Alert archive / Texas / Tornado Warnings in 2021

Tornado Warning 31, NWS Houston/Galveston, TX

December 18, 2021Montgomery County, San Jacinto County, Texas

NWS Houston/Galveston, TX issued this tornado warning at Dec 18, 2021, 10:52 AM CST for Montgomery County, San Jacinto County, Texas. It was in force for 23 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Dec 18, 2021, 10:52 AM CST (16:52 UTC)
Expired: Dec 18, 2021, 11:15 AM CST
In force: 23 min
Issued by: NWS Houston/Galveston, TX
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 0.75 in

Counties Montgomery County, TX, San Jacinto County, TX

The radar

The Houston radar (KHGX), 108 km from the middle of the area, began a volume at 16:52 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.

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 12:00Z, 4.9 hours before the alert went out and 198 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

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

Open this sounding in Storm Lab

The text

As transmitted.

647 
WFUS54 KHGX 181652
TORHGX
TXC339-407-181715-
/O.NEW.KHGX.TO.W.0031.211218T1652Z-211218T1715Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Houston/Galveston TX
1052 AM CST Sat Dec 18 2021

The National Weather Service in League City has issued a

* Tornado Warning for...
  Northeastern Montgomery County in southeastern Texas...
  Southwestern San Jacinto County in southeastern Texas...

* Until 1115 AM CST.
    
* At 1052 AM CST, a severe thunderstorm capable of producing a
  tornado was located near Cut And Shoot, or 12 miles west of
  Cleveland, moving northeast at 20 mph.

  HAZARD...Tornado.

  SOURCE...Radar indicated rotation.

  IMPACT...Flying debris will be dangerous to those caught without 
           shelter. Mobile homes will be damaged or destroyed. 
           Damage to roofs, windows, and vehicles will occur.  Tree 
           damage is likely.

* This tornadic thunderstorm will remain over mainly rural areas of
  northeastern Montgomery and southwestern San Jacinto Counties.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 3037 9531 3040 9532 3060 9516 3042 9505
TIME...MOT...LOC 1652Z 241DEG 18KT 3040 9527 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...<.75 IN

$$

2 follow-up statements

364 
WWUS54 KHGX 181700
SVSHGX

Severe Weather Statement
National Weather Service Houston/Galveston TX
1100 AM CST Sat Dec 18 2021

TXC339-407-181715-
/O.CON.KHGX.TO.W.0031.000000T0000Z-211218T1715Z/
Montgomery TX-San Jacinto TX-
1100 AM CST Sat Dec 18 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 1115 AM CST FOR
NORTHEASTERN MONTGOMERY AND SOUTHWESTERN SAN JACINTO COUNTIES...
    
At 1100 AM CST, a severe thunderstorm capable of producing a tornado
was located 8 miles northwest of North Cleveland, or 10 miles
northwest of Cleveland, moving northeast at 20 mph.

HAZARD...Tornado.

SOURCE...Radar indicated rotation.

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely.

This tornadic thunderstorm will remain over mainly rural areas of
northeastern Montgomery and southwestern San Jacinto Counties.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 3037 9531 3040 9532 3060 9516 3042 9505
TIME...MOT...LOC 1700Z 241DEG 18KT 3042 9523 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...<.75 IN

$$

757 
WWUS54 KHGX 181708
SVSHGX

Severe Weather Statement
National Weather Service Houston/Galveston TX
1108 AM CST Sat Dec 18 2021

TXC339-407-181717-
/O.EXP.KHGX.TO.W.0031.000000T0000Z-211218T1715Z/
Montgomery TX-San Jacinto TX-
1108 AM CST Sat Dec 18 2021

...THE TORNADO WARNING FOR NORTHEASTERN MONTGOMERY AND SOUTHWESTERN
SAN JACINTO COUNTIES WILL EXPIRE AT 1115 AM CST...
                
The storm which prompted the warning has been absorbed by a line of 
thunderstorms, and no longer appears capable of producing a tornado. 
Therefore, the warning will be allowed to expire.  However gusty 
winds and heavy rain are still possible with this thunderstorm.

Remember, a Severe Thunderstorm Warning still remains in effect. 
Though the tornado threat is diminishing, remain in sturdy shelter 
until the damaging wind threat has ended.

LAT...LON 3037 9531 3040 9532 3060 9516 3042 9505
TIME...MOT...LOC 1707Z 241DEG 18KT 3043 9520 

$$

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, 10:39 AM CST	Severe Thunderstorm Warning	HGX	Harris, Montgomery	20 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

Tornado Warnings in Texas, 2021 Every tornado warning in 2021 Tornadoes 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.