Severe weather is possible in portions of the Mid Atlantic for Monday, Memorial Day. The National Weather Service’s Storm Prediction Center (SPC) is highlighting the elevated risk for severe weather today in their Convective Outlook. According to the SPC, severe thunderstorms are forecast to develop Monday afternoon and overspread much of the Mid Atlantic accompanied by a risk for damaging wind
gusts into Monday evening. An isolated tornado or two cannot be ruled out.
According to the SPC, models indicate that mid/upper flow will undergo amplification across the northern mid-latitudes of the Pacific into North America into and through Monday into Monday night. Farther downstream, it appears that larger-scale troughing will continue to evolve east of the upper Mississippi Valley into the northern and middle Atlantic Seaboard. One significant embedded short wave may pivot north-northeast of Lake Huron and Georgian Bay, accompanied by a relatively compact, but deep surface cyclone. A trailing perturbation is forecast to pivot eastward and northeastward through the Ohio Valley and lower Great Lakes region, with increasingly difluent and divergent upper flow likely overspreading the Mid Atlantic region during the late afternoon and evening. While surface troughing deepens to the lee of the Blue Ridge during the day in response to this forcing, a cold front trailing the cyclone likely will advance toward the Appalachians, as well as into the Gulf States, before progressing into the Atlantic Seaboard Monday night.
Based on this meteorological set-up, strong to severe thunderstorms are forecast to blossom on Monday in the Mid Atlantic. The greatest threat of severe weather for Memorial Day (and night) is over most of Virginia and Maryland, all of Delaware, northern and central portions of North Carolina, south and eastern Pennsylvania, and south and western New Jersey. The cities of Philadelphia, Atlantic City, Dover, Baltimore, Roanoke, and Washington DC are included in this hazard area.
According to the SPC, strengthening deep-layer shear and mean wind fields will contribute to an environment potentially conducive to organized severe thunderstorm development within this heightened risk area. This could include a risk for supercells, at least initially, but
pre-frontal convection developing along or across the Appalachians may evolve into an increasingly organized line while spreading east of the Blue Ridge late Monday afternoon and evening. As this occurs, severe wind gusts will probably become the primary potential hazard after initial, more discrete storms pose a risk for severe hail, locally damaging wind gusts, and perhaps a risk for a tornado or two.
The National Weather Service will continue to monitor this developing severe weather region over the holiday weekend and could issue Tornado or Severe Thunderstorm Watches on Monday ahead of the storm’s arrival. When storms actually form and begin to impact communities in the Mid Atlantic, the National Weather Service may upgrade watches to warnings as conditions warrant.
