Multiple days of severe weather continues from the Southern Plains through portions of the Northeast this Monday and even into Tuesday. Some of these storms will become entrained by tropical moisture, allowing for heavy downpours to occur. Now on Monday, the severe weather threat will be more widespread, threatening over 70 million people in the country. This threat spans from West Texas through portions of the Ohio Valley and Great Lakes region and into the Mid-Atlantic. Hail and damaging winds will be the risks with these storms while there is a small tornado risk in eastern Colorado and parts of the Central Plains, eastern Florida, and the central Appalachians.
This morning, there is a line of strong storms working southeastward from the Chicagoland area. This line may evolve into a derecho as the line “bows out” into an intense line of damaging winds, tracking from southwestern Pennsylvania through the southern Mid-Atlantic region, including Washington, DC and Baltimore, through this evening. Therefore, widespread wind damage can be expected. The Storm Prediction Center has indicated that the risk for damaging storms is increasing, and they may have to elevate the threat even further to a ‘Moderate Risk.’ A ‘Moderate Risk’ is the second highest category in their thunderstorm outlook.
Update from @NWSSPC on the increasing #severe weather risk in the Mid-Atlantic: “potential exists for a #derecho with widespread damaging winds… an upgrade to Moderate risk may occur if even greater damaging wind coverage becomes evident with the 20Z (4pm) outlook.” pic.twitter.com/HdFODoZYfk
— WeatherOptics (@weatheroptics) May 14, 2018
Back to the west, scattered showers and storms will be around in the Central Plains during the morning hours. Those storms will intensify by the evening as they track into Missouri. Scattered storms will also develop from central Kansas down through West Texas by the end of the day, and these storms will likely be severe. Then overnight, those storms will congeal into a line of severe storms while slowly moving east and weakening once they get toward the ArkLaTex. That line over Missouri will also weaken once they reach the western Ohio River Valley. Otherwise Monday night, there will be scattered showers and storms found around much of the Midwest and Great Lakes regions.
Then on Tuesday, the severe weather risk will be focused over the northern Mid-Atlantic and central and southern New England. The environment will be conducive for severe storms and even an isolated tornado in this area. In the NAM model image below, it outlines where the best instability, or CAPE, in the atmosphere will be located in the evening. It also shows using the wind barbs the strength of the winds at different heights and their directions. Notice the significant change in wind by height over eastern Pennsylvania, all of New Jersey, and into the Tri-State Area of New York City. This in indicates where the worst of the storms may be as well as the greatest risk for a tornado or two.
In terms of timing, this will be a late-day event. In the morning, there will be showers and storms across the Great Lakes region and northern New England. There will also be leftover storms in the Red River Valley of the Southern Plains. Farther west of there is also the risk for severe weather in northwestern Texas and southwestern Oklahoma. Then into the afternoon, a strong line of thunderstorms will begin to develop after emerging from Lake Erie and the Canadian border in western New York. This line will work southeastward toward the I-95 corridor by the evening, affecting all of New England and much of the Mid-Atlantic. Storms are expected to move into cities like Boston, New York, and Philadelphia between 7 and 10pm. Down toward Washington, D.C., a new line of storms may develop on the southern extend of this first line, orientating from west to east. This line of scattered showers and storms will impact portions of the Ohio Valley and Mid-Atlantic Tuesday night. Back into the Southern Plains, a line of severe storms will quickly develop in West Texas a few hours before sundown. This line will move east before weakening overnight once they reach central Oklahoma City and Dallas-Fort Worth.
A new storm moving in midweek will begin the risk for additional severe weather for the latter half of this week. The risk for storms will be low, but will threaten most of the western Plains on Wednesday.