Alert archive / Texas / Severe Thunderstorm Warnings in 2021
Severe Thunderstorm Warning 91, NWS Houston/Galveston, TX
NWS Houston/Galveston, TX issued this severe thunderstorm warning at Dec 18, 2021, 10:39 AM CST for Harris County, Montgomery County, Texas. It was in force for 20 min. 1 report 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
- Dec 18, 2021, 10:39 AM CST (16:39 UTC)
- Expired
- Dec 18, 2021, 10:59 AM CST
- In force
- 20 min
- Issued by
- NWS Houston/Galveston, TX
- Area
- Storm-based polygon
- Tornado
- Possible
- Hail
- 0.75 in
- Wind
- 60.0 mph
Counties Harris County, TX, Montgomery County, TX
The radar
The Houston radar (KHGX), 103 km from the middle of the area, began a volume at 16:40 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 |
|---|---|---|---|
| Dec 18, 10:40 AM CST | TSTM WND DMG | 6 Nnw The Woodlands, TX | CORRECTS PREVIOUS TSTM WND DMG REPORT FROM 6 NNW THE WOODLANDS. TREES DOWN, MONTGOMERY DRIVE. ADJUSTED TIME BASED ON RADAR. |
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 12:00Z, 4.7 hours before the alert went out and 227 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
- 1750 J/kg
- Mixed-layer CIN
- -4 J/kg
- Mixed-layer LCL
- 441 m above ground
- 0-6 km bulk shear
- 37 kt
- 0-1 km storm-relative helicity
- 120 m²/s²
- 0-3 km storm-relative helicity
- 127 m²/s²
- Significant tornado parameter
- 0.9
- Supercell composite
- 5.7
The text
As transmitted.
902 WUUS54 KHGX 181639 SVRHGX TXC201-339-181715- /O.NEW.KHGX.SV.W.0091.211218T1639Z-211218T1715Z/ BULLETIN - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Warning National Weather Service Houston/Galveston TX 1039 AM CST Sat Dec 18 2021 The National Weather Service in League City has issued a * Severe Thunderstorm Warning for... Western Montgomery County in southeastern Texas... North central Harris County in southeastern Texas... * Until 1115 AM CST. * At 1038 AM CST, severe thunderstorms were located along a line extending from 6 miles north of Lake Conroe Dam to near Montgomery, moving southeast at 30 mph. HAZARD...60 mph wind gusts. SOURCE...Radar indicated. IMPACT...Expect damage to roofs, siding, and trees. * Locations impacted include... Conroe, Tomball, The Woodlands, Panorama Village, Montgomery and Lake Conroe Dam. PRECAUTIONARY/PREPAREDNESS ACTIONS... For your protection move to an interior room on the lowest floor of a building. && LAT...LON 3032 9543 3005 9557 3032 9574 3051 9561 TIME...MOT...LOC 1638Z 331DEG 28KT 3045 9560 3033 9566 TORNADO...POSSIBLE HAIL THREAT...RADAR INDICATED MAX HAIL SIZE...<.75 IN WIND THREAT...RADAR INDICATED MAX WIND GUST...60 MPH $$
1 follow-up statement
937
WWUS54 KHGX 181659
SVSHGX
Severe Weather Statement
National Weather Service Houston/Galveston TX
1059 AM CST Sat Dec 18 2021
TXC201-339-181708-
/O.CAN.KHGX.SV.W.0091.000000T0000Z-211218T1715Z/
Montgomery TX-Harris TX-
1059 AM CST Sat Dec 18 2021
...THE SEVERE THUNDERSTORM WARNING FOR WESTERN MONTGOMERY AND NORTH
CENTRAL HARRIS COUNTIES IS CANCELLED...
The storms which prompted the warning have moved out of the area.
Therefore, the warning has been cancelled. A new severe thunderstorm
warning has been issued to cover the new threatened area. See the
bulletin for that warning for more details.
LAT...LON 3032 9543 3005 9557 3032 9574 3051 9561
TIME...MOT...LOC 1657Z 331DEG 28KT 3032 9552 3020 9558
$$The office that day
Everything else NWS Houston/Galveston, TX issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 17, 10:46 PM CST | Marine Dense Fog Advisory | HGX | 11 hr | |
| Dec 18, 3:33 AM CST | Gale Watch | HGX | 11 hr | |
| Dec 18, 3:33 AM CST | Gale Warning | HGX | 24 hr | |
| Dec 18, 5:56 AM CST | Dense Fog Advisory | HGX | Galveston | 4 hr |
| Dec 18, 8:48 AM CST | Special Weather Statement | HGX | Houston | 57 min |
| Dec 18, 8:58 AM CST | Special Weather Statement | HGX | Brazos, Burleson | 47 min |
| Dec 18, 9:28 AM CST | Special Weather Statement | HGX | Grimes, Washington | 47 min |
| Dec 18, 9:43 AM CST | Special Weather Statement | HGX | Trinity, Walker | 62 min |
| Dec 18, 9:54 AM CST | Special Weather Statement | HGX | Montgomery | 51 min |
| Dec 18, 10:09 AM CST | Special Weather Statement | HGX | Montgomery, Waller | 66 min |
| Dec 18, 10:21 AM CST | Severe Thunderstorm Warning | HGX | Grimes, Montgomery, Walker | 24 min |
| Dec 18, 10:52 AM CST | Tornado Warning | HGX | Montgomery, San Jacinto | 23 min |
| Dec 18, 10:57 AM CST | Severe Thunderstorm Warning | HGX | Harris, Liberty, Montgomery, San Jacinto | 33 min |
| Dec 18, 11:15 AM CST | Areal Flood Advisory | HGX | Montgomery, San Jacinto, Walker | 2 hr |
| Dec 18, 11:25 AM CST | Special Weather Statement | HGX | Brazoria, Chambers, Fort Bend, Harris, Jackson, Liberty and 5 more | 65 min |
| Dec 18, 11:29 AM CST | Severe Thunderstorm Warning | HGX | Harris, Liberty, Montgomery, San Jacinto | 31 min |
| Dec 18, 11:41 AM CST | Severe Thunderstorm Warning | HGX | Harris | 34 min |
| Dec 18, 11:53 AM CST | Special Marine Warning | HGX | 2 hr | |
| Dec 18, 12:09 PM CST | Areal Flood Advisory | HGX | Harris | 111 min |
| Dec 18, 12:36 PM CST | Special Weather Statement | HGX | Brazoria, Chambers, Galveston, Matagorda | 54 min |
| Dec 18, 1:18 PM CST | Areal Flood Advisory | HGX | Brazoria, Chambers, Galveston, Harris | 117 min |
| Dec 18, 1:31 PM CST | Special Weather Statement | HGX | Brazoria, Galveston, Matagorda | 59 min |
| Dec 18, 1:55 PM CST | Special Marine Warning | HGX | 2 hr | |
| Dec 18, 2:17 PM CST | Small Craft Advisory | HGX | 44 hr | |
| Dec 18, 3:52 PM CST | Special Marine Warning | HGX | 53 min |
Nearby
Severe Thunderstorm Warnings in Texas, 2021Every severe thunderstorm 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.