Maryland flash flood hits with frightening power
Another week, another extreme flash flood event.
This time it's Ellicott City, Maryland. Rainfall rates reached an incredible 4.56" in one hour, and reports of up to 8" of rain in just 3 hours produced a devastating flash flood that killed 2 people in the Baltimore suburb Saturday night.
The scenes in this 2nd floor eatery on a busy Saturday night are nothing short of frightening. The terrified patrons narrate as the flash flood sweeps cars, and people down the street in Ellicott City.
The Baltimore-Washington D.C. NWS office calls the flood event historic, and calculates a 1-in-1,000 year event.
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Public Information Statement
National Weather Service Baltimore MD/Washington DC
1216 PM EDT Sun Jul 31 2016
...Historic heavy rainfall Saturday in Ellicott City...
Extremely heavy rain fell Saturday evening in Ellicott City,
Maryland. Thanks to rain gauge data from Ellicott City, which is
provided by Howard County to the National Weather Service, we have
detailed information on how quickly the heavy rain fell.
The following table lists the rain that was recorded by this
gauge. Note that the gauge reports in increments of 0.04 inch:
DURATION AMOUNT TIMEFRAME
----------------------------------------
1 minute ..0.20 from 7:51pm-7:52pm
5 minutes ..0.80 from 7:50pm-7:55pm
10 minutes..1.44 from 7:50pm-8:00pm
15 minutes..2.04 from 7:46pm-8:01pm
20 minutes..2.48 from 7:44pm-8:04pm
30 minutes..3.16 from 7:36pm-8:06pm
60 minutes..4.56 from 7:30pm-8:30pm
90 minutes..5.52 from 7:00pm-8:30pm
2 hours.....5.92 from 6:45pm-8:45pm
The storm total at Ellicott City was recorded as 6.50 inches.
The nearest point precipitation frequency estimates in NOAA Atlas
14 come from Woodstock, which is approximately five miles away.
Based on this data, the precipitation amounts with duration 10
minutes to 2 hours statistically have a less than one tenth of
one percent (less than 0.1 percent) chance of occurring in any
given year.
This data is preliminary and is subject to correction.
Climate change role?
Attribution studies will no doubt be conducted on this extreme rainfall event. At first blush the incredible rainfall rates of 4.5 inches in just one hour suggest the fingerprints of a warmer climate, juiced with higher levels of atmospheric water vapor.
Longer term data shows how extreme rainfall events increasing fastest in the Midwest and eastern U.S..
It is apparent to this meteorologist that our infrastructure is increasingly less capable of handling the super-charged extreme rainfall events we're observing in this new evolving climate era.