A slow moving thunderstorm system developed across the Rio Grande Plains and South Texas Brush Country during the overnight and early morning hours. The slow moving convection became nearly stationary and backbuilt across Zapata County.
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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 BRO wrote it up.
A slow moving thunderstorm system developed across the Rio Grande Plains and South Texas Brush Country during the overnight and early morning hours. The slow moving convection became nearly stationary and backbuilt across Zapata County. An estimated five to eight inches of rain fell, resulting in flash flooding in and near the city of Zapata.
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 Brownsville, TX wrote its last area forecast discussion before the first event at Aug 21, 12:58 AM CST, 2 hours 32 minutes earlier.
Area Forecast Discussion...UPDATED National Weather Service BROWNSVILLE TX 158 AM CDT SUN AUG 21 2016 .DISCUSSION...Updated for latest aviation discussion below. && .AVIATION...Mid and High level cld cover associated with the convection firing to our north will move southwards over the RGV through the night and early morning hours. The convection to our north has not shown much progress pushing southwards. Daytime heating later today after sunrise may destabilize the atms enough to allow some isolated convection to form up across the RGV. Expect any convection that forms to likely miss the RGV airports during the afternoon. So will not include any vcts or tempo groups for convection later in the current TAF period. && .PREV DISCUSSION... /issued 649 PM CDT SAT AUG 20 2016/ DISCUSSION...Updated for latest aviation discussion below. AVIATION...VFR is anticipated through the next 24 hours. Winds will diminish tonight with a few clouds in place. Convection will likely develop over the western portion of Deep South Texas and the Rio Grande Valley but should remain away from all of the aerodromes. Tomorrow, breezy winds are expected with scattered clouds overhead. PREV DISCUSSION... /issued 248 PM CDT SAT AUG 20 2016/ SHORT TERM:(Now through Sunday Night): For some areas, a somewhat difficult forecast to close the weekend while others, as mentioned earlier today, should be able ride fairly easy based on persistence and analog cases. The main issue remains the 500 mb shear axis/weak trough that passes through central/south central texas and possibly leaves a "tail" behind it, with a lifting zone including the aforementioned area of concern of the far Upper Valley and Rio Grande Plains. The 12Z ECMWF came in a bit more robust on this system, and even brings a surface wind shift into the Rio Grande Plains ranchlands from a little after sunset Saturday through Sunday morning. Such a wind shift was a notable helper for the welcome but fairly "big" rains out there a week ago. The GFS is not as bullish but has the same configuration. And therein lies the good news: No matter which model or trend you choose, the dividing line between potential heavy rain, a little rain, and no rain is fairly clear. For the sensible weather, then: This afternoon shaping up just as expected: breezy, hot, and humid enough to push heat index in the 105-110 range for most areas east of U.S. 281. Current forecast covers this well,only introducing a mention of isolated thunderstorms across Zapata/western Starr toward sunset. This evening should play out with activation of thunderstorm clusters or even some type of band across Zapata. Exactly how much rain and whether training gets involved is a difficult question, as the ECMWF and the latest WPC QPF data suggest the possibility; later shifts will need to monitor potential for nuisance road flooding from Zapata to San Ygancio on US 83 and perhaps along SR 16 from Zapata to Hebbronville. Outflows should be able to kick out some of the convection farther east to include western Starr/Jim Hogg, probably between 9-10 PM and 1 AM, before fading away in the much deeper/drier air farther east and southeast, particularly the heavily populated RGV. Depicted a sharp cutoff from the higher chances to non-mentionable, which seems appropriate based on both ECMWF/GFS/NAM consensus and climatology with similar events. For Sunday, with deeper moisture remaining out west and north of the RGV as well as uncertainty with regard to where the shear axis lies (GFS wipes it out across the mid Valley and King Ranch while ECMWF keeps it across the lee of the Sierra Madre), maintained low end