A cold front moved into a very moist environment where precipitable water values were near and above two inches. Thunderstorms developed and some produced heavy rain that led to flash flooding.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS EWX wrote it up.
A cold front moved into a very moist environment where precipitable water values were near and above two inches. Thunderstorms developed and some produced heavy rain that led to flash flooding.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Austin/San Antonio, TX wrote its last area forecast discussion before the first event at Sep 21, 11:48 PM CST, 25 minutes earlier.
Area Forecast Discussion National Weather Service Austin/San Antonio TX 1248 AM CDT Sat Sep 22 2018 .AVIATION... Convection to the west of SAT/SSF/AUS will be impacting the airports over the next several hours. Looks like DRT has likely seen the worse of it and will keep the NW wind through the period. Have a mention of VCSH for DRT first half of the forecast but shouldn't see much additional strong convection according to the mesoscale models. The slow moving front will keep the convection along I-35 over the next several hours. The HRRR and TTWRF show the line of convection to be mainly east of AUS/SAT/SSF by late morning. Have dropped the tempo groups of TS and kept VCSH through the early afternoon Saturday with wrap around moisture. MVFR decks should hold strong most if not all day. Don't look for much improvement except maybe at DRT late in the day when they might scatter out. Humidity cross sections through the area have it socked in with very high RH despite the northerly winds. && .PREV DISCUSSION... /ISSUED 938 PM CDT Fri Sep 21 2018/ UPDATE... Scattered showers and thunderstorms will continue overnight as a cold front moves into our CWA. The extent of the convection has been less than we previously forecast and we have lowered the POPs over the northern and western parts of the area. The front is currently approaching Val Verde County from the northwest. It should continue to move to the southeast through the night and produce showers and thunderstorms. The 00Z sounding from the DRT showed 1.92" PW, so there is still excessive moisture in the atmosphere. Locally heavy rain is possible and some this could lead to flash flooding. The Flash Flood Watch will continue into Saturday. PREV DISCUSSION... /ISSUED 649 PM CDT Fri Sep 21 2018/ AVIATION... Timing of convection will be tough the next 24 hours. Until frontal convection develops closer to the predawn hours, VCSH will be listed in many of the time periods as a very moist atmosphere will allow for some pop up convection after the sun goes down and the low level jet strengthens. Cluster of storms out by DRT has weakened with several outflows in that region. Another cluster of storms to the east of AUS is pushing an outflow westward and may be a trigger for later convection this evening. Will keep the NW wind out in DRT for the duration of the TAF forecast...I-35 sites getting the wind shift likely late morning. Prior to that, have a prevailing group of showers predawn through late morning at AUS/SAT/SSF. No mention of TS right now, but later shifts will likely have to add in for some smaller time period. Cloud decks to should lower to MVFR all areas after midnight...likely sooner at SAT/SSF. Not out of the question that we could touch IFR before convection hits in the early morning. PREV DISCUSSION... /ISSUED 314 PM CDT Fri Sep 21 2018/ SHORT TERM (Tonight through Sunday)... Late afternoon surface observations show a cold front located across the lower Trans Pecos region of west Texas, with plenty of moist, southerly flow in place across south central Texas. The 21/12Z upper air observations also show very high moisture in place with precipitable water values around 2.2" at both CRP and DRT. We are beginning to see some clearing as of late this afternoon across portions of Val Verde county. As the above mentioned cold front moves southward, we expect a line of showers and storms to develop across the southern Edwards Plateau and Rio Grande plains late this afternoon and evening. This line of convection is then expected to move eastward through the remainder of this evening into the overnight hours. Given good agreement among the hi-res models in showing a line of convection moving southward overnight, we will issue a Flash Flood Watch for portions of the Rio Grande plains, southern Edwards Plateau and Hill Country. This will include counties along and north of a Del Rio to Hondo to Burnet line. We contemplated adding