Alert archive / Texas / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 116, NWS Houston/Galveston, TX

December 31, 2020Brazoria County, Texas

NWS Houston/Galveston, TX issued this severe thunderstorm warning at Dec 31, 2020, 10:03 AM CST for Brazoria County, Texas. It was in force for 29 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Dec 31, 2020, 10:03 AM CST (16:03 UTC)
Expired: Dec 31, 2020, 10:32 AM CST
In force: 29 min
Issued by: NWS Houston/Galveston, TX
Area: Storm-based polygon
Tornado: Possible
Hail: 0.75 in
Wind: 60.0 mph

County Brazoria County, TX

The radar

The Houston radar (KHGX), 48 km from the middle of the area, began a volume at 16:06 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Dec 31, 7:40 AM CST	Tornado Watch	SPC	7 hr

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 12:00Z, 4.1 hours before the alert went out and 240 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: 238 J/kg
Mixed-layer CIN: -8 J/kg
Mixed-layer LCL: 492 m above ground
0-6 km bulk shear: 58 kt
0-1 km storm-relative helicity: 181 m²/s²
0-3 km storm-relative helicity: 209 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 1.9

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Houston/Galveston, TX wrote its last area forecast discussion before this severe thunderstorm warning went out at Dec 31, 4:14 AM CST, 5 hours 49 minutes earlier.

Area forecast discussion, Dec 31, 4:14 AM CST, 5 hours 49 minutes before

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In the hours before

Special weather statement, Dec 31, 9:18 AM CST, 45 minutes before

Special Weather Statement
National Weather Service Houston/Galveston TX
918 AM CST Thu Dec 31 2020

TXZ236-237-336-337-436-311600-
Inland Brazoria TX-Coastal Matagorda TX-Inland Matagorda TX-
Matagorda Islands TX-Coastal Brazoria TX-
918 AM CST Thu Dec 31 2020

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN BRAZORIA AND CENTRAL
MATAGORDA COUNTIES UNTIL 1000 AM CST...

At 916 AM CST, Doppler radar was tracking a strong thunderstorm 12
miles southeast of Matagorda, moving north at 35 mph.

Pea size hail and wind gusts up to 50 mph will be possible with this
storm.

Locations impacted include...
Matagorda, Bay City, Sargent and Wadsworth.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy rainfall is also occurring with this storm, and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in League City.

&&

A Tornado Watch remains in effect until 300 PM CST for southeastern
Texas.

LAT...LON 2845 9605 2898 9601 2903 9570 2896 9550
      2861 9561 2845 9596
TIME...MOT...LOC 1516Z 189DEG 31KT 2858 9580

Special weather statement, Dec 31, 9:34 AM CST, 29 minutes before

Special Weather Statement
National Weather Service Houston/Galveston TX
934 AM CST Thu Dec 31 2020

TXZ214-438-311630-
Galveston Island and Bolivar Peninsula TX-Chambers TX-
934 AM CST Thu Dec 31 2020

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN GALVESTON...CHAMBERS
AND SOUTHEASTERN LIBERTY COUNTIES UNTIL 1030 AM CST...

At 934 AM CST, Doppler radar was tracking a strong thunderstorm near
Rollover Pass, or 19 miles northeast of Galveston Pier 21, moving
north at 30 mph.

Winds in excess of 40 mph will be possible with this storm.

Locations impacted include...
Anahuac, Gilchrist, Rollover Pass, Bolivar Peninsula, High Island,
Crystal Beach, Stowell, Winnie and Oak Island.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy rainfall is also occurring with this storm, and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

A Tornado Watch remains in effect until 300 PM CST for southeastern
Texas.

LAT...LON 2955 9439 2949 9436 2939 9470 2982 9470
      2989 9455 2989 9436 2956 9435
TIME...MOT...LOC 1534Z 177DEG 25KT 2945 9450

Special weather statement, Dec 31, 9:44 AM CST, 19 minutes before

Special Weather Statement
National Weather Service Houston/Galveston TX
944 AM CST Thu Dec 31 2020

TXZ236-237-336-337-436-437-311645-
Inland Brazoria TX-Coastal Matagorda TX-Inland Matagorda TX-
Matagorda Islands TX-Brazoria Islands TX-Coastal Brazoria TX-
944 AM CST Thu Dec 31 2020

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN WHARTON...
SOUTHWESTERN BRAZORIA AND NORTHEASTERN MATAGORDA COUNTIES UNTIL 1045
AM CST...

At 942 AM CST, Doppler radar was tracking a strong thunderstorm near
Sargent, or 14 miles south of Sweeny, moving north at 30 mph.

Winds in excess of 40 mph will be possible with this storm.

Locations impacted include...
West Columbia, Sweeny, Brazoria, Sargent, Van Vleck, Wild Peach
Village and Damon.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy rainfall is also occurring with this storm, and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

A Tornado Watch remains in effect until 300 PM CST for southeastern
Texas.

LAT...LON 2862 9590 2920 9591 2930 9576 2924 9557
      2880 9553
TIME...MOT...LOC 1542Z 177DEG 24KT 2885 9576

Special weather statement, Dec 31, 9:52 AM CST, 11 minutes before

Special Weather Statement
National Weather Service Houston/Galveston TX
952 AM CST Thu Dec 31 2020

TXZ237-337-437-311645-
Inland Brazoria TX-Brazoria Islands TX-Coastal Brazoria TX-
952 AM CST Thu Dec 31 2020

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN BRAZORIA COUNTY
UNTIL 1045 AM CST...