rain chances across the northern tier, shading back to isolated across the agricultural areas of Hidalgo/Willacy and basically little more than isolated light showers for all but Brownsville, mainly in the morning. With whatever MCS/energy to our north fading away during the afternoon, expect any mid/high clouds to thin over the Valley, and with a still decent southeast flow, temperatures should be able to rise well into the 90s for the Valley and could even touch 100 again in McAllen, but held just short with more clouds to begin the day. Farther north and west, temperatures may struggle into the low 90s - and the current forecast from Hebbronville to Zapata is an uncertain lower 90s; should light rain prevail into early afternoon there, mid to high 80s will be more likely. By Sunday night, both the GFS and ECMWF recede what's left of the shear axis back toward the Big Bend region as the upper ridge starts nosing back in from the east. Deeper dry air, particularly on the GFS over land, should kill off mentionable rain chances for all but the northern tier. Did add in some isolated streamer potential right at the coast (and Gulf) after midnight as layers from 700 to the surface temporarily fill with 60-80 percent RH. LONG TERM (Monday through Saturday):GFS/ECMWF are in very good agreement building the Bermuda Ridge west across the Gulf of Mexico the first half of next week. The center of the ridge works to its farthest point west, Louisiana, Wednesday before retreating east by the end of the week. Once the ridge begins to move east Gulf moisture will be on the increase with the chance of rain, albeit low, returning to the CWA. Atmospheric moisture begins to lower Monday with limited values to support convection. South winds may also be to strong and not in the most favored direction for sea breeze. Mean RH values drop to there lowest levels and PWATS falling well below seasonal averages Tuesday and Wednesday. Models are similar in retreating the ridge back to the east as broad upper trough tracks across the Northern Plains. Moisture begins its return but does not become deep or sufficient enough to support convection until Friday and Saturday. Winds become lighter and back more easterly favoring conditions for possible sea breeze activity gearing up for late next week. With the dry conditions through midweek temperatures are likely to be well above normal and will go above guidance. Then once the rain chances return temperatures to trend towards normal. MARINE:(Now through Sunday Night): Not a great day for fishing anywhere, as winds over the thinner Laguna Madre north of Mansfield are flirting with 20+ knots while the Bay between Port Isabel and SPI is running a few knots lower, in caution level but with choppy waters. The Gulf isn't much better; winds are fresh but tolerable while seas are dominated by wind waves vs. swell. At least it's sunny. For the overnight...continued southeast gradient will keep winds in caution levels over the Gulf while the Laguna will settle down, and while Sunday morning should be rain-free south of Mansfield, waves/chop will remain a nuisance issue especially for offshore excursions. By Sunday night, conditions should wind down some over the Gulf, making Monday morning fishing a better bet - though there will be a few dodge 'em showers in all waters by then. (Monday through Thursday)...the pressure gradient across the Western Gulf to strengthen through Wednesday as building high pressure over the Gulf combines with lower pressure over the Bay of Campeche and the Sierra Madre to produce a moderate south to southeast wind. Seas to builds also but winds and sea are not anticipated to reach small craft advisory levels but could at times attain marginal SCA levels. The gradient begins to weaken Thursday and into the weekend as the high pressure ridge moves east. HYDROLOGY...The big rains along the Rio Grande near Del Rio today, estimated between 6 and 8 inches (at least), are producing a flood "wave" that will reach Laredo and could produce minor flooding in some low lying unprotected locations along the river on Sunday. Why does this matter here? According to the Texas Water Development Board, the Texas share of reservoir capacity at Falcon had fallen to 32 percent recently - a clear response to our near record hot summer and "La Canicula" pattern. The flood "wave" will give a temporary boost to Falcon - nothing to get hopes too high, but at least put the lowering values in reverse (back up) next week to the tune of a few percentage points. && .BRO Watches/Warnings/Advisories... TX...None. GM...None. && This product is also available on the web at: HTTP://WEATHER.GOV/RGV Short Term...60 Long Term...69
