may 27th 2018 destructive flash flooding in ellicott city

On the afternoon of May 2th 2018, multiple rounds of extremely heavy rain yet again tracked over central Howard county. These thunderstorms came after an already wet start to the year so the area was already primed for flooding. This was a fairly well forecasted event with a flash flood watch being issued earlier that morning many hours ahead of the rain. At 3:19pm, things began to rapidly worsen with a flood warning being issued. In total, over 1,100 911 calls were reported across howard county due to flooding or storm damage.

Below is a radar loop from 2:46pm until 4:26pm, when the first round of torrential rain enveloped Ellicott City. This immediately prompted the issuance of a flash flood warning, and the first wave of flash flooding. 

A second round of very heavy rain occured from about 4:30 until 6:15 seen in the radar loop below. This prompted an upgrade to a flash flood emergency as a second, more devastating wave of flooding swept through the city. at 5:41pm, this statement was issued by NWS:

"At 538 PM EDT, there have been numerous reports of significant flash flooding, roads flooded, streams flooded, and flood damage throughout the area. HEAVY RAIN HAS MOVED BACK INTO THIS AREA. THOSE CURRENTLY RESPONDING TO EARLIER FLASH FLOODING MUST SEEK HIGHER GROUND IMMEDIATELY AS A NEW ROUND OF FLOODING IS IMMINENT! THIS NEW FLOODING COULD BE MORE SIGNIFICANT THAN THE INITIAL ROUND! YOU MUST GO TO THE HIGHEST POSSIBLE LOCATION IMMEDIATELY AND STAY AWAY FROM ANYWHERE WHERE THERE IS WATER OR COULD BE WATER!!!

​ This is a FLASH FLOOD EMERGENCY for Ellicott City and Catonsville. This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER GROUND NOW!"

At 6:20pm, an even stronger worded flash flood emergency statement was issued :

"At 620 PM EDT, numerous reports of significant flash flooding have been reported, especially in Ellicott City. ANOTHER ROUND OF HEAVY RAIN IS MOVING BACK INTO THIS AREA. EVEN THOUGH RAIN HAS RECENTLY DECREASED, RESPONDERS AND LOCALS WHO ARE IN ELLICOTT CITY MUST RETURN TO HIGHER GROUND IMMEDIATELY! A THIRD ROUND OF FLOODING IS IMMINENT! IF YOU ARE NOT IN THE AREA, STAY AWAY! THIS IS A CATASTROPHIC AND LIFE-THREATENING EXTREMELY DANGEROUS SITUATION! YOU MUST TAKE ACTION NOW AND STAY AWAY FROM ANYWHERE WHERE WATER IS OR COULD BE'!"

Overall, rainfall amounts were similar to what occured in 2016, with a widespread 2-4" across the northern 2/3 of the county, with a localized area of 5-12" falling over Ellicott City.

The rainfall at the given time intervals were as follows:

1 min: 0.16"
5 min: 0.56"
10 min: 0.96"
15 min: 1.44"
30 min: 1.84" (from 3:53-4:22 and again from 5:20-5:50)
60 min: 2.68" (From 3:20-4:20) and 2.84" (From 5:00-6:00)
2 hr: 5.00"
3 hr: 6.56"

Unfortunately, one person, Eddison Hermond, age 39, was killed during the first wave of the flood while trying to help a woman who was seeking help. Many buildings were severely damaged, and some were destroyed and had to be rebuilt. Additionally, dozens of cars had flood damage as they were washed down the roads. Also of note, is that the Hudson branch has a flood stage at 247 feet. Water levels during this flood rose an additional 4-5 FEET topping major flood stage which is 260 feet.

Forecaster Jack

Photo/GIF credit 1, 2 , and 3: NWS Sterling