Prediction after the storms, until Tuesday | A Derecho will happen again someday. Will we be ready?
8:47 – After crossing the mountains, the storms rapidly increased
Our storm weather expert Jeff Halverson noted that the leading edge of this gust line intensified as soon as the system reached the eastern side of the mountains, where it was very warm and could get wet air. This is how the Derecho 2012 intensified.
We show this in two satellite images, before and after. The darker red areas show where the strongest thunderstorms are.
Over the mountains:
East side of the mountains:
18:35. – The leading edge of the storm has reached the Beltway.
Everyone in the Beltway should now be clean, not only because it's raining, but because this storm has extremely strong gusts of wind that could cause trees and power lines to collapse
A few reports of damage have already been received – trees in Loudoun County near Leesburg and there was a report on a funnel cloud in Ashburn, and that was definitely in the tornado warning.
6:22 pm – This storm has a massive shelf cloud
We get many Photos of the shelf cloud from our northwestern suburbs. (And while we appreciate the reports once the storm starts, please go in and find a spot outside the windows, which will destroy trees, branches, and power lines.)
– Cynthia Adler (@Cynthia_Adler) May 14, 2018
6:12 pm – Tornado Warning for Reston and the Surrounding Suburbs
A new Tornadowarnung for parts of the counties Loudoun and Fairfax, including Sterling, Reston, Oakton and Great Falls. If you are in one of these areas, please look in a basement or interior without windows. Even if there is no tornado, this part of the storm has dangerously high winds that could cause trees, branches and power lines to collapse.
Tornado Warning including Reston VA, Ashburn VA, Oakton VA to 18:45 EDT pic.twitter.com/KzjxgIaTEM
– NWS DC / Baltimore (@NWS_BaltWash) May 14, 2018  18:05 – Strongest Part of Storm Towards Beltway
A tornado warning remains valid for parts of the counties of Loudoun and Montgomery, including Leesburg and Poolesville, Maryland, until 6:15 pm. The most dangerous part of this squall line is heading southeast towards the Beltway and looks like it will be arriving at around 18:45.
A Severe Thunderstorm Warning is now in effect for much of the DC Metro. No matter where you are, you will be hit by part of this storm.
17:53 – Tornado Warning for Parts of Loudoun, Montgomery Counties
Radar indicates that a tornado may be present in the strongest part of this squall line in Loudoun County. A tornado warning was issued for the storm, which includes Purcellville, Leesburg, Ashburn, Poolesville and Sterling.
If you live in these areas, seek shelter in a basement or interior. Stay away from windows.
Tornado warning including Ashburn VA, Leesburg VA, Sterling VA to 6:15 pm EDT pic.twitter.com/e1TmS6HVky
– NWS DC / Baltimore (@NWS_BaltWash) 14. May 2018
17:35 – New Warnings Include Far-Western Suburbs
The final series of warnings includes most of Loudoun as well as North Fauquier and Northern Prince William. The strongest storm is on the north side of this line, about to roll through the Leesburg area. We would not be surprised to see quarterly hail in this context, along with torrential rains and gusty winds.
17:20 – First Heavy t-storm warning
Expect very large warnings tonight that involve a lot of real estate. That's the kind of storm that will happen in the next few hours. The storms have reached I-81 and are heading southeast at approximately 30 miles per hour.
Not that we think there will be widespread power outages, but keep your phone up forever.
Strive Thunderstorm Warning including Winchester VA, Front Royal VA, Strasbourg VA to 18:00 EDT pic.twitter.com/BINwPO5XRF
– NWS DC / Baltimore (@NWS_BaltWash) May 14, 2018
A severe storm line has formed over East-West Virginia and continues on a path towards the DC area, which arrives between 6 and 8 pm. from west to east. These storms will sweep over the next hour through Martinsburg, Winchester and Strasburg along the Interstate 81 corridor.
445p: It is now becoming reality. Dangerous Storm Line with multiple warnings in EW Va. Still on DMV 6-8p pic.twitter.com/jxAqnrFwvn
– Capital Weather Gear (@capitalweather) May 14, 2018  Some Key Messages About These Storms:
- We see the greatest risk of widespread, damaging winds from the district to the south and west, but everyone should monitor warnings and stay aware of the evening. Harmful winds could be realistic everywhere.
- Loads devices and now secures or moves in loose objects outdoors.
- In addition to storms, torrential rains and dangerous lightning are to be expected in storms.
- Some storms can contain large amounts of hail and even a scattered tornado can not be ruled out
- It's not about whether we see strong to strong storms, it's a question of how widespread and harmful they will be. Stay on the safe side and be on the safe side tonight. When a warning is issued, go into a strong building, away from windows.
Our next update will be around 5:30 pm.
Heavy storms in southwestern Pennsylvania continue to push southeast and have now reached West Maryland, stretching back north through West Virginia. They should arrive between 18 and 20 o'clock in the immediate subway region. from west to east, possibly only at 8:00 pm to 9:00 pm in our eastern areas near Chesapeake Bay.
Satellite image shows an intense storm complex developing northwest of DC. I still think that it happens the metro region 6-8p. Heavy t'Storm clock indeed by 9p. For the full overview see: https://t.co/CgxFbB265t pic.twitter.com/WynB6QHcTV
– Capital Weather Gang (@capitalweather) May 14, 2018
Es It is expected that the threat of harmful winds will persist and potentially become widespread by tonight, "the National Weather Service said in a special statement released just before 3:30 pm
The statement indicated that in addition to the wind threat that the stronger storms can also produce great hail and perhaps a short-lived tornado.
The biggest question at 4 pm is not whether the area will see strong to strong storms, but how extensive and detrimental they will be.
This stormline could meet the criteria of a Derecho after our update at 13:30, which is a fast moving storm line with widespread damaging winds, but it is very unwah himself It is likely that this event will be as intense as the destructive Drecho in June 2012 sweeping through the region. We think that districts and south and west areas are most likely to have the highest concentrations of strong winds.
It would not be a bad time to prepare for possible power outages. Charge your devices and go in or secure loose items outdoors.
Our next update will be around 5pm
2:45 pm. update
The line of storms we are worried about extends from southwest Pennsylvania to eastern Ohio. It is expected that races will take place east-southeast in the coming hours, and the arrival time in the metro area is expected to be between 6pm and 8pm from west to east.