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE BROWNSVILLE TX 438 PM CDT SAT AUG 20 2016 TXZ248>257-212100- ZAPATA-JIM HOGG-BROOKS-KENEDY-STARR-HIDALGO-INLAND WILLACY- INLAND CAMERON-COASTAL WILLACY-COASTAL CAMERON- 438 PM CDT SAT AUG 20 2016 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF DEEP SOUTH TEXAS. .DAY ONE...TONIGHT THERE IS A MODERATE RISK OF RIP CURRENTS AT THE BEACHES OF SOUTH PADRE ISLAND AND AT BOCA CHICA BEACH. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY AN ELEVATED RISK OF RIP CURRENTS IS POSSIBLE AT THE LOCAL BEACHES SUNDAY THROUGH WEDNESDAY. HEAT INDEX VALUES OF 103 TO 108 DEGREES ARE EXPECTED DURING THE AFTERNOON HOURS OF THE FORECAST PERIOD. .SPOTTER INFORMATION STATEMENT... SKYWARN SPOTTER ACTIVATION WILL NOT BE NEEDED. GMZ130-132-135-150-155-170-175-212100- LAGUNA MADRE FROM THE PORT OF BROWNSVILLE TO THE ARROYO COLORADO- LAGUNA MADRE FROM THE ARROYO COLORADO TO 5 NM NORTH OF PORT MANSFIELD TX- LAGUNA MADRE FROM 5 NM NORTH OF PORT MANSFIELD TO BAFFIN BAY TX- COASTAL WATERS FROM PORT MANSFIELD TO THE RIO GRANDE OUT 20 NM- COASTAL WATERS FROM BAFFIN BAY TO PORT MANSFIELD OUT 20 NM- WATERS FROM PORT MANSFIELD TO THE RIO GRANDE EXTENDING FROM 20 TO 60 NM- WATERS FROM BAFFIN BAY TO PORT MANSFIELD EXTENDING FROM 20 TO 60 NM- 438 PM CDT SAT AUG 20 2016 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF THE GULF OF MEXICO AND THE LAGUNA MADRE. .DAY ONE...TONIGHT NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY A SMALL CRAFT ADVISORY FOR WINDS IS POSSIBLE FOR THE LAGUNA MADRE ON WEDNESDAY. .SPOTTER INFORMATION STATEMENT... SKYWARN SPOTTER ACTIVATION WILL NOT BE NEEDED.
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1253 AM CDT SUN AUG 21 2016
TXZ248-249-210630-
ZAPATA TX-JIM HOGG TX-
1253 AM CDT SUN AUG 21 2016
...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN ZAPATA AND
NORTHWESTERN JIM HOGG COUNTIES UNTIL 130 AM CDT...
AT 1252 AM CDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM
NEAR THOMPSONVILLE...OR 12 MILES NORTHEAST OF BUSTAMANTE...MOVING
NORTHEAST AT 10 MPH.
DIME SIZE HAIL AND WINDS IN EXCESS OF 40 MPH WILL BE POSSIBLE WITH
THIS STORM.
LOCATIONS IMPACTED INCLUDE...
THOMPSONVILLE AND ESCOBAS.
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 2727 9887 2714 9874 2701 9906 2718 9912
2727 9900
TIME...MOT...LOC 0552Z 227DEG 9KT 2716 9899
69SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BROWNSVILLE TX
341 AM CDT SUN AUG 21 2016
TXZ248-210915-
ZAPATA TX-
341 AM CDT SUN AUG 21 2016
...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL ZAPATA COUNTY UNTIL 415
AM CDT...
AT 340 AM CDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM NEAR
ZAPATA HIGH SCHOOL...OR NEAR ZAPATA...MOVING SOUTHWEST AT 10 MPH.
NICKEL SIZE HAIL AND WINDS IN EXCESS OF 40 MPH WILL BE POSSIBLE WITH
THIS STORM.
LOCATIONS IMPACTED INCLUDE...
ZAPATA...BUSTAMANTE...MEDINA...ZAPATA MIDDLE SCHOOL...
ZAPATA HIGH SCHOOL...FALCON LAKE ESTATES...
ZAPATA COUNTY PUBLIC LIBRARY...FALCON SHORES...
ZAPATA COUNTY FIRE DEPARTMENT AND FALCON MESA.
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.
&&
LAT...LON 2691 9932 2702 9911 2692 9903 2676 9923
2677 9924 2679 9924 2682 9926 2684 9927
2685 9927 2686 9929 2687 9932 2688 9933
TIME...MOT...LOC 0840Z 054DEG 10KT 2691 9917
69The Corpus Christi radar (KCRP), 198 km away, was scanning. The volume nearest the first event began at 09:32 UTC.
1 lightning, 1 flash flood. Local standard time, as filed.
The Zapata County Emergency Manager also reported three lightning strikes to power poles in the Medina Addition, Siesta Shores, and in Falcon and a lightning strike to a gas tank in Aguilares.
The Zapata County Emergency Manager reported flash flooding across Zapata County with six known swift water rescues in and near the city of Zapata. At least two vehicles were submerged, one in fast flowing water and another with water up to the door handles. Standing water levels reached three feet on some roads, and creeks that exceeded their banks left between one and two feet of fast flowing water nearby. The Zapata County Sheriffs Office reported a foot and a half of water over Highway 83 in Zapata.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Texas in 2016Every state in 2016This day in weather historyWarnings in Texas, August 2016
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: 657942, 657937.