Alert archive / Texas / Flash Flood Warnings in 2021
Flash Flood Warning 1, NWS Houston/Galveston, TX
NWS Houston/Galveston, TX issued this flash flood warning at Apr 30, 2021, 6:01 AM CDT for 6 counties in Texas. It was in force for 5 hr. 2 reports came from inside the area while it was in force.
The area
The outline as issued, with what was reported inside it.
The facts
- Issued
- Apr 30, 2021, 6:01 AM CDT (11:01 UTC)
- Expired
- Apr 30, 2021, 11:00 AM CDT
- In force
- 5 hr
- Issued by
- NWS Houston/Galveston, TX
- Area
- Storm-based polygon
- Flood severity
- None
Counties Grimes County, TX, Harris County, TX, Montgomery County, TX, San Jacinto County, TX, Walker County, TX, Waller County, TX
The radar
The Houston radar (KHGX), 116 km from the middle of the area, began a volume at 11:03 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
What was reported inside it
| Time | Report | Where | Remark |
|---|---|---|---|
| Apr 30, 9:20 AM CDT | FLASH FLOOD | 7 Ese Huntsville, TX | WATER ON ROADWAY AT FM 2929/FM 2296 INTERSECTION. |
| Apr 30, 10:00 AM CDT | FLASH FLOOD | 1 Nnw Todd Mission, TX | WATER OVER ROADWAY AT FM 1774 NEAR COUNTY ROAD 302. REPORT FROM TXDOT. |
Local storm reports filed while the alert was in force, from inside its polygon or its counties.
The nearest sounding before it
Lake Charles Mun, LA (KLCH), launched 00:00Z, 11.0 hours before the alert went out and 243 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 1081 J/kg
- Mixed-layer CIN
- -32 J/kg
- Mixed-layer LCL
- 811 m above ground
- 0-6 km bulk shear
- 43 kt
- 0-1 km storm-relative helicity
- -21 m²/s²
- 0-3 km storm-relative helicity
- 22 m²/s²
- Significant tornado parameter
- 0.1
- Supercell composite
- 0.7
The text
As transmitted.
926
WGUS54 KHGX 301101
FFWHGX
TXC185-201-339-407-471-473-301400-
/O.NEW.KHGX.FF.W.0001.210430T1101Z-210430T1400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Houston/Galveston TX
601 AM CDT Fri Apr 30 2021
The National Weather Service in League City has issued a
* Flash Flood Warning for...
Southeastern Grimes County in southeastern Texas...
Harris County in southeastern Texas...
Northwestern Montgomery County in southeastern Texas...
West Central San Jacinto County in southeastern Texas...
Southeastern Walker County in southeastern Texas...
Northeastern Waller County in southeastern Texas...
* Until 900 AM CDT.
* At 601 AM CDT, Doppler radar and automated rain gauges indicated
thunderstorms producing heavy rain across the warned area. Between
2 and 5 inches of rain have fallen. Flash flooding is ongoing or
expected to begin shortly. The storms are expected to stall and
heavy rainfall is likely to continue. Roads may flood very quickly
with this intense rainfall.
HAZARD...Flash flooding caused by thunderstorms.
SOURCE...Doppler radar and automated gauges.
IMPACT...Flooding of small creeks and streams, urban areas,
highways, streets and underpasses as well as other
drainage and low lying areas.
* Some locations that will experience flash flooding include...
Northwestern Conroe, southeastern Huntsville, Willis, Prairie
View, Pinehurst, Waller, Panorama Village, Magnolia, New Waverly,
Pine Island, Montgomery, Todd Mission, Lake Conroe Dam, Huntsville
State Park, Dobbin, Dacus, Plantersville and Oakhurst.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
Be especially cautious at night when it is harder to recognize the
dangers of flooding.
Excessive runoff from heavy rainfall will cause flooding of small
creeks and streams, urban areas, highways, streets and underpasses
as well as other drainage areas and low lying spots.
&&
LAT...LON 3008 9604 3022 9600 3034 9595 3048 9579
3057 9570 3069 9555 3077 9532 3065 9526
3054 9527 3040 9543 3031 9561 3014 9581
3004 9593 3003 9605
FLASH FLOOD...RADAR AND GAUGE INDICATED
$$
kp1 follow-up statement
040
WGUS54 KHGX 301346
FFWHGX
TXC185-201-339-407-471-473-301600-
/O.EXT.KHGX.FF.W.0001.000000T0000Z-210430T1600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Houston/Galveston TX
846 AM CDT Fri Apr 30 2021
The National Weather Service in League City has extended the
* Flash Flood Warning for...
