Major, catastrophic flooding hits Texas, at least two people dead as slow-moving storm dumps over 1 100 mm (43 inches) of rain

Major, catastrophic flooding is occurring across much of Southeast Texas, NWS said September 18, a day after Tropical Storm "Imelda" made landfall near Freeport, TX, adding that some areas could see up to 1 000 mm (40 inches) of rain through Friday, September 20. Heavy rain continued into Friday across portions of Southeast Texas and Southwest Louisiana, but rates have finally begun to decrease as the storm started shifting to the ArkLaTex region.

Severe weather and flooding event caused by Tropical Cyclone "Imelda" that began on September 17, 2019 has caused widespread and severe property damage, threatening the loss of life in Brazoria, Chambers, Galveston, Hardin, Harris, Jasper, Jefferson, Liberty, Matagorda, Montgomery, Newton, Orange, and San Jacinto counties and forcing Texas Governor Greg Abbot to declare a state of disaster in listed counties on September 19.

"The depression brought a band of intense thunderstorms between Houston and Beaumont that held nearly stationary for hours on end, dumping prodigious amounts of rain," Weather Underground's Bob Henson said.

"Doppler radar detected winds of up to 90 km/h (56 mph) just above ground level pushing massive amounts of moisture from the Gulf of Mexico into the thunderstorms. Rainfall of 75 – 127 mm (3-5 inches) per hour was falling atop ground already saturated by days of heavy rain."

At least 2 people lost their lives. According to media reports, a person in Jefferson County drowned while trying to move a horse to safety. Another person lost its life in Harris County after a vehicle with several occupants became submerged while attempting to drive through a flooded road.

More than 1 000 people called for rescues as water entered hundreds of homes, KBMT reported, adding that one of the nation’s largest oil refineries, the Exxon Mobil facility in Beaumont, was closed because of the storm.

Imelda's rain forced Houston's George Bush Intercontinental Airport to order a full ground stop around 09:30 local time Thursday. In an update, the airport said that roads leading to the airport are flooded and flights were delayed. "If you have to pick someone up from the airport right now, delay your drive. The airport is open, we have power and restaurants are open, so your passengers will be ok."

At 22:000 PM CDT, September 18, the National Weather Service radar and surface observations showed an area of moderate to locally heavy rainfall in a swath extending from near Beaumont northward to near Tyler, Texas. Some lighter showers were still affecting extreme southwestern portions of Louisiana.

There has been a weakening trend in the rainfall rates compared to earlier this afternoon, NWS said at the time.

Selected preliminary Storm Total Rainfall from 07:00 CDT on September 16 through 21:00 CDT, September 19: 

...TEXAS...
NORTH FORK TAYLORS BAYOU            43.35 in (1 101.09 mm)
MAYHAW BAYOU @ BRUSH ISLAND ROAD    42.64 in (1 083.05 mm)
GREEN POND GULLY                    40.87 in (1 038.09 mm)
LAWHON DETENTION @ DITCH 400        37.91 in (962.91 mm)
FRINT ROAD @ WILLOW MARCH BAYOU     37.40 in (949.96 mm)
HAMSHIRE 4 NNE                      33.58 in (852.93 mm)
EAST FORK SAN JACINTO               29.60 in (751.84 mm)
PEACH CREEK @ SPLENDORA             25.76 in (654.30 mm)
PINE ISLAND BAYOU                   25.21 in (640.33 mm)
SAN BERNARD NWR                     21.69 in (550.92 mm)
ROMAN FOREST 1.9 ENE                21.01 in (533.65 mm)
TRINITY RIVER AT LIBERTY            20.65 in (524.51 mm)
BEAUMONT/PORT ARTHUR RGNL ARPT      20.46 in (519.68 mm)
DAYTON                              19.76 in (501.90 mm)
HUMBLE                              19.59 in (467.58 mm)
CLEVELAND                           18.37 in (466.59 mm)
GALVESTON ARPT                      15.79 in (401.06 mm)
HOUSTON INTERCONTINENTAL ARPT       11.67 in (296.41 mm) 
HOUSTON HOBBY ARPT                  10.91 in (277.11 mm)

Based on their own analysis of damage, AccuWeather estimates the total loss caused by TC Imelda will be $8 billion. The estimate includes damage to homes and businesses, as well as their contents and cars, job and wage losses, farm and crop losses, contamination of drinking water wells, infrastructure damage, auxiliary business losses and the long-term impact from flooding, in addition to the lingering health effects resulting from flooding and the possible disease caused by standing water.

Tropical Depression "Imelda" has dissipated, but its remnants will still bring heavy rain and possible flash flooding to portions of the Southern Plains and Arklatex region today, NWS forecaster Snell noted 07:30 UTC today.

Meanwhile, a low pressure system will make gradual progress from the Rockies, to the northern Plains, to Ontario over the next few days. An associated cold front will push into the Plains today and tonight. This front should lead to thunderstorms in the northern and central Plains both today and Saturday. Some of the storms could be severe, with large hail and damaging winds the primary threats.

The Storm Prediction Center has issued a Slight Risk for severe thunderstorms across the Northern Plains today and the Central Plains Saturday.

Flash flooding will also be possible, especially on Saturday and Saturday Night in portions of the Central Plains as the front begins to interact with lingering moisture from Imelda.

Rainfall amounts in excess of 75 mm (3 inches) are forecast from central Kansas into northern Missouri. This has prompted a Moderate Risk of excessive rainfall to be issued.

Colder air will continue to push through the western states behind the cold front, and this is expected to lead to accumulating snow in the higher elevations of the interior Northwest, particularly in Idaho, Montana and Wyoming above 2 440 m (8 000 feet) elevation.

Winter Weather Advisories have been issued across these regions, where up to a foot of snow is possible.

High temperatures will be as much as 15 – 25 °C (27 – 45 °F) below average in these areas.

Ahead of the cold front, high temperatures will be above average in the Plains and Central U.S., with the warmth spreading to the East Coast this weekend. Temperatures will be most above average in the Great Lakes, with highs into the 80s (°F) and lows in the mid-to-upper 60s (°F) on a widespread basis.

Those temperatures are more typical of average conditions in mid-summer in the region.

Featured image credit: TX Parks & Wildlife