NASA analyses Maryland storm system that caused flooding

NASA looks at historic flooding from slow-moving Maryland storms

NASA analyzed rainfall data from slow-moving storms that triggered flash floods over parts of central Maryland and caused devastating flooding in historic Ellicott City, Maryland.

This image shows instantaneous IMERG-estimated rainfall rates at 8 p.m. EDT on July 30, 2016. It depicts a strong band of heavy rain (an inch per hour in purple areas) extending east-west over north-central Maryland extending southwestward into northern Virginia. CREDIT NASA/JAXA/Hal Pierce

This image shows instantaneous IMERG-estimated rainfall rates at 8 p.m. EDT on July 30, 2016. It depicts a strong band of heavy rain (an inch per hour in purple areas) extending east-west over north-central Maryland extending southwestward into northern Virginia. CREDIT NASA/JAXA/Hal Pierce

A slow-moving line of heavy thunderstorms dumped as much as 6 to 7 inches of rain in about two hours’ time during the evening of Saturday, July 30, over parts of Howard County in central Maryland, resulting in severe local flash flooding.

The hardest hit area was the historic town of Ellicott City, where two people were trapped in their cars and drowned. The town suffered substantial damage to many buildings, numerous cars were tossed about, and around 150 people had to be rescued from the downtown area. The heavy rains and flooding were a result of successive waves of rather slow moving storms that merged over the area.

NOAA’s National Weather Service (NWS) in Baltimore issued a public information statement about the flooding on July 31, calling it “historic heavy rainfall Saturday in Ellicott City.” NWS noted that extremely heavy rain fell and a rain gauge provided by Howard County to the National Weather Service measured 6.5 inches.

A warm, humid air mass, a stationary frontal boundary, and rather weak winds aloft set the stage for the slow-moving storms. Earlier in the afternoon, storms formed up and organized along the Appalachian Mountains before moving slowly out across the Piedmont. The Piedmont is a plateau area between the Atlantic coastal plain and the Appalachians.

This slow-moving line triggered new storms along its leading edge and was eventually overtaken by a second line of successive storms moving out from the Appalachians. The result was a mass of heavy raining thunderstorms across central Maryland that slowing moved eastward before weakening over the northern Chesapeake Bay.

NASA’s Integrated Multi-satellite Retrievals for GPM, or IMERG, is used to make estimates of precipitation from a combination of passive microwave sensors, including the GMI microwave sensor on board the GPM, or Global Precipitation Measurement, mission satellite, and geostationary IR (infrared) data. These data were used to create images and animations at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. GPM is a joint mission between NASA and the Japan Aerospace Exploration Agency.

One image created showed instantaneous IMERG-estimated rainfall rates at 8 p.m. EDT on July 30 (12 a.m. UTC on July 31), 2016. IMERG showed a strong band of heavy rain extending east-west over north-central Maryland extending southwestward into northern Virginia. Within this band, rain rates are generally on the order of an inch per hour with localized areas of higher rates.

IMERG was also used to estimate rainfall totals for the period from July 20 at 4 p.m. EDT (8 p.m. UTC) to July 31 at 6 a.m. EDT (10 a.m. UTC). Rainfall totals across central Maryland were on the order of more than 3 inches (70 mm).

IMERG was also used to estimate rainfall totals for the period from July 30 at 4 p.m. EDT (8 p.m. UTC) to July 31 at 6 a.m. EDT (10 a.m. UTC). Rainfall totals across central Maryland were on the order of more than 70 mm (about 3 inches, shown in brown). The white crosses denote the location of Ellicott City, Md. CREDIT NASA/JAXA/Hal Pierce

IMERG was also used to estimate rainfall totals for the period from July 30 at 4 p.m. EDT (8 p.m. UTC) to July 31 at 6 a.m. EDT (10 a.m. UTC). Rainfall totals across central Maryland were on the order of more than 70 mm (about 3 inches, shown in brown). The white crosses denote the location of Ellicott City, Md. CREDIT NASA/JAXA/Hal Pierce

On Aug. 1, 2016, because of the severity of the flooding, Howard County Maryland Executive Allan H. Kittleman signed an executive order closing a portion of Ellicott City to all but emergency vehicle and pedestrian traffic. For updated information from Howard County, visit:https://www.howardcountymd.gov/.