At 951 AM CST, Doppler radar was tracking a strong thunderstorm near
Surfside Beach, moving north at 30 mph.

Winds in excess of 40 mph will be possible with this storm.

Locations impacted include...
Freeport, Clute, Surfside Beach, Richwood, Danbury, Oyster Creek and
Liverpool.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy rainfall is also occurring with this storm, and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

A Tornado Watch remains in effect until 300 PM CST for southeastern
Texas.

LAT...LON 2886 9521 2881 9541 2926 9539 2931 9523
      2926 9511
TIME...MOT...LOC 1551Z 186DEG 25KT 2888 9532

The office that day

Everything else NWS Houston/Galveston, TX issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 30, 7:31 PM CST	Areal Flood Advisory	HGX	Austin, Colorado, Fort Bend, Waller, Wharton	3 hr
Dec 30, 7:56 PM CST	Areal Flood Advisory	HGX	Harris, Montgomery, Waller	3 hr
Dec 30, 9:28 PM CST	Flash Flood Warning	HGX	Austin, Fort Bend, Jackson, Wharton	3 hr
Dec 30, 9:32 PM CST	Areal Flood Advisory	HGX	Grimes, Harris, Montgomery, Walker	3 hr
Dec 30, 9:36 PM CST	Areal Flood Advisory	HGX	Jackson, Matagorda, Wharton	3 hr
Dec 30, 11:36 PM CST	Areal Flood Advisory	HGX	Austin, Fort Bend, Waller	2 hr
Dec 31, 12:30 AM CST	Areal Flood Advisory	HGX	Jackson	90 min
Dec 31, 1:14 AM CST	Areal Flood Advisory	HGX	Austin, Waller, Washington	2 hr
Dec 31, 7:03 AM CST	Areal Flood Advisory	HGX	Colorado, Fort Bend, Jackson, Matagorda, Wharton	3 hr
Dec 31, 7:42 AM CST	River Flood Warning	HGX	Austin, Colorado, Fort Bend, Wharton	4 days
Dec 31, 8:58 AM CST	Special Marine Warning	HGX		32 min
Dec 31, 9:02 AM CST	Special Marine Warning	HGX		43 min
Dec 31, 9:04 AM CST	Special Marine Warning	HGX		56 min
Dec 31, 9:18 AM CST	Special Weather Statement	HGX	Matagorda	42 min
Dec 31, 9:24 AM CST	Special Marine Warning	HGX		51 min
Dec 31, 9:34 AM CST	Special Weather Statement	HGX	Chambers	56 min
Dec 31, 9:44 AM CST	Special Weather Statement	HGX	Matagorda	61 min
Dec 31, 9:45 AM CST	Wind Advisory	HGX	Brazoria, Galveston, Matagorda	17 hr
Dec 31, 9:52 AM CST	Special Weather Statement	HGX	Brazoria	53 min
Dec 31, 9:58 AM CST	Special Marine Warning	HGX		32 min
Dec 31, 10:03 AM CST	Special Marine Warning	HGX		87 min
Dec 31, 10:23 AM CST	Special Marine Warning	HGX		52 min
Dec 31, 10:25 AM CST	Special Marine Warning	HGX		95 min
Dec 31, 10:42 AM CST	Special Weather Statement	HGX	Chambers	48 min
Dec 31, 11:03 AM CST	Areal Flood Warning	HGX	Waller	3 hr
Dec 31, 11:21 AM CST	Areal Flood Advisory	HGX	Fort Bend, Harris	114 min
Dec 31, 11:25 AM CST	Special Marine Warning	HGX		95 min
Dec 31, 11:31 AM CST	Areal Flood Advisory	HGX	Brazoria, Galveston, Harris	3 hr
Dec 31, 11:51 AM CST	Flash Flood Warning	HGX	Brazoria, Galveston	114 min
Dec 31, 11:58 AM CST	Special Weather Statement	HGX	Chambers, Galveston, Liberty	62 min
Dec 31, 12:57 PM CST	Special Marine Warning	HGX		63 min
Dec 31, 1:09 PM CST	River Flood Warning	HGX	Harris	23 hr
Dec 31, 1:26 PM CST	Areal Flood Advisory	HGX	Chambers, Galveston, Liberty	2 hr
Dec 31, 2:05 PM CST	Areal Flood Warning	HGX	Waller	6 hr
Dec 31, 2:13 PM CST	Areal Flood Warning	HGX	Harris, Montgomery, Waller	10 hr
Dec 31, 2:29 PM CST	Areal Flood Warning	HGX	Brazoria, Galveston	6 hr
Dec 31, 2:38 PM CST	River Flood Warning	HGX	Brazoria, Fort Bend, Wharton	8 days
Dec 31, 2:42 PM CST	River Flood Warning	HGX	Matagorda, Wharton	43 hr
Dec 31, 3:11 PM CST	Rip Current Statement	HGX	Brazoria, Galveston, Matagorda	9 hr

Nearby

Severe Thunderstorm Warnings in Texas, 2020 Every severe thunderstorm warning in 2020

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.