Tornadoes · United States · Texas · 2009
EF1 tornado, Weir to Jonah, Texas, April 27, 2009
From Weir to Jonah, this EF1 tornado ran 2.1 miles across Williamson County on April 27, 2009, touching down at 4:10 AM CDT and reaching 50 yards wide. It killed nobody, and did $1.0 million of property damage.
The rating scale
Tracks are drawn in the color of the rating. The Enhanced Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.
EF065 to 85 mph
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
EF186 to 110 mphthis tornado
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
EF2111 to 135 mph
Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.
EF3136 to 165 mph
Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.
EF4166 to 200 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
EF5over 200 mph
Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.
Unrated
The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.
The record
- Rating
- EF1
- Date
- April 27, 2009
- Touchdown
- 4:10 AM CDT (09:10 UTC)
- Lifted
- 4:15 AM CDT (09:15 UTC)
- On the ground
- 5 minutes
- Path length
- 2.1 miles (3.4 km)
- Path width
- 50 yards (46 m)
- Deaths
- 0
- Injuries
- 0
- Property damage
- $1.0 million
- County
- Williamson County
- Touchdown point
- 30.627, -97.588
- Lift-off point
- 30.639, -97.558
- Record number
- 0904270310-01
What the Weather Service recorded
A cold front combined with warm, moist southerly surface flow caused severe thunderstorms in South Central Texas.
A NWS storm survey concluded an EF1 tornado with winds estimated at 85 to 95 mph developed three miles WSW of Jonah, moved northeast and dissipated one mile west of Jonah along Hwy 29. Over 20 homes were damaged, mostly minor roof damage due to falling branches and trees. Several out buildings and small storage sheds were destroyed. Three power poles were snapped. One travel trailer was rolled on its side.
From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.
The warnings
No tornado warning for this county appears in the archive as in force at the moment the tornado touched down. One was issued for the county at another hour that day.
| Issued (UTC) | Expired | Product | Office |
|---|---|---|---|
| 08:20 UTC | 10:15 UTC | Flood Advisory | EWX |
| 09:28 UTC | 10:00 UTC | Tornado Warning | EWX |
| 09:48 UTC | 10:15 UTC | Tornado Warning | EWX |
| 11:11 UTC | 18:00 UTC | Tornado Watch | EWX |
| 13:00 UTC | 12:19 UTC | Flood Watch | EWX |
| 13:00 UTC | 21:00 UTC | Flash Flood Watch | EWX |
| 16:58 UTC | 19:00 UTC | Flood Advisory | EWX |
| 18:07 UTC | 20:30 UTC | Flash Flood Warning | EWX |
Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.
The forecast that day
The Storm Prediction Center had this point in a Slight Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 06:00 UTC.
SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.
The air that afternoon
The radiosonde launches on either side of the tornado, from the nearest station that was launching then, drawn and analyzed the way Storm Lab does: the same diagram, the same parcel and shear definitions SPC's mesoanalysis uses.
Fort Worth, TX (KFWD), 00:00Z
9.2 hours before the tornado, 246 km from the path. April 27, 2009.
- Mixed-layer CAPE
- 479 J/kg
- Mixed-layer CIN
- -125 J/kg
- Surface CAPE
- 759 J/kg
- Mixed-layer LCL
- 1254 m above ground
- 0-6 km bulk shear
- 48 kt
- 0-1 km bulk shear
- 33 kt
- 0-1 km storm-relative helicity
- 228 m²/s²
- 0-3 km storm-relative helicity
- 360 m²/s²
- Significant tornado parameter
- 0.3
- Supercell composite
- 3.3
- 0-3 km lapse rate
- 6.7 K/km
Fort Worth, TX (KFWD), 12:00Z
2.8 hours after it, 246 km from the path. April 27, 2009.
- Mixed-layer CAPE
- 2160 J/kg
- Mixed-layer CIN
- 0 J/kg
- Surface CAPE
- 2199 J/kg
- Mixed-layer LCL
- 513 m above ground
- 0-6 km bulk shear
- 20 kt
- 0-1 km bulk shear
- 26 kt
- 0-1 km storm-relative helicity
- 79 m²/s²
- 0-3 km storm-relative helicity
- 315 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 6.5
- 0-3 km lapse rate
- 6.2 K/km
The radar
The Ft Hood radar (KGRK), 21 km away, was scanning. The volume nearest the touchdown began at 09:09 UTC.
Open the radar archive at this moment, over the track
Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.
What was reported nearby
Local storm reports within 60 km of the path, in the three hours either side.
| Time (UTC) | Report | Where | County | Remark |
|---|---|---|---|---|
| 09:15 UTC | TSTM WND DMG | 8 Ese Georgetown | Williamson, TX | POWER LINES SNAPPED, TREES DOWN, SEVERE DAMAGE TO A PORCH |
| 09:15 UTC | HAIL 0.25 | 8 Ese Georgetown | Williamson, TX | PEA SIZE HAIL AND GUSTY WINDS |
| 09:15 UTC | TORNADO | 3 S Weir | Williamson, TX | NWS DAMAGE SURVEY CONCLUDED AN EF1 TORNADO WITH WINDS ESTIMATED 85 TO 95 MPH DEVELOPED 3 MILES WSW OF JONAH...MOVED NORTHEAST AND DISSIPATED 1 MILE WEST OF JONAH ALONG HIGHWAY 29. THE TORNADO HAD A PATH OF 2 MILES AND WA |
| 09:19 UTC | TSTM WND DMG | 9 E Georgetown | Williamson, TX | BETWEEN 12 TO 15 HOMES DAMAGE JUST WEST OF JONAH. DAMAGE IS MAINLY DUE TO WINDS AND TREES BEING BLOWN ONTO HOMES. |
| 10:10 UTC | TSTM WND GST 70 | Holland | Bell, TX | 70 MPH WIND GUST IN HOLLAND. ESTIMATED BY A STORM SPOTTER |
From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.
This ground now
The live radar over the trackEvery 2009 tornado in TexasEvery tornado in Texas since 1950Warnings in force in Texas nowThe forecast where you are
The other tornadoes of April 27, 2009
6 more were confirmed in the United States that day.
| Date | Time | Rating | Where | Path (mi) | Width (yd) | Deaths | Injuries | Damage |
|---|---|---|---|---|---|---|---|---|
| April 27 | 8:30 AM CDT | EF1 | Navarro, TX | 0.6 | 67 | 1 | $100,000 | |
| April 27 | 9:28 AM CDT | EF0 | Van Zandt, TX | 0.8 | 20 | |||
| April 27 | 3:36 PM CDT | EF0 | DeWitt, TX | 0.1 | 10 | $50,000 | ||
| April 27 | 6:11 PM CDT | EF1 | Johnson, AR | 3.1 | 180 | $50,000 | ||
| April 27 | 9:25 PM CDT | EF0 | Newton, TX | 0.0 | 10 | $1,000 | ||
| April 27 | 9:29 PM CDT | EF0 | Jasper, TX | 0.0 | 10 |
What this means
Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.
Sources
NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.