday. We’ll need to keep an eye on area rivers as well starting Tuesday. Rainfall of 2-4″ is likely with some hometowns getting more than 4″, especially in the eastern part of our region.

Excessive rainfall may lead to localized flooding across the watch area.
Excessive rainfall may lead to localized flooding across the watch area.(WDBJ)

THE TRACK

Very few changes in the track have occurred in recent days with the center of the storm expected to track along the coast or slightly inland Monday and Tuesday. Keep in mind, impacts from tropical systems often fall well outside the visual “cone of uncertainty” which is used to depict the possible path of the storm’s center. We will certainly get rain, but areas along and east of the Blue Ridge, especially areas such as South Boston, Danville, and even Lynchburg, have a higher risk of significant rainfall that may cause flooding.

HEAVY RAIN & FLOODING

There will likely be an ideal set-up for what is called a Predecessor Rainfall Event (PRE) which happens when tropical moisture moves into our area well ahead of the tropical storm itself and triggers rainfall. This began Sunday and will continue through Tuesday as the tropical system nears. A cold front will also approach the area helping to squeeze out rainfall adding to the flood risk.

WIDESPREAD RAINFALL: 2″ to 4″ inches (with locally higher amounts) can be expected along and east of the Blue Ridge Parkway (Roanoke, Smith Mountain Lake, Floyd, Rocky Mount and the NRV and Highlands).

LOCALLY HEAVY RAINFALL: 3″ to 5″+ is likely closest to the tropical storm for areas across the Southside into Central Virginia (Danville, South Boston, Lynchburg, Appomattox).

The EUROPEAN model has been featuring some of the highest projected totals with this event. While these may seem a bit extreme, it gives us an indication that some intense rain is possible, especially east, with lesser totals to the west Monday and Tuesday.

The Euro continues to show the highest projected rain totals (3-5"+) across the eastern third of our region.
The Euro continues to show the highest projected rain totals (3-5"+) across the eastern third of our region.(WDBJ)

The highest rain and storm probabilities will be from late Monday through late Tuesday, decreasing rapidly Wednesday as the system exits to our northeast. The tropical air and humid conditions will linger into the week as we shift to a more isolated to scattered storm scenario through the rest of the week.

WIND IMPACTS

With the center of the storm closer to the coast, wind impacts shouldn’t be as high for our region. However, areas such as Lynchburg and Southside may experience gusts over 20mph late Tuesday as the storm is closest to our area.

Our higher mountain ridgetops (Blue Ridge Parkway, Catawba, Highlands) may also observe gusts over 20mph at times. While these aren’t exceptionally strong, with the soggy ground, a few trees may come down.

Any stronger winds will likely remain closer to the storm in our eastern counties Tuesday.
Any stronger winds will likely remain closer to the storm in our eastern counties Tuesday.(WDBJ)

TORNADO IMPACT

While tornadoes with tropical systems are common, our area will be on the western side, not typically known for increased tornadoes. At this point, our tornado risk appears low. That could always change with any shift in track or strong thunderstorms that develop.

WHAT TO DO?

We see systems like this every few years and it’s often easy to get caught up in the push of urgent information. The main things to do is:

  1. Follow the weather closely and have a way to get flood and severe weather warnings. Download the WDBJ7 Weather app and be sure Flood and Severe notifications are turned ON.
  2. If you live along streams and rivers, have an evacuation plan ready to go should water get high during the event. Get stream information here.
  3. Driving in the heavy rain is one thing, but you NEVER want to cross flooded roads! Have alternate routes planned should your normal route get flooded.

Stay with WDBJ7 for the latest on Isaias and the local impacts.

Copyright 2020 WDBJ. All rights reserved.

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