National Weather Service United States Department of Commerce

South Texas Heavy Rainfall - September 2-16, 2018

Corpus Christi - Courtesy Corpus Christi Fire Department AERO Team

In a little less than a week, portions of South Texas went from drought to deluge. While September tends to be one of the wetter months of the year, the combination of an upper level trough and a strong tropical wave (which nearly became a depression) brought heavy rainfall to the region. The heavy rainfall began around September 2nd, and continued off and on through the afternoon of September 16th. This summary will mainly focus on the period September 8th through September 16th, which was when the heaviest precipitation occurred. This extended period of heavy rainfall resulted in widespread flash flooding and significant river flooding. This event also eliminated nearly all of the on-going drought conditions over South Texas.

Plentiful moisture from the Gulf of Mexico and the Pacific Ocean combined with a slow-moving upper level trough axis on Sept 2nd and 3rd. This resulted in widespread 2 to 4 inch rainfall amounts over Western Webb County, with 1 to 3 inch amounts farther north over the Nueces, Frio and Rio Grande River basins. Due to the fact that moderate to extreme drought conditions were observed, much of this rainfall was quickly absorbed by the dry soils in the basin. However, that was just the beginning of the heavy rainfall.

By the morning of Saturday, September 8th, a frontal boundary began to move into South Central Texas, helped in part by the remnants of Tropical Storm Gordon. The September 8th morning soundings from Del Rio and Corpus Christi were already showing very high moisture values, with the Del Rio sounding depicting a nearly saturated layer over 25,000 feet deep. On top of that, upper air analyses showed an upper level trough, with a diffluent area over South Central Texas. The upper forcing, combining with the surface forcing of the front and plentiful moisture resulted in widespread heavy rainfall over South Texas, including the northern portions of the Rio Grande, Nueces and Frio River basins north of the area.

By the morning of Sunday, September 9th, the upper forcing and surface boundary had moved into South Texas. The morning soundings at Corpus Christi and Del Rio continued to show high moisture values. Now, with the focusing mechanisms more over South Texas than farther north in the Texas Hill Country, heavy rainfall was being observed over South Texas. Flash flood warnings were already being issued for La Salle and McMullen Counties where 2 to 5 inches of rain had occurred overnight.

KCRP Radar Loop of Base Reflectivity - September 13, 2018 410 PM CDT through September 16, 2018 658 PM CDT

With the upper level support and front now over South Texas (and expected to move little over the next few days), areas of moderate to heavy rainfall began to occur over South Texas, especially from September 9th through September 12th. The focus of the heavy rainfall gradually shifted south and east, as the frontal boundary and slow-moving upper disturbance moved closer toward the coast. By the morning of September 12th, three day rainfall totals of 2 or more inches were observed over most of South Texas, with isolated amounts of more than 8 inches over extreme Southern Jim Wells County and as well as Eastern Nueces County, including portions of Corpus Christi. The heavy rainfall over Nueces Country during the evening and overnight periods on September 11th and 12th brought moderate flooding on the Oso Creek. Also, Flash Flood warnings were issued for portions of South Texas, including the city of Laredo. Water rescues were reported in the city of Laredo during the early morning hours of September 10th, as anywhere from 3 to more than 9 inches of rainfall was reported by cooperative observers in and near the city.

Between Rockport and Aransas Pass
Photo Credit: Andrea Shetters

By the morning of Wednesday September 12th, 2018, the upper trough axis had moved just east of South Texas, with the frontal boundary hugging the coastal area. Rainfall amounts for the week ending on the morning of September 12th showed widespread rainfall amounts of four or more inches, with some areas reporting from 8 to more than 12 inches over the Brush Country and Coastal Bend. Because the soils were very saturated over South Texas and, with the heavy rainfall over the Texas Hill Country previously mentioned over the past weekend, rivers and creeks continued to rise.

Although the upper level support for the heavy rainfall was moving east and the frontal boundary began to dissipate, more heavy rainfall was on the horizon. By Sunday September 9th, the National Hurricane Center was monitoring a tropical wave currently in the northwestern Caribbean sea. Initially, this wave had a 20% chance of development over the Gulf of Mexico. However, by Tuesday afternoon, September 11th, the Hurricane Center increased its probability to 70% of this wave developing into a tropical depression. Based on the satellite imagery that afternoon, it certainly looked as if the tropical wave was becoming more organized. However, by Wednesday the wave was not showing signs of organization, as drier air in the mid and upper levels weakened the system. The tropical wave approached the Middle Texas Coast on Friday September 14th, nearly becoming a tropical depression as it moved into South Texas that afternoon.

