The extreme heat and humidity have the atmosphere primed to potentially produce severe storms capable of damaging winds late Saturday afternoon into evening. The storm risk comes as the strong high pressure primarily responsible for the heat wave, and for squashing rain chances the past several days, starts to weaken a bit.
Scattered storms could start to develop in the DC area anytime after 3 or 4 p.m. However, there is some question if the most numerous storms will occur from roughly 3 to 8 p.m. versus more like 6 to 11 p.m. That difference could, obviously, have a big impact on conditions during fireworks. The best we can do is try to narrow down the timing as the data allows and the day progresses.
It's important to note that while there is a reasonable chance any given location sees at least one storm come through at some point, it's not impossible the activity ends up scattered enough to miss some spots.
Heavy rain and frequent lightning are likely with any storms that develop, in addition to potential for severe winds. The National Weather Service has placed most of the DC region under a Level 3 of 5 severe risk because of the threat of scattered damaging wind gusts near or over 60 mph, and a couple of isolated destructive gusts of 70 to 75 mph.
"The level of storm fuel this afternoon is expected to be exceptionally high, to the point where we have an enhanced probability of very intense storms. The greatest concerns will be intense lightning and damaging wind gusts, with a few of these potentially reaching destructive wind speeds near or greater than 70 mph," said Capital Weather's severe weather expert Jeff Halverson. "People outdoors should have plans to stay notified of storm warnings and, if a storm develops, take quick shelter away from trees, while those indoors should move to the lowest floor of the building and away from windows."
Safety tips
With the extreme heat and severe storm threat, the Weather Service has asked media to pass along these important safety tips:
- Remain hydrated by drinking water and avoiding alcohol. Beverages with electrolytes can also protect against heat stress. The body loses 1 to 2 liters (up to 68 oz or 4 water bottles) of water per hour when heat index values are between 105-110 degrees.
- Drink plenty of water (every 20-30 mins) even if you're not thirsty.
- Take regular breaks in the shade or in cool spaces
- Wear lightweight and loose-fitting, light-colored clothing.
- Apply sunscreen SPF 30 or higher every 2 hours.
- Look Before You Lock!!!! Don't forget anyone in a hot car. On average, 38 kids die each year by being left in a vehicle. 88% are under 3 years old. 54% are forgotten by a caregiver. https://weather.gov/safety/heat-children-pets.
- Have a way to get warning via phone, tv, radio, or internet. This includes downloading trustworthy weather apps for those headed to many of the festivities around the region.