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Yeah, we got hit with some of that in Poolesville, MD. Didn’t get as much precip as they did tho.
However, we didn’t build our town inside the banks of a river, so we escaped relatively unscathed.
Next we’ll hear that a city built in the desert is having droughts… probably globull warming to blame.

ShrNfr

Funny how when you site your town in the wrong place and then change the local hydrology in a massive fashion that you eventually get nailed, isn’t it? Kinda like the folks who insist on building on sand bars. I’ve seen a lot of those floating in the bay in the 1960s.

They’ll rebuild. This latest flood came nowhere near reaching the high water mark Hurricane Agnes left there. Besides, The Honorable Elijah Cummings has offices there, so it will all get rebuilt for free! Right?

auto

The other thing is the planners’ – and developers’ – complete and utter lack of understanding of a short phrase: –
Flood plain.
It does what it says on the tin.
If there is heavy precipitation upstream, the plains flood.
That’s what they are designed – evolved – to do.
On Flood plains – the plains, sometimes, flood.
Why build there?
Why would you buy there??
Why – oh, why? – would you live there???
Sorry – we have too much building – especially in SE England – on flood plains.
Guess what – Flood Plains – flood!
Auto – not astonished at the greedy house-builders, but at the planning authorities that allow buildings on flood plains – and at the buyers of said – likely underwater – homes . . . .

Also from NASA
Indonesian fires linked to El Nino events
A team of researchers with NASA, several other U.S. institutions note that some fire years are much worse than others—2015, for example, was the worst since 1997—it was so bad the smoke cloud covered a small swath halfway around the equator. Data from both sources revealed a pattern—the worst fires happened during El Niño events.
http://phys.org/news/2016-08-largest-indonesian-linked-el-nino.html
Not to be left behind, this from IPCC
Trees on farms: The missing link in carbon accounting
Agriculture and land-use change accounts for about 24% of the world’s greenhouse gas emissions.
http://phys.org/news/2016-08-trees-farms-link-carbon-accounting.html

Louis

“Agriculture and land-use change accounts for about 24% of the world’s greenhouse gas emissions.”
I guess we should stop farming, stop eating, and stop air conditioning our homes then. Dying of starvation in the summer heat has to be far better than being slowly tortured by the climate-change boogeyman who is supposed spring from his hiding place in the deep oceans at any moment. (/sarc)

Robert from oz

So the once mighty NASA thinks that in a hot year the fires are worse , no wonder they can’t put a person into space .
All that money wasted on drugs and partying .

Robert from oz

I should save them a few billion and years of research and tell them in a cold wet year there will be less forest fires .

The missing link in carbon accounting ? They are still way short.

beng135

Been to Ellicott city — it’s very picturesque, but a classic flood zone, even tighter/steeper than Harpers Ferry, WV.

texasjimbrock

We had a lot of rain in Texas last month. Didn’t flood NASA, though.

Neil Jordan

Here is the link to FEMA’s Flood Insurance Rate Map:
http://map1.msc.fema.gov/idms/IntraList.cgi?displ=wsp/item_24027C0095D.txt
The FIRM view is at:
http://map1.msc.fema.gov/idms/IntraView.cgi?KEY=34367134&IFIT=1
The other half of the panel is at . . .0095F.

