Intense storms expected in the area south of the DC metro area Friday afternoon


2 p.m. – Severe thunderstorm watch posted for north-central Virginia and southern Maryland

The National Weather Service has issued a severe thunderstorm watch for areas south of the immediate DC metropolitan area because that’s where fuel for severe thunderstorms is most prevalent. To the north, cloud cover slowed the rise of instability.

A line of severe storms has developed along the Interstate 95 corridor between Fredericksburg and Richmond and will sweep east across the northern neck of Virginia and the southern portion of southern Maryland over the next two hours. .

In the immediate area we are still expecting showers and scattered thunderstorms later this afternoon into the evening. The activity that is currently developing near and west of Interstate 81 is pushing east. We cannot rule out isolated severe weather events and will monitor the situation.

Original article from 1:30 p.m.

As a cold front approaches the DC area this afternoon, it will encounter warm heavy air, triggering scattered showers and thunderstorms in parts of the region this afternoon and evening.

The main storm window looks likely to be locally between 2 and 7 p.m., moving west to east. In the immediate DC area — near the ring road — timing may favor the 4-5 p.m. area, more or less.

A few additional showers and thunderstorms, probably of lesser intensity, could occur overnight before the passage of the cold front.

Torrential downpours, heavy lightning and some areas of damaging wind gusts are the main threats of any thunderstorm. An isolated tornado may also develop. As such, the National Weather Service Storm Prediction Center has placed the immediate DC area and locations south or east under a slight Level 2 out of 5 risk for severe storms.

A severe thunderstorm watch will likely be issued for parts of the region this afternoon.

A wild and wonderful sky on Thursday evening, followed by a ball of fire

A heavy air mass is anchored in the region as a cold front approaches from the Ohio River Valley. As the front pushes east it will help showers and thunderstorms develop ahead of it.

Widespread cloudiness this morning has limited temperature-induced instability – the fuel for thunderstorms – so far. Greater instability is developing south of the area and some of it may move north as skies clear up a bit this afternoon. The distance north of the unstable air mass is critical to knowing where the strongest storm activity is developing and spreading.

Relatively strong winds in a river of air aloft, known as the jet stream, along with summer instability below are expected to conspire to allow some storms to become intense. At this point, it looks like the biggest source of fuel for the storms will be near the district and to the south, where the weather service said a severe thunderstorm watch will likely be issued.

Some segments of arc-shaped thunderstorms capable of strong and potentially damaging winds up to around 60 mph are possible. One or two rotating storms, called supercells, can also develop given the stronger winds aloft. Although the tornado threat is low, a brief touchdown cannot be ruled out in a rotating storm. A handful of hail is also possible, although it should not be too extensive or large.

A lack of storm inhibition – sometimes referred to as a “cap” – noted in the Storm Prediction Center discussion could allow showers and storms to develop just about any time, although they are likely to be the most numerous. at the end of the afternoon

The most common risks associated with showers and thunderstorms are heavy rain and lightning. With a very humid air mass in place, torrential downpours are possible.

“The potential for multiple thunderstorm cycles with very high precipitation rates in an air mass characterized by [precipitable water values] more than 2 inches could result in an isolated flood threat throughout this evening,” wrote the weather service office serving our area.

These types of humidity values ​​can result in exceptional precipitation rates of one to three inches per hour. This would lead to some potential for flooding, particularly in urban areas and particularly if storms move repeatedly in the same location.

Although the storms are expected to be rather gradual and random, thus limiting the threat of flooding, some places remain waterlogged due to frequent rains this month. Through Thursday, the district had collected 7.11 inches of rain in July, compared to an average of 4.2. It was the wettest July 17 on record to date.

While the main series of showers and storms are likely to end and move away before sunset, more showers or even a storm are still possible overnight before the front fully passes.

By Saturday morning, considerably drier air will move into the region, setting up a nice start to the weekend.

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