To the north, the storm with heavy downpours and lightning was moving toward western Fairfax and western Montgomery counties. They are not severe but may intensify as they move eastward. They should arrive at the Beltway between 5:45 and 6 p.m.
4:40pm — Line up Storm heading west, approaching Warrenton and Leesburg
A severe thunderstorm warning was in place for much of Loudoun and central and northern Fauquier County, with a storm line stretching from south of Hagerstown to south of Charlottesville. The storm is expected to reach Leesburg and Warrenton within the next 30 minutes and could contain damaging wind gusts of up to 60 mph. They were traveling east at about 35 mph and should reach Montgomery and Fairfax counties just after 5 p.m. and the Beltway area between 5:30 and 6:00 p.m.
We will post another update between 5:15 and 5:30 p.m.
The Washington area is in the final throes of one of the worst heat waves on record, with temperatures reaching 100 or above for the fourth consecutive day on Wednesday, a record high. Sudden outs are possible as severe thunderstorms are possible Wednesday afternoon into evening.
An eastward-moving cold front is colliding with entrenched heat and moisture and is poised to produce a large number of storms, some of which could become quite intense.
Because of the threat, the National Weather Service has issued a severe thunderstorm warning until 10 p.m., with “locally damaging wind gusts” of up to 70 mph possible, the National Weather Service said.
A watch means preparedness for the possibility of severe storms, but it's not a guarantee. Keep an eye on the weather if there are severe thunderstorms warn Issued for your location, please seek shelter.
In addition to strong winds, storms can produce heavy downpours and frequent lightning. The possibility of heavy rain prompted the Bureau of Meteorology to also issue a flood warning, which remains in effect until midnight.
“Thunderstorms this afternoon and evening may result in heavy rainfall in excess of 2 inches per hour,” the weather service wrote. “Flash flooding is possible in flood-prone cities and suburbs if repeated or prolonged thunderstorms develop locally.”
By mid-afternoon, temperatures climbed to nearly 100 degrees, and storms were already developing near the Blue Ridge and were expected to push eastward by late afternoon into the evening.
Because some storms may be slow-moving, flooding is possible in some areas despite drought conditions across much of the region in recent weeks.
The storms will eventually help dissipate the record heat.
Storm Potential Introduction
- Storm time: Maximum storm coverage should be at 9pm, moving from west to east.
- Rainfall potential: The amount varies widely, but should average between 0.5 and 1.0 inches. Areas subject to repeated downpours may receive 2 to 4 inches of rain in a matter of hours, posing a threat of flooding.
- Wind threat: Scattered damaging wind gusts could bring down trees and utility lines and cause power outages.
- flood: Flood-prone creeks and streams and poorly drained areas are most vulnerable.
storm discussion
Wednesday's storm threat comes with the arrival of a long-awaited cold front and the end of a severe heat wave.
High-resolution models predict the first storms will develop over the mountains to our west, while the storm group, or short arc, will push eastward. Any early afternoon storms will likely target areas to our north first before spreading to areas to the south later, with a focus likely in the evening.
In the upper levels, disturbances in the upper-level airflow are lifting air, possibly more intensely and more widely than in the past few days.
Our area may be placed under a severe thunderstorm watch by the Bureau of Meteorology's Storm Prediction Center. We are in a Level 2 (out of 5) risk area for severe storms.
The threat of flooding arises from several factors. First, recurring storms are possible for a few hours later today. Secondly, the moisture content in the deep atmosphere is very large. Third, deep warm air masses facilitate the efficient development of heavy rainfall, even in storms that do not meet strict official standards for high winds and hail. Fourth, the threshold for flash flooding today is lower for those areas that have been soaked over the past few days.
The other biggest threat is wind damage, caused by straight-line localized explosions called downbursts. In this type of air mass environment, cells clogged with rain can suddenly release torrents that drag the air downward. Part of the rain is cooled by evaporation, further accelerating its descent; these bubbles violently impact the surface. Some wind gusts could reach 60 to 80 mph.
Heat wave continues
Just before 10 a.m. Wednesday, temperatures rose above 90 degrees for the fifth day in a row and the 29th time this summer, after an overnight low of 83 degrees. high temperature.
Sunday, Monday and Tuesday hit consecutive record highs of 101, 102 and 104, the hottest records since the dust storm began. Wednesday's high of at least 100 points was only the third of four consecutive times to reach or exceed century-level highs; the first two were in 1930 and 2012.
Tuesday's average temperature (the average of the day's high and low temperatures) was 92 degrees, the fifth-warmest day since records began in 1872.
In the past four weeks, there have been 17 days with temperatures of at least 95 degrees, tying the four-week high on record.
This summer was the hottest on record, with days at least 90, 95, 98 and 100 among the hottest.
Temperatures will become milder once the cold front moves in Wednesday night, but summer high temperatures are still expected to reach the 80s to near 90s over the next few days.
