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17:55 – Storms crossing the southern half of the area
Showers and storms have merged in the southern half of the region in the last hour or so. The storms were particularly brave in the south of Md., Where an important warning of violent thunderstorm takes place until 19:00. This mainly concerns the risk of isolated and damaging winds.
This activity will continue to sink south and east during the next hour. Moderate rain may remain for a while, especially in southern Maryland. Otherwise, it will rain only light rain or intermittent showers depending on your location. The showers will continue to cross the area in the evening before subsiding later.
4:05 pm – Storms hit southwest Washington. Coverage in the evening can be random.
The radar in the immediate area of Washington is calm, but there are showers and storms in central and west-central Virginia heading northeast. Some of these could affect our western and southwestern regions (around Fauquier and Prince William Counties) over the next hour and perhaps closer to the immediate metropolitan area. . For now, they are not severe, but may contain brief heavy rain and gusty winds.
In general, we continue to believe that storms should generally remain below what is considered severe (winds of at least 58 km / h and / or hail) and should be intermittent in the region. But an isolated violent storm can still not be ruled out early tonight, especially in our southernmost regions.
And even our northern suburbs could see a bit of a storm. There is a storm in northern Maryland between Hagerstown and Frederick heading east.
Original article from the beginning of the afternoon
Temperatures above 80 degrees this afternoon should warm enough the atmosphere to cause scattered showers and thunderstorms as a disturbance enters the region tonight.
Although we do not expect widespread severe weather, some storms could be strong, even extreme, especially along the southern periphery of the region near D.C.
The main threats would be strong gusts, a small hail and short, heavy downpours. The most likely time will be between 16h and 19h. in our western regions, from 5 pm to 8 pm in the immediate vicinity and from 6 pm to 9 pm in our eastern regions.
Storm dashboard
Approximate arrival time for any storm:
- West of the ring road: 4 pm to 7 pm
- Around the ring road: from 5 pm to 8 pm
- East of the ring road: 6 pm to 9 pm
Chance of measurable precipitation in any location: 65% south of Beltway 45% north of Beltway.
Movement and duration of the storm: from west to east, for about 45 minutes, no matter where.
Probable effects: heavy rain, lightning, gusty winds.
Possible storm effects: noxious winds, small hail.
Very small chance of: An isolated tornado, a big hail.
Precipitation potential: average 0.1 to 0.5 inches, further south, but highly variable. Localized amounts of 1 to 2 inches are possible.
Rainfall prediction from the high resolution NAM model. Note that this is only a forecasting model that gives a general idea of what might happen, but the current precipitation pattern will differ from it.
Discussion
The risk of a more intense and widespread storm increases as you head south, especially in central Virginia and southern Maryland late this afternoon and especially tonight. This area is in a marginal risk zone (level 1 of 5) for extreme weather conditions and extends as far north as the district. The risk increases slightly (level 2 out of 5) in the Richmond-Petersburg area and in the south.
There is significant wind shear (increasing wind speed with altitude) in the area, which can help withstand storms and generate strong winds. A little more heat than expected could push the immediate Washington area into an unstable atmosphere to allow longer, organized storms to last.
Sunday, it appeared that the most unstable air mass would be in our south; but the predictions of the morning computer model have changed their tone. The example below, taken from the North American high resolution model, suggests that pockets of moderate instability (red regions) will develop in the district late this afternoon.
Prediction of instability levels, also called potential energy available by convection, from the high resolution NAM model. The orange and red areas show the highest levels. (StormVistaWxModels.com)
As the immediate area of Washington is at the northern limit of where strong storms are possible, forecasts are difficult. Below you will find simulated radar snapshots in the early evening from two of the high resolution models (High Resolution NAM, High and Low HRRR). The stormy activity cover extends as far north as the center of Maryland and corresponds well to the north expanse of unstable air shown in the image above. .
The high-resolution NAM model predicts heavy storms in the area Monday night, with the highest concentration south of Washington. (WeatherBell.com)
We do not expect a line of rain gusts or storms, because the approaching cold front is a slow motion that does not have much momentum behind. Instead, there should be some pockets of stormy cells and clusters, which could contain heavy rains and high winds.
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