On June 5, Montgomery County faced something unusual but not unprecedented in our county: two confirmed EF-1 tornadoes. On June 6, MoCo 360 quoted a Montgomery County emergency management official as saying, “We had no forewarning whatsoever that the storm was coming.” I’m not sure how much warning this official expected to receive, but the county actually was well warned of the June 5 tornado threat, given the nature of tornadoes.
A tornado isn’t a hurricane or winter storm that normally can be warned of days or even hours in advance. Hurricanes and winter storms are significantly larger and slower-developing than tornadoes, which means warnings about those impending storms have a significantly longer lead time than for a tornado. The National Weather Service (NWS) in 2023 said the average lead time for tornado warnings was nine minutes, with 13 minutes being the goal.
On June 5, the NWS first issued a tornado warning for a part of the county at 6:33 p.m., and a tornado first hit a part of the county at 7:01 p.m. This actually is a very good advance warning for a tornado. At 7:22 p.m., for the first time in the history of the NWS’s Sterling, Virginia, Weather Forecast Office (which is responsible for the entirety of the Washington, D.C., and Baltimore metro areas), the NWS added a “Particularly Dangerous Situation” (PDS) tag to a tornado warning. These tags are rare, and for good reason. They are designed to get our attention and distinguish this warning from other tornado warnings. If every tornado warning were treated the same way, members of the public might judge the situation based on the last time they received the warning, and most people who receive such warnings don’t get hit by a tornado.
At the time of the PDS warning, there was a confirmed tornado on the ground near Poolesville and it was moving east at 20 mph. Another related tornado ended up hitting Gaithersburg between 7:40 and 7:45 (on June 13, the NWS recharacterized the Gaithersburg tornado as separate from the Poolesville tornado). You’ll rarely get hours of warning of a tornado, so hopefully we’ll be able to respond to tornado warnings with less notice than for other severe weather events, like we did on June 5.
The NWS determined that both tornadoes were 150 yards wide. Considering how much wider the area warned (“the warning box”) was than the tornadoes, it appears that the right people received warnings. If too many people outside of the warning boxes were to receive a warning without experiencing or being very close to a tornado, they may not take the next tornado warning seriously. We do not want any Takoma Park residents to think that they need to go to their basements because of a tornado warning for Poolesville or vice versa. For two EF-1 tornadoes to move through a highly populated county like Montgomery County, having only five injuries and no deaths was an impressive success and a sign that county residents heeded the warnings that they were given.
Are we at an increased risk of having more tornadoes because of climate change? We really don’t know. Climate is to weather what personality is to mood. While climate change is certainly an issue that causes more extreme weather, more research is needed to prove that climate change has caused an increase in tornadoes.
Advancements in the ability to detect tornadoes, notably the installation of dual polarization radar in the NWS radar network in 2012 (which enables radar alone to confirm the presence of a tornado on the ground in some circumstances), have been crucial in improving tornado forecasting, but also have increased the number of tornadoes detected. It will take more research to determine how much of the increase in the number of detected tornadoes was caused by technological advances and how much was due to climate change.
Rockville resident Andrew Naimon, a Montgomery County native, has a bachelor of science degree in meteorology and atmospheric science from Pennsylvania State University.