Ida was downgraded to a Tropical Storm this morning. Maximum sustained winds are now at 60 mph and Ida is expected to become a Tropical Depression by this evening. Unfortunately, the “worst-case scenario” played out across Metropolitan New Orleans, as Ida made landfall early Sunday afternoon across Southeast Louisiana with maximum sustained winds of 150 mph. Over one million customers are without power across Southeast Louisiana.
Ida will move northeast into the Tennesse River Valley and Southern Appalachians over the next few days. A cold front is expected to move from the Great Lakes Region south and east into the Ohio River Valley. There remain questions in regards to how far south and east the cold front will move until stalling. This will determine where the heaviest rain sets up and will help steer Ida toward the northeast.
The ENTIRE Mid-Atlantic and DMV Region will need to monitor the potential for severe thunderstorms capable of producing isolated tornadoes Tuesday afternoon. Since Ida will still have some tropical characteristics as it moves into the Tennesse River Valley and Mid-Atlantic Region, there is the threat of tornadoes, mainly to the east of the center. By Tuesday evening, moisture from Ida will begin to move across the Mid-Atlantic. With the center of Ida across Central and Eastern Tennessee, there will likely be enough instability and wind sheer present for some of these thunderstorms to produce a few isolated tornadoes. Any sunshine Tuesday afternoon will help to increase the risk for severe weather.
By Wednesday morning, model guidance is in agreement that the center of Ida will be across Far Southwest Virginia. Ida will begin to merge with the stationary front and the tornado threat should begin to lower by late Wednesday. Then, we move from a tornado risk to very heavy rain and flash flooding risk. Ida and a front combined will help to act as a “sponge” and wring every bit of moisture available in the atmosphere. With a very humid airmass already in place, this sets the stage for rainfall amounts 1 to 2 inches per hour across the valleys and ridges of Virginia and West Virginia.
There is a high probability Wednesday into early Thursday for very heavy rain and flooding across much of the DMV Region. Rainfall rates of 1 to 2 inches per hour will likely cause creeks, streams, and rivers to rise and potentially overflow onto highways. Across Central and portions of Southern and Southwestern Virginia, there is an enhanced probability for very heavy rainfall to cause areas of flash flooding.
Rainfall amounts will range 2 to 4 inches across much of the DMV Region with locally higher amounts greater than 5 inches, mainly across portions of the Blue Ridge. Across the rest of the Mid-Atlantic Region, 1 to locally 2 inches of rain is likely across the Metro Richmond area, Hampton Roads, and Lower Eastern Shore.
We will continue to monitor any changes in the forecast and keep you updated with the very latest.