Impressive severe thunderstorm threat I am very impressed with the severe thunderstorm threat around here for later today and early tonight. The atmosphere is extremely unstable and while the radar is currently not all that active at this time, it is likely to explode with activity in the next few hours. There are several stability indices that are pointing to the region between DC and NW NJ as prime areas of instability. One such measurement of the stability of the troposphere is called the surface-based “Convective Available Potential Energy (CAPE)” and it has very high values of up to 4000 J/KG showing up right now across DC, eastern PA, and western New Jersey. Lines of thunderstorms are likely to form over the next couple of hours from north-central PA to eastern West Virginia then roll eastward. Any storm that reaches the I-95 corridor later today and tonight can produce damaging wind gusts, torrential downpours and hail. The National Weather Service currently does not have a severe thunderstorm watch up for the I-95 corridor region, but that could (and should) happen later today. The threat continues on Thursday and Thursday night for more heavy rainfall and strong thunderstorms in the I-95 corridor.
Tropical Storm Arthur Arthur is now a strong tropical storm with sustained winds at 60 mph. It is moving slowly to the north at 7 mph and will intensify rapidly tonight and Thursday. The current pressure is down to 29.44 inches and that should drop rather sharply over the next 24 hours. Arthur could very well reach hurricane status – perhaps even category 2 - before directly impacting the Outer Banks of North Carolina late Thursday into early Friday. After Arthur reaches northeastern North Carolina, it will take a turn to the northeast and ride a couple of hundred miles off the Mid-Atlantic coastline later Friday. Showers could linger around here into the morning hours on Friday, but drier air should return by Friday night - Saturday and Sunday look like great weather days in the Mid-Atlantic region.