sean2829

Ellicott City is only about 5 miles west of where I was located during the storm. We got a pretty good downpour but nothing out of the ordinary and traffic continued moving on I-95 during the storm albeit more slowly than normal. Look at google maps of Ellicott City and main street wanders back and forth across a steep stream that flows through the center of town and at the bottom end of the street, just before those streams join the Patapsco river, there is a confluence of 3 more streams. (Highlight traffic and red dashed lines will show you exactly where the flooding took place). As a result, this town floods a lot.
Ellicott City is one of the oldest cities in Maryland as it sits at the intersection of the coastal plain and the Piedmont. That steep stream running through the center of town was low carbon renewable power for running industry in the 18th and 19th century. It’s only about 10 miles from the port of Baltimore. The proximity to hydro power and ocean transportation was likely its reason for being. When coal power came to prominence, industry left these small flood prone streams behind and moved to the shoreline of Baltimore Harbor, along with power plants that supplied electricity.
Maryland has a lot of picturesque old places like this with exactly the same problems. North of Baltimore, the Jones Falls flooded from the same storm. That happens a lot there. Someone mentioned Harper’s Ferry at the confluence of the Potomac and Shenandoah river, that floods regularly. Point of Rocks, Maryland, about 7-8 miles downstream from Harper’s Ferry suffered 2 “500 year floods” in the same year, once in the winter and once in early fall. After the second flood that year, they decided it not to rebuild the town in the same location. Perhaps it’s time Ellicott City considers a change like this.

I live less than 5 miles as the crow flies from Main St Ellicott City and got only 1/3 the rain they did. Old Towne Ellicott City has some geographical features that made this worse. If you’ll notice the blob of very high rainfall totals, much of it was north and west. That’s bad. That fed three different creeks that merge near Main St., which – of course – is at the bottom of a valley. They merge at the Patapsco River, right at the foot of Main Street. Which just happens to be down stream of a reservoir where, in high rainfall conditions, the sluice gates open. Bad on top of bad on top of bad.
Surprisingly, the WaPo had a very good article on this. The rainfall totals and times are truly eye opening, 2 inches of rain in the first 15 minutes. A solid half hour with an inch of rain every 10 minutes.
https://www.washingtonpost.com/news/capital-weather-gang/wp/2016/08/01/this-is-how-an-off-the-charts-flood-ravaged-ellicott-city/?hpid=hp_no-name_flooding-1115am-rhp%3Ahomepage%2Fstory

Marcus

..”A solid half hour with an inch of rain every 10 minutes.”…For 30i minutes, that would only be 3 inches…”Have you ever been in a Daytona Beach summer storm ?? You get twice that much in less than 10 minutes….But the storm only last 2o minutes at most…, and of course, being above Sea Level..it becomes much needed ground water for the Aquifers..

With all due respect Marcus, I think it probable you failed to read the story I linked to. That’s a prodigious amount of rain in a very short time no matter where you are. I also suspect you may not have read my post, listing several other factors that contributed to the flooding.
By the way, I’ve spent Bike Week at Daytona either corner working or racing since ’94 – Yes, I’ve been in Daytona Beach during some rather serious weather. I was also crew on a charter boat out of Oregon Inlet in NC and have experienced genuine hurricanes.
I was also standing on my porch last Saturday night where (as I mentioned) we got only 1/3 of what hit Ellicott City. Personally, I’d have rather been in the pits or on a corner at DIS during the worst I’ve seen there rather than what I saw this weekend.

Take a look at the totals, though I’m thinking an inch of rain every 10 minutes should be enough to impress anybody.comment image&w=1484
And by my investigation, the worst Daytona has ever seen only ~matches~ what happened to Ellicott City, it doesn’t exceed it.

http://www.srh.noaa.gov/mlb/data.php?file=/summary/Sep2014.txt
-SEPTEMBER 24TH: RECORD RAINFALL OF 6.41 INCHES. PREVIOUS RECORD WAS 4.22 INCHES SET IN 1974.
http://www.news-journalonline.com/news/20140924/record-rains-bring-flooding-to-se-volusia-daytona-beach-areacomment image&w=1484

Eustace Cranch

“Analyses” is a plural noun. “Analyzes” is a verb. I think the latter is what you wanted. Submitted respectfully.