Maverick county into the watch, as the models do show a weak signal for some heavier amounts this far south along the Rio Grande. However, our confidence is a little low as of now and we will leave Maverick county out of the Watch. With deep moisture, efficient precipitation producing processes (tall, skinny CAPEs) and possible training of cells along the front and wet ground, some flash flooding is certainly possible. For now, the watch area will not cover the I-35 corridor. However, we still can't rule out some pockets of heavy rainfall late tonight into Saturday morning along the I-35 corridor. We will continue to monitor radar trends and model data and adjust the Flash Flood Watch as necessary. For late Saturday afternoon into Saturday evening, the cold front should slide east and focus the better rain chances into areas east of the I-35 corridor. Deep moisture will remain in place and with frontal lift, we will continue to show a very good chance for rainfall. On Sunday, the coastal plains and Highway 77 corridor will continue to be favored for additional rainfall, with lesser chances westward across the I-35 corridor and Hill Country. As for expected rainfall amounts, the models have trended a little lower along the I-35 corridor and a little higher across the southern Edwards Plateau. For this event (tonight through Sunday), we will forecast widespread 1-3 inches, with isolated higher amounts of 5 to 6 inches. The focus for the higher totals is expected to remain in the Flash Flood Watch Area. LONG TERM (Sunday night through Friday)... For Sunday night, the better rain chances will be located across the coastal plains and Highway 77 corridor. Farther west, it appears some drier air moving in from the west will greatly limit rainfall chances. On Monday, the cold front will weaken as return southerly flow spreads back across all of south central Texas. Rain chances will again be favored across the coastal plains and Highway 77 corridor where deeper moisture will be found. For the middle portion of the upcoming work week, a broad upper trough will linger over the central and southern U.S. plains. A cold front tries to make some southward progress into central Texas on Wednesday, but may very well slow down and not move through or stall over the region. Given a potential slow-moving or stalled front, the weak upper trough and plenty of moisture, we will keep rain chances in the forecast through the middle and later portion of the upcoming work week. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 69 84 71 87 74 / 30 30 20 20 10 Austin Bergstrom Intl Airport 69 84 70 87 74 / 40 30 20 20 10 New Braunfels Muni Airport 69 85 70 88 73 / 30 20 10 20 10 Burnet Muni Airport 66 80 68 85 71 / 20 30 20 20 10 Del Rio Intl Airport 68 84 68 88 72 / 10 10 - - - Georgetown Muni Airport 68 82 69 86 73 / 40 30 20 20 10 Hondo Muni Airport 68 83 69 88 72 / 20 20 10 10 10 San Marcos Muni Airport 68 85 70 88 73 / 40 20 20 20 10 La Grange - Fayette Regional 72 86 72 88 74 / 60 40 30 40 20 San Antonio Intl Airport 68 84 71 88 73 / 30 20 10 10 10 Stinson Muni Airport 70 85 72 88 74 / 30 20 10 10 10 && .EWX WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch through this afternoon for Bandera-Blanco-Burnet- Edwards-Gillespie-Kendall-Kerr-Kinney-Llano-Medina-Real-Uvalde-Val Verde. && Mesoscale/Aviation...09 Synoptic/Grids...04
Hazardous Weather Outlook National Weather Service Austin/San Antonio TX 441 AM CDT Fri Sep 21 2018 TXZ171>173-183>194-202>209-217>225-228-221000- Llano-Burnet-Williamson-Val Verde-Edwards-Real-Kerr-Bandera- Gillespie-Kendall-Blanco-Hays-Travis-Bastrop-Lee-Kinney-Uvalde- Medina-Bexar-Comal-Guadalupe-Caldwell-Fayette-Maverick-Zavala- Frio-Atascosa-Wilson-Karnes-Gonzales-De Witt-Lavaca-Dimmit- 441 AM CDT Fri Sep 21 2018 This Hazardous Weather Outlook is for South-Central Texas.. .DAY ONE...Today And Tonight. Isolated to scattered showers and thunderstorms are possible today. More numerous showers and storms are expect to develop tonight across portions of the Hill Country and Rio Grande. Pockets of locally heavy rainfall tonight across this region could lead to flooding issues. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. The threat for numerous showers and storms will shift eastward on Saturday. Pockets of locally heavy rainfall could lead to minor flooding issues across the southern and eastern Hill Country, and along and east of the I-35 corridor on Saturday. .SPOTTER INFORMATION STATEMENT... While spotter activation is not anticipated, any reports of heavy rainfall or flooding are appreciated.
