Hot/Humid Weather + Cold Front = Trouble

NOAA's Severe Weather Outlook for June 19

A large portion of the DC Metro Area is under an “enhanced risk” for severe weather today as a cold front heads eastward, says NOAA’s Storm Prediction Center.  Given how dry June has been, any rain would be welcome, but not dangerous or destructive thunderstorms.  A thunderstorm becomes severe when it contains at least one of the following: wind gusts in excess of 58 mph, hail 1” in diameter or greater, or a tornado.  Heavy rain and lightning make a thunderstorm dangerous, but not “severe” per se.  

A severe thunderstorm “watch” is issued when severe weather is expected in a particular region during a particular time.  A “warning” is issued for a smaller region (such as a county) when said weather condition is either occurring or is imminent.  Also, a tornado warning issued instead of a severe thunderstorm warning when a tornado is occurring.  

June is one of the more active severe weather months in the Mid-Atlantic Region.  One of Maryland’s strongest tornado on record was the Frostburg F4 that occurred on June 2, 1998.  More recently, several tornadoes developed in the DC Metro Area as part of a massive severe weather outbreak on June 4, 2008.

There hasn’t been much active weather, locally, so far this month.  This month has also been warmer than average. While Washingtonians have had five days of 90° heat so far this June, that isn’t a high number for the Nation’s Capital.  Washingtonians have experienced some sweltering Junes in recent years, with four Junes since 2010 having at least 10 days at or above 90°.  The record for consecutive June days at/above 90° in Washington, D.C. is 14, which occurred in 1994.  The last cooler than average June in Washington, D.C. was in 2009.

This afternoon’s severe weather potential is significant.  It’s important to quickly seek shelter in an interior room away from windows should threatening weather approach.  My colleagues and I on the WUSA9 Weather Team will keep you posted on the latest weather watches and warnings this afternoon and evening.