However, an organized tropical system is not needed to produce hazardous and high impact weather over an area. The tropical wave was rich in moisture, and was completely capable of producing widespread heavy rainfall and flooding in South Texas. Bands of very heavy rainfall moved into the area, starting Friday morning and continued through Saturday evening. Widespread flooding was reported, especially over the coastal counties of South Texas including the cities of Corpus Christi, Portland, Ingleside and other coastal locations. Flooding was not as widespread farther inland on Friday and Saturday, but nevertheless occasional moderate to heavy rainfall occurred over inland areas. By the afternoon of Sunday, September 16th, rainfall began to push farther north and west as the remnants of the tropical low moved farther away from South Texas and into Northeast Mexico.

Annaville - Photo Credit: Johnny Herrera

By Sunday morning September 16th, some coastal areas as well as southern-most portions of Jim Wells and Duval Counties had received 10 to 20 inches of precipitation. Most of South Texas received at least 4 inches of precipitation with this week-long event. All of the excess precipitation resulted in river flooding over most South Texas rivers, with reservoir levels rising over the area. In fact, so much rainfall was observed in the Nueces River Basin that Lake Corpus Christi filled to capacity, resulting in reservoir releases and river rises downstream in Bluntzer and Calallen. Unfortunately, Choke Canyon Dam did not see a large increase in reservoir levels. With water continuing to move into the lake for several days after the event, Wesley Seale Dam continued to release water days after the event. Finally, the heavy rainfall event ended drought conditions over South Texas. Prior to the heavy rainfall, some locations over the Rio Grande Plains and Brush Country were experiencing anywhere from moderate to extreme drought conditions. By the end of this event, the drought was eliminated, with only a few areas still experiencing abnormally dry conditions.

Observed Select Rainfall Reports from 9/1/18 - 9/17/18
16-day Observed Rainfall
South Texas Storm Total Rainfall from 9/1/18 - 9/17/18
15-day Observed Rainfall
Nueces County Storm Total Rainfall from 9/1/18 - 9/17/18
15-day Observed Rainfall
Victoria County Storm Total Rainfall from 9/1/18 - 9/17/18
15-day Observed Rainfall
Webb County Storm Total Rainfall from 9/1/18 - 9/17/18
15-day Observed Rainfall

Observed and forecast river stages as of 9/18/18.

This section will be updated later as flooding continues.
(Click each image below to view the full-size image)
On the graphs below, a yellow line represents caution stage, orange is minor flood stage, red is moderate flood stage, and purple is major flood stage.
Nueces River at Cotulla Nueces River at Tilden Nueces River at Three Rivers
Frio River at Tilden Atascosa River at Whitsett Rio Grande River at Laredo
Guadalupe River at Victoria Guadalupe River at Bloomington San Antonio River at Goliad
Mission River at Refugio Oso Creek in Corpus Christi Copano Creek at Refugio
GOES-East CONUS IR Loop - September 13, 2018 402 PM CDT through September 16, 2018 657 PM CDT
PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE CORPUS CHRISTI TX
255 PM CDT MON SEP 17 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1201 AM     FLOOD            CORPUS CHRISTI          27.71N  97.29W
09/15/2018                   NUECES             TX   EMERGENCY MNGR

            HIGH WATER REPORTED AT WATER ST/BORNE AND WATER ST/PARK
            INTERSECTIONS, AYERS AT SIX POINTS, AND ALONG S. STAPLES
            BETWEEN AYERS AND MORGAN (CORPUS CHRISTI WEBEOC)

1214 AM     FLOOD            CORPUS CHRISTI          27.71N  97.29W
09/15/2018                   NUECES             TX   EMERGENCY MNGR

            SOUTH STAPLES AT AGNES FLOODED (CORPUS CHRISTI WEBEOC)

1257 AM     FLOOD            LAMAR                   28.14N  97.01W
09/15/2018                   ARANSAS            TX   LAW ENFORCEMENT

            ARANSAS S.O. REPORTED HIGH WATER ALONG LAMAR BEACH ROAD
            TO 12TH ST, AND ALONG PALMETTO ST FROM HAGY DRIVE TO 8TH
            ST. ONLY HIGH PROFILE VEHICLES ARE ABLE TO MOVE ACROSS
            THE WATER.

0112 AM     FLOOD            CORPUS CHRISTI          27.71N  97.29W
09/15/2018                   NUECES             TX   LAW ENFORCEMENT

            MULTIPLE STREET/ROAD CLOSURES THROUGHOUT THE CITY OF
            CORPUS CHRISTI, INCLUDING: 7530 WEBER RD, HIGHWAY 286 TO
            FM 70, AND CR 28 TO CR 57.