Tucker

Those types of cloudbursts happen regularly it seems in the ridge and valley regions of the northeast USA. I remember a coupe such storms growing up. In one, I believe 1982, we had six inches in 80 minutes. Water was literally laying on the ground with nowhere to go because it couldn’t drain fast enough. Scary. Another around 1970 was similar in potency, maybe worse. These things happen when training of slow moving rain producers happens. Unfortunately this time, the rain hit a more vulnerable area.
One of those, “nothing to see here. Move along” moments. It will happen again and again whether we have global warming or global cooling or a Goldilocks climate.

auto

Tucker
“One of those, “nothing to see here. Move along” moments. It will happen again and again whether we have global warming or global cooling or a Goldilocks climate.”
Right. + a good number.
Doesn’t matter what the climate is – we will still get weather.
Some nice – some not so nice.
like you, I thin we need to live with that weather.
[And – not build on flood plains . . . .]
Auto

beng135

Smethport, PA had over 30″ rain in 4.5 hrs on June 17, 1942. Stationary thunderstorms trapped in a mountain valley.
http://www.accuweather.com/en/weather-blogs/weathermatrix/the-great-smethport-pa-rain-of-1942/16482

Looks like the Tiber Creek is routed under a lot of the buildings near Main
Street, and that Main Street is built mainly along a gully. Just looking at it from Google Earth.
http://www.panoramio.com/photo/31427664?source=wapi&referrer=kh.google.com
Looks like the Tiber Creek was the culprit:
https://www.facebook.com/hocogov/photos/a.171847892862463.33278.131647483549171/1051103878270189/?type=3&theater
I believe this is Tiber Creek and shows high water marks above main street, with 1972 being the highest:
http://www.panoramio.com/photo_explorer#view=photo&position=4475&with_photo_id=85066558&order=date_desc&user=7306875

Looks like there are a bunch of small streams or creeks which run almost parallel to Frederick Rd which turns into Main Street. Hudson Branch, and Tiber Branch and a few other creeks. This flood wasn’t the result of the Patapsco River which flooded in 1972 from Hurricane Agnes.
This shows a bunch of photos of repeated floods if you click through the photos at the bottom of the first pic. I wonder who keeps paying for all the rebuilding:
http://darkroom.baltimoresun.com/2016/07/from-the-vault-historic-floods-in-ellicott-city-maryland/#1

Not to keep harping on this, but I count that Ellicott City has had 15 major floods since 1817:
“The town is prone to flooding from the Patapsco River and Tiber Creek. These floods have had a major impact on the history of the town, often destroying important businesses and killing many. Ellicott City has had major devastating floods in 1817, 1837, 1868, 1901, 1917, 1923, 1938, 1942, 1952, 1956, 1972 (Hurricane Agnes), 1975 (Hurricane Eloise), 1989, 2011 and 2016.[9] Modern floods include the 1868 flood which washed away 14 houses, killing 39 to 43 (accounts vary) in and around Ellicott City….”
As my Dad always said; “Never build on a flood plain”.
Ref: Wikipedia

Retired_Engineer_Jim

But this rainstorm and subsequent flooding was “historic”. It says so.

POQ

On the 9th of August, 1843,( Thetford, Norfolk}, like many other places in the neighbourhood, suffered severely from a dreadful STORM of thunder, lightning, hail, rain, and wind. For about twenty-five minutes, between six and seven in the evening, rain and hail descended in torrents, and most of the windows that faced the hurricane were broken. Many of the cellars were filled with water, and some of the warehouses and shops were inundated to the depth of two feet. When the coach came in from Lynn, the horses, in passing through Bridge street, were up to their chests in water. In various parts of the town, walls were thrown down by the immense weight of water pressing against them; and in the surrounding country, the gardens and corn fields sustained great injury. Many of the hailstones, or rather pieces of ice, were upwards of 1¼ inch square, and after the storm, more than 100 sparrows were picked up dead in the garden of W. Clarke, Esq. Similar storms happened in the preceding and in the same month, in various parts of the kingdom.
Damned Humans and their Industrial Revolution (sarc)

AllyKat

It is a bad site, assuming you DON’T want flooding. The sewer systems are probably inadequate for high rainfall, just like most cities’ systems. Über developed. Floodplain+inadequate drainage+increased runoff=great big flood. Places like this just get hit all the time. The only way to “fight it” is to improve drainage or move to a different site.
It is only shocking if a floodplain does NOT flood during a large melt or rain event. Otherwise it is business as usual.

Can they get flood insurance through FEMA? If so that is crazy.