Southeastern Grimes County in southeastern Texas...
Harris County in southeastern Texas...
Northwestern Montgomery County in southeastern Texas...
West Central San Jacinto County in southeastern Texas...
Southeastern Walker County in southeastern Texas...
Northeastern Waller County in southeastern Texas...
* Until 1100 AM CDT.
* At 846 AM CDT, Doppler radar and automated rain gauges indicated
thunderstorms producing heavy rain across the warned area. Between
4 and 7 inches of rain have fallen. Flash flooding is already
occurring.
HAZARD...Flash flooding caused by thunderstorms.
SOURCE...Doppler radar and automated gauges.
IMPACT...Flooding of small creeks and streams, urban areas,
highways, streets and underpasses as well as other
drainage and low lying areas.
* Some locations that will experience flash flooding include...
Northwestern Conroe, southeastern Huntsville, Willis, Prairie
View, Pinehurst, Waller, Panorama Village, Magnolia, New Waverly,
Pine Island, Montgomery, Todd Mission, Lake Conroe Dam, Huntsville
State Park, Dobbin, Dacus, Plantersville and Oakhurst.
Additional rainfall amounts of 1 to 2 inches are possible in the
warned area.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
Excessive runoff from heavy rainfall will cause flooding of small
creeks and streams, country roads, farmland, and other low lying
spots.
Please report flooding to your local law enforcement agency when you
can do so safely.
A Flash Flood Warning means that flooding is imminent or occurring.
If you are in the warned area move to higher ground immediately.
Residents living along streams and creeks should take immediate
precautions to protect life and property.
&&
LAT...LON 3008 9604 3022 9600 3034 9595 3048 9579
3057 9570 3069 9555 3077 9532 3065 9526
3054 9527 3040 9543 3031 9561 3014 9581
3004 9593 3003 9605
FLASH FLOOD...RADAR AND GAUGE INDICATED
$$The office that day
Everything else NWS Houston/Galveston, TX issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 29, 9:33 PM CDT | Flash Flood Watch | HGX | Austin, Brazoria, Brazos, Burleson, Chambers, Colorado and 17 more | 55 hr |
| Apr 30, 3:17 AM CDT | Areal Flood Advisory | HGX | Houston, Madison, Trinity, Walker | 3 hr |
| Apr 30, 3:38 AM CDT | Coastal Flood Advisory | HGX | Brazoria, Galveston, Matagorda | 15 hr |
| Apr 30, 3:38 AM CDT | Rip Current Statement | HGX | Brazoria, Galveston, Matagorda | 15 hr |
| Apr 30, 3:49 AM CDT | Small Craft Advisory | HGX | 17 hr | |
| Apr 30, 4:05 AM CDT | Special Weather Statement | HGX | Matagorda | 40 min |
| Apr 30, 5:06 AM CDT | Special Weather Statement | HGX | Liberty, Polk, San Jacinto | 39 min |
| Apr 30, 5:08 AM CDT | Special Weather Statement | HGX | Colorado, Wharton | 52 min |
| Apr 30, 5:40 AM CDT | Areal Flood Advisory | HGX | Austin, Grimes, Harris, Montgomery, Waller, Washington | 3 hr |
| Apr 30, 7:05 AM CDT | Areal Flood Advisory | HGX | Liberty, Montgomery, Polk, San Jacinto | 3 hr |
| Apr 30, 8:19 AM CDT | Areal Flood Advisory | HGX | Chambers, Harris, Liberty, Montgomery | 116 min |
| Apr 30, 9:12 AM CDT | Areal Flood Advisory | HGX | Harris, Liberty, Montgomery, Polk, San Jacinto | 2 hr |
| Apr 30, 9:53 AM CDT | Areal Flood Advisory | HGX | Austin, Harris, Waller, Washington | 112 min |
| Apr 30, 11:04 AM CDT | Areal Flood Advisory | HGX | Austin, Brazos, Burleson, Grimes, Harris, Houston and 9 more | 116 min |
Nearby
Flash Flood Warnings in Texas, 2021Every flash flood warning in 2021
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.