0150 AM     FLOOD            ROBSTOWN                27.80N  97.66W
09/15/2018                   NUECES             TX   PUBLIC

            PUBLIC REPORTED FLOODING IN AVE J IN ROBSTOWN FROM
            PICKER LN TO PAST BOSQUEZ ST NEAR THE ROBSTOWN HIGH
            SCHOOL.

0312 AM     NON-TSTM WND GST PADRE BALLI PARK        27.58N  97.22W
09/15/2018  M42 MPH          GMZ250             TX   NOS

            42 MPH WIND GUST MEASURED AT BOB HALL PIER

0645 AM     FLOOD            2 NNE ODEM              27.97N  97.57W
09/15/2018                   SAN PATRICIO       TX   DEPT OF HIGHWAYS

            ROAD CLOSURE FM 1944 BETWEEN U.S. HIGHWAY 77 AND
            SODVILLE ROAD (TEXAS DEPARTMENT OF TRANSPORATION.
            DRIVETEXAS.ORG.) LATITUDE/LONGITUDE MARKS APPROXIMATE
            POSITION OF FM 1944/U.S. 77 INTERSECTION.

0722 AM     FLOOD            J G GONZALES COLONIA    28.02N  97.51W
09/15/2018                   SAN PATRICIO       TX   DEPT OF HIGHWAYS

            ROAD CLOSURE SODVILLE RD. BETWEEN 82A AND VILLARREL ST.
            LATITUDE/LONGITUDE MARKS APPROXIMATE POSITION OF
            SODVILLE RD./VILLARREL ST INTERSECTION.

0730 AM     FLOOD            1 W TAFT                27.98N  97.40W
09/15/2018                   SAN PATRICIO       TX   DEPT OF HIGHWAYS

            ROAD CLOSURE DAVIS RD BETWEEN MEXICO ST. AND RAILROAD
            AVE (TEXAS DEPARTMENT OF TRANSPORTATION.
            DRIVETEXAS.ORG.) LATITUDE/LONGITUDE MARKS APPROXIMATE
            POSITION OF DAVIS RD/RAILROAD AVE INTERSECTION.

0738 AM     FLOOD            4 SSW SAN PEDRO         27.73N  97.71W
09/15/2018                   NUECES             TX   DEPT OF HIGHWAYS

            ROAD CLOSURE FM 2826 BETWEEN U.S. HIGHWAY 77 AND FM 892
            (TEXAS DEPARTMENT OF TRANSPORTATION. DRIVETEXAS.ORG)
            LATITUDE/LONGITUDE MARKS APPROXIMATE POSITION OF FM
            2826/U.S. HIGHWAY 77 INTERSECTION

0920 AM     FLASH FLOOD      FLOUR BLUFF             27.65N  97.30W
09/15/2018                   NUECES             TX   SOCIAL MEDIA

            REPORTS OF WATER ENTERING THE BOTTOM FLOOR OF SEVERAL
            APARTMENT BUILDINGS. THE TURNAROUND NEAR OSO BAY IS
            STARTING TO BECOME IMPASSABLE.

0920 AM     FLASH FLOOD      FLOUR BLUFF             27.65N  97.30W
09/15/2018                   NUECES             TX   PUBLIC

            HEAVY RAIN PRODUCING FLASH FLOODING WITH WATER MOVING
            INTO SOME APARTMENTS NEAR THE 9300 BLOCK OF SPID

0932 AM     FLASH FLOOD      FLOUR BLUFF             27.65N  97.30W
09/15/2018                   NUECES             TX   SOCIAL MEDIA

            MATLOCK STREET IN FLOUR BLUFF IS IMPASSABLE.

1000 AM     FLASH FLOOD      PORTLAND                27.88N  97.33W
09/15/2018                   SAN PATRICIO       TX   SOCIAL MEDIA

            PHOTOS AND VIDEOS OF SIGNIFICANT STREET FLOODING. WATER
            IS COVERING THE PARKING LOT OF AN AREA GAS STATION.

1026 AM     FLASH FLOOD      CLARKWOOD               27.78N  97.54W
09/15/2018                   NUECES             TX   LOCAL OFFICIAL

            CLARKWOOD ROAD AT HIGHWAY 44 IS FLOODED

1047 AM     FLASH FLOOD      TAFT                    27.98N  97.39W
09/15/2018                   SAN PATRICIO       TX   DEPT OF HIGHWAYS

            FM 631, FM 1944, AND FM 2046 ARE CLOSED DUE TO FLOODING
            VIA DRIVETEXAS.ORG

1144 AM     FLOOD            ROBSTOWN                27.80N  97.66W
09/15/2018                   NUECES             TX   SOCIAL MEDIA

            SEVERAL PICTURES AND VIDEOS OF STREET AND PARKING LOT
            FLOODING ROBSTOWN.