Special Weather Statement
National Weather Service Austin/San Antonio TX
939 PM CDT FRI SEP 21 2018
TXZ194-220330-
Lee TX-
939 PM CDT FRI SEP 21 2018
...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN LEE COUNTY UNTIL
1030 PM CDT...
At 938 PM CDT, Doppler radar was tracking a strong thunderstorm over
Dime Box, or 12 miles east of Lexington, moving north at 10 mph.
Winds in excess of 40 mph will be possible with this storm. Some
small hail is also possible with this storm.
Locations impacted include...
Dime Box, Lake Somerville State Park & Trailway, Old Dime Box and
Loebau.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
&&
LAT...LON 3029 9669 3025 9689 3049 9693 3049 9690
3048 9691 3046 9690 3046 9688 3043 9687
3043 9685 3039 9679 3032 9674 3032 9669
TIME...MOT...LOC 0238Z 194DEG 8KT 3035 9681
YURASpecial Weather Statement
National Weather Service Austin/San Antonio TX
1124 PM CDT FRI SEP 21 2018
TXZ173-220515-
Williamson TX-
1124 PM CDT FRI SEP 21 2018
...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN WILLIAMSON COUNTY
UNTIL 1215 AM CDT...
At 1124 PM CDT, Doppler radar was tracking a strong thunderstorm over
Coupland, or 7 miles north of Elgin, moving east at 10 mph.
Winds in excess of 40 mph will be possible with this storm.
Locations impacted include...
Taylor, Thrall, Coupland, Beyarsville, Rices Crossing and Noack.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
&&
LAT...LON 3046 9716 3040 9733 3042 9736 3042 9738
3044 9740 3044 9742 3046 9744 3046 9746
3048 9750 3052 9751 3061 9722
TIME...MOT...LOC 0424Z 258DEG 9KT 3045 9741
RUNYENThe Austin/San Antonio radar (KEWX), 101 km away, was scanning. The volume nearest the first event began at 06:11 UTC.
11 flash flood, 1 flood. Local standard time, as filed.
Thunderstorms produced heavy rain that led to flash flooding. Parts of Hwy 16 and Hwy 173 were closed near Bandera due to water over the road.
Thunderstorms produced heavy rain that led to flash flooding closing several roads in and around Coupland.
Thunderstorms produced heavy rain that led to flash flooding closing several roads in and around Taylor.
Thunderstorms produced heavy rain that led to flash flooding. Several low water crossings on CR 330 were flooded along the South Fork of the San Gabriel River southwest of Bertram.
More than sixty people had to be rescued from the Casa Rio Del Colores wedding venue as a large wedding party got trapped from quickly rising waters along the South Fork of the San Gabriel River just south of Liberty Hill. Multiple cars were flooded and inundated.
Thunderstorms produced heavy rain that led to flash flooding. Park Rd. 37 was closed due to high water in a few locations northeast of Lakehills.
Thunderstorms produced heavy rain that led to flash flooding closing multiple roads in the northwestern part of Bexar County.
Thunderstorms produced heavy rain that led to flash flooding closing several county roads in the southern half of the county.
Williamson County officials reported multiple flooded roads across the eastern sections of Williamson County especially around and just south of Taylor.
Thunderstorms produced heavy rain that led to flash flooding closing several low water crossings across the north central and northwestern part of the county.
Williamson County officials reported multiple roads closed due to flooding across the eastern half of the county.
There were several RVs that were flooded along the Medina River in the Medina River RV Park as the water rose after a night and morning of heavy rain upstream. Over 20 people were rescued from their RVs as they became trapped when the river rose above banks and flooded the RV park.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Texas in 2018Every state in 2018This day in weather historyWarnings in Texas, September 2018
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 784145, 784147, 784148, 784150, 786656, 784151, 784152, 784153, 786657, 784154, 786659, 786643.