Alert archive / Texas / Tornado Watches in 2009
Tornado Watch 165
The Storm Prediction Center issued this tornado watch at Apr 18, 2009, 9:53 AM CDT for 29 counties in Texas. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 18, 2009, 9:53 AM CDT (14:53 UTC)
- Expired
- Apr 18, 2009, 4:00 PM CDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1.5 in
- Strongest gust expected
- 60 kt
All 29 counties
Anderson County, TX, Angelina County, TX, Austin County, TX, Brazoria County, TX, Brazos County, TX, Burleson County, TX, Chambers County, TX, Cherokee County, TX, Colorado County, TX, Fort Bend County, TX, Freestone County, TX, Galveston County, TX, Grimes County, TX, Harris County, TX, Houston County, TX, Jackson County, TX, Leon County, TX, Liberty County, TX, Madison County, TX, Matagorda County, TX, Montgomery County, TX, Nacogdoches County, TX, Polk County, TX, San Jacinto County, TX, Trinity County, TX, Walker County, TX, Waller County, TX, Washington County, TX, Wharton County, TX
The radar
The Houston radar (KHGX), 139 km from the middle of the area, began a volume at 14:53 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 SPC expected
The probabilities SPC published with the watch, for the watch area over its life.
- Two or more tornadoes
- 50%
- One or more EF2 to EF5 tornadoes
- 20%
- Ten or more severe wind reports
- 20%
- One or more gusts of 65 knots or more
- 10%
- Ten or more severe hail reports
- 20%
- One or more hailstones of 2 inches or more
- 10%
- Six or more combined severe hail and wind reports
- 60%
Warnings issued inside it
17 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 18, 10:32 AM CDT | Tornado Warning | HGX | Washington | 28 min |
| Apr 18, 10:49 AM CDT | Tornado Warning | HGX | Grimes, Walker | 26 min |
| Apr 18, 11:40 AM CDT | Severe Thunderstorm Warning | HGX | Wharton | 50 min |
| Apr 18, 12:02 PM CDT | Severe Thunderstorm Warning | HGX | Brazoria, Fort Bend, Wharton | 43 min |
| Apr 18, 12:08 PM CDT | Tornado Warning | HGX | Brazoria, Fort Bend, Wharton | 37 min |
| Apr 18, 12:15 PM CDT | Severe Thunderstorm Warning | HGX | Liberty, Montgomery, San Jacinto | 45 min |
| Apr 18, 12:43 PM CDT | Severe Thunderstorm Warning | HGX | Brazoria, Fort Bend | 47 min |
| Apr 18, 12:46 PM CDT | Flash Flood Warning | HGX | Harris, Montgomery | 119 min |
| Apr 18, 1:22 PM CDT | Flash Flood Warning | HGX | Brazoria, Fort Bend, Galveston | 3 hr |
| Apr 18, 1:29 PM CDT | Severe Thunderstorm Warning | HGX | Brazoria, Fort Bend, Galveston, Harris | 46 min |
| Apr 18, 1:30 PM CDT | Severe Thunderstorm Warning | HGX | Fort Bend, Wharton | 45 min |
| Apr 18, 1:42 PM CDT | Flash Flood Warning | HGX | Chambers, Harris | 3 hr |
| Apr 18, 2:02 PM CDT | Flash Flood Warning | HGX | Austin, Colorado, Fort Bend, Wharton | 3 hr |
| Apr 18, 2:06 PM CDT | Severe Thunderstorm Warning | HGX | Brazoria, Galveston, Harris | 24 min |
| Apr 18, 3:05 PM CDT | Severe Thunderstorm Warning | HGX | Chambers, Galveston, Harris | 40 min |
| Apr 18, 3:33 PM CDT | Severe Thunderstorm Warning | HGX | Chambers | 42 min |
| Apr 18, 3:46 PM CDT | Tornado Warning | HGX | Brazoria, Galveston | 29 min |
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Lake Charles Mun, LA (KLCH), launched 12:00Z, 2.9 hours before the alert went out and 236 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
- 778 J/kg
- Mixed-layer CIN
- -108 J/kg
- Mixed-layer LCL
- 573 m above ground
- 0-6 km bulk shear
- 37 kt
- 0-1 km storm-relative helicity
- 160 m²/s²
- 0-3 km storm-relative helicity
- 499 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 8.3
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 17, 9:33 PM CDT | Mesoscale Discussion | SPC | Childress, Collingsworth, Cottle, Foard, Gray, Hansford and 13 more | 27 min |
| Apr 17, 11:44 PM CDT | Mesoscale Discussion | SPC | Atascosa, La Salle, McMullen | 61 min |
| Apr 18, 3:22 AM CDT | Mesoscale Discussion | SPC | Atascosa, Bandera, Bastrop, Bee, Bexar, Blanco and 34 more | 113 min |
| Apr 18, 4:21 AM CDT | Severe Thunderstorm Watch | SPC | Aransas, Atascosa, Austin, Bandera, Bastrop, Bee and 43 more | 7 hr |
| Apr 18, 6:32 AM CDT | Mesoscale Discussion | SPC | Atascosa, Bandera, Bastrop, Bexar, Caldwell, Comal and 17 more | 118 min |
| Apr 18, 9:47 AM CDT | Mesoscale Discussion | SPC | Anderson, Angelina, Austin, Brazoria, Brazos, Chambers and 22 more | 28 min |
| Apr 18, 10:52 AM CDT | Mesoscale Discussion | SPC | Aransas, Atascosa, Bee, Calhoun, DeWitt, Duval and 15 more | 53 min |
| Apr 18, 11:26 AM CDT | Mesoscale Discussion | SPC | Anderson, Angelina, Austin, Brazoria, Brazos, Burleson and 29 more | 2 hr |
| Apr 18, 1:01 PM CDT | Tornado Watch | SPC | Hardin, Jasper, Jefferson, Newton, Orange, Sabine and 3 more | 7 hr |
| Apr 18, 1:14 PM CDT | Mesoscale Discussion | SPC | Archer, Clay, Wichita | 61 min |
| Apr 18, 1:43 PM CDT | Mesoscale Discussion | SPC | Angelina, Austin, Brazoria, Chambers, Fort Bend, Galveston and 10 more | 92 min |
| Apr 18, 3:11 PM CDT | Severe Thunderstorm Watch | SPC | Archer, Clay, Collin, Cooke, Dallas, Denton and 14 more | 9 hr |
| Apr 18, 3:38 PM CDT | Mesoscale Discussion | SPC | Hardin, Jasper, Jefferson, Newton, Orange, Sabine and 3 more | 97 min |
| Apr 18, 5:14 PM CDT | Mesoscale Discussion | SPC | Cooke, Denton, Grayson | 91 min |
| Apr 18, 5:46 PM CDT | Mesoscale Discussion | SPC | Hardin, Jasper, Jefferson, Newton, Orange, Sabine and 3 more | 59 min |
Nearby
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.