0152 PM     FLASH FLOOD      3 ESE FLOUR BLUFF       27.64N  97.25W
09/15/2018                   GMZ230             TX   PUBLIC

            ROADWAY UNDER JFK CAUSEWAY BRIDGE BECAME INUNDATED AND
            IMPASSABLE, EXCEPT FOR 1 LANE ON SOUTH SIDE OF BRIDGE,
            DURING PAST HOUR.

0214 PM     FLASH FLOOD      INGLESIDE ON THE BAY    27.84N  97.22W
09/15/2018                   SAN PATRICIO       TX   EMERGENCY MNGR

            IMPASSABLE ROADS DUE TO FLASH FLOODING FROM HEAVY RAIN
            NEAR THE WATERFRONT AT INGELSIDE ON THE BAY.

0235 PM     FLASH FLOOD      2 NW PORTLAND           27.90N  97.35W
09/15/2018                   SAN PATRICIO       TX   SOCIAL MEDIA

            FLASH FLOODING ON MEMORIAL PKWY AND LANG ROAD

0244 PM     FLASH FLOOD      4 NNW BAYSIDE           28.13N  97.27W
09/15/2018                   REFUGIO            TX   DEPT OF HIGHWAYS

            FM2511 4 NNW OF BAYSIDE CLOSED DUE TO FLASH FLOODING.

0245 PM     FLASH FLOOD      2 NE ODEM               27.97N  97.56W
09/15/2018                   SAN PATRICIO       TX   DEPT OF HIGHWAYS

            FM 1944 2 NE OF ODEM CLOSED DUE TO FLASH FLOODING.

0246 PM     FLASH FLOOD      4 NE ODEM               27.99N  97.54W
09/15/2018                   SAN PATRICIO       TX   DEPT OF HIGHWAYS

            FM 2046 4 NE OF ODEM CLOSED DUE TO FLASH FLOODING.

0339 PM     FLASH FLOOD      GREGORY                 27.92N  97.29W
09/15/2018                   SAN PATRICIO       TX   SOCIAL MEDIA

            FLASH FLOODING WITH STANDING WATER 1 TO 2 FEET DEEP

0433 PM     FLASH FLOOD      GREGORY                 27.92N  97.29W
09/15/2018                   SAN PATRICIO       TX   SOCIAL MEDIA

            VIDEO SHOWS SIGNIFICANT STANDING WATER...ABOUT 12 TO 18
            INCHES IN DEPTH...NEAR 3RD STREET

0523 PM     FLASH FLOOD      ROBSTOWN                27.80N  97.66W
09/15/2018                   NUECES             TX   SOCIAL MEDIA

            VIDEOS SHOWING SIGNIFICANT STREET FLOODING IN ROBSTOWN


&&

EVENT NUMBER CRP1800181 CRP1800182 CRP1800183 CRP1800185 CRP1800186
CRP1800188 CRP1800187 CRP1800189 CRP1800190 CRP1800191 CRP1800192
CRP1800194 CRP1800193 CRP1800197 CRP1800195 CRP1800196 CRP1800198
CRP1800199 CRP1800200 CRP1800205 CRP1800202 CRP1800203 CRP1800204
CRP1800206 CRP1800207 CRP1800208
Annaville - Photo Credit: Johnny Herrera Aransas County - Photo Credit: Jeremy Routh Flour Bluff - Photo Credit: Betsy Johnson Flour Bluff - Photo Credit: Matt Briscoe Ingleside On The Bay - Photo Credit: Sara Williams North Beach (Corpus Christi) - Photo Credit: KRIS TV 6 Portland - Photo Credit: Daniel Joskiewich Portland - Photo Credit: Michael Bryan Robstown - Photo Credit: Twitter @Medic30479 Robstown - Photo Credit: Twitter @Medic30479 Btwn Rockport and Aransas Pass - Photo Credit: Andrea Shetters Btwn Rockport and Aransas Pass - Photo Credit: Tammy Starr Rockport - Photo Credit: Meagan Preather Rockport - Photo Credit: Preston Adams Rockport - Photo Credit: Rachel Denny Clow - Corpus Christi Caller Times Rockport - Photo Credit: Rachel Denny Clow - Corpus Christi Caller Times Rockport - Photo Credit: Rachel Denny Clow - Corpus Christi Caller Times Rockport - Photo Credit: Rosemary Pizio Rockport - Photo Credit: Rosemary Pizio Rockport - Photo Credit: Rosemary Pizio Rockport - Photo Credit: Rosemary Pizio Rockport - Photo Credit: Rosemary Pizio Rockport - Photo Credit: Rosemary Pizio The Island (Corpus Christi)- Photo Credit: Mary Leal
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