Alert archive / Texas / Tornado Watches in 2018

Tornado Watch 22

March 28, 201818 parishes in Louisiana; 30 counties in Texas

The Storm Prediction Center issued this tornado watch at Mar 28, 2018, 12:03 PM CDT for 18 parishes in Louisiana; 30 counties in Texas. It was in force for 9 hr.

The area

The outline as issued.

The facts

Issued
Mar 28, 2018, 12:03 PM CDT (17:03 UTC)
Expired
Mar 28, 2018, 9:00 PM CDT
In force
9 hr
Issued by
the Storm Prediction Center
Largest hail expected
2 in
Strongest gust expected
60 kt
All 48 counties

Allen Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Bienville Parish, LA, Calcasieu Parish, LA, Caldwell Parish, LA, De Soto Parish, LA, Evangeline Parish, LA, Grant Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Rapides Parish, LA, Red River Parish, LA, Sabine Parish, LA, Vernon Parish, LA, Winn Parish, LA, Angelina County, TX, Austin County, TX, Brazoria County, TX, Chambers County, TX, Colorado County, TX, Fort Bend County, TX, Galveston County, TX, Grimes County, TX, Hardin County, TX, Harris County, TX, Jackson County, TX, Jasper County, TX, Jefferson County, TX, Liberty County, TX, Matagorda County, TX, Montgomery County, TX, Nacogdoches County, TX, Newton County, TX, Orange County, TX, Polk County, TX, Sabine County, TX, San Augustine County, TX, San Jacinto County, TX, Shelby County, TX, Trinity County, TX, Tyler County, TX, Walker County, TX, Waller County, TX, Washington County, TX, Wharton County, TX

The radar

The Houston radar (KHGX), 134 km from the middle of the area, began a volume at 17:04 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
40%
One or more EF2 to EF5 tornadoes
20%
Ten or more severe wind reports
30%
One or more gusts of 65 knots or more
20%
Ten or more severe hail reports
40%
One or more hailstones of 2 inches or more
30%
Six or more combined severe hail and wind reports
60%

Warnings issued inside it

12 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

IssuedProductOfficeCountiesLasted
Mar 28, 2:00 PM CDTFlash Flood WarningHGXBrazos, Burleson, Grimes, Washington2 hr
Mar 28, 3:01 PM CDTSevere Thunderstorm WarningSHVBienville, Jackson, Natchitoches, Winn59 min
Mar 28, 3:25 PM CDTTornado WarningSHVJackson, Natchitoches, Winn35 min
Mar 28, 3:55 PM CDTSevere Thunderstorm WarningSHVCaldwell, Grant, Jackson, LaSalle, Ouachita, Winn50 min
Mar 28, 3:59 PM CDTTornado WarningSHVCaldwell, LaSalle, Winn31 min
Mar 28, 4:16 PM CDTTornado WarningSHVJackson, Ouachita29 min
Mar 28, 4:26 PM CDTTornado WarningSHVCaldwell34 min
Mar 28, 4:37 PM CDTSevere Thunderstorm WarningHGXFort Bend, Harris, Waller23 min
Mar 28, 4:42 PM CDTSevere Thunderstorm WarningSHVCaldwell, LaSalle, Ouachita33 min
Mar 28, 4:56 PM CDTSevere Thunderstorm WarningSHVGrant, LaSalle, Natchitoches, Winn53 min
Mar 28, 5:00 PM CDTTornado WarningSHVGrant, LaSalle, Winn30 min
Mar 28, 5:30 PM CDTTornado WarningHGXHarris15 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, 5.1 hours before the alert went out and 169 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-pSkew-T log-p diagram, Lake Charles Mun, LA at 12:00Z on 2018-03-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 295 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Lake Charles Mun, LA at 12:00Z on 2018-03-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 159 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
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
295 J/kg
Mixed-layer CIN
-6 J/kg
Mixed-layer LCL
650 m above ground
0-6 km bulk shear
47 kt
0-1 km storm-relative helicity
159 m²/s²
0-3 km storm-relative helicity
215 m²/s²
Significant tornado parameter
0.2
Supercell composite
3.6

Open this sounding in Storm Lab

The text

As transmitted.

322 
WWUS20 KWNS 281700
SEL2  
SPC WW 281700
LAZ000-TXZ000-CWZ000-290200-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 22
NWS Storm Prediction Center Norman OK
1200 PM CDT Wed Mar 28 2018

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  Western and central Louisiana
  Southeast and east Texas
  Coastal Waters

* Effective this Wednesday afternoon and evening from NOON until
  900 PM CDT.

* Primary threats include...
  A couple tornadoes possible
  Scattered large hail and isolated very large hail events to 2
    inches in diameter possible
  Isolated damaging wind gusts to 70 mph possible

SUMMARY...Severe thunderstorms are expected to become more common
across the watch area through the remainder of the afternoon,
offering damaging gusts, isolated large hail, and the potential for
a couple tornadoes.

The tornado watch area is approximately along and 75 statute miles
north and south of a line from 65 miles north northwest of Palacios
TX to 25 miles north northeast of Alexandria LA. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU2).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Tornado Watch means conditions are favorable for
tornadoes and severe thunderstorms in and close to the watch
area. Persons in these areas should be on the lookout for
threatening weather conditions and listen for later statements
and possible warnings.

&&

AVIATION...TORNADOES and A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE and ALOFT TO 2 INCHES. EXTREME TURBULENCE and SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 25030.


...Edwards

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Mar 28, 11:38 AM CDTMesoscale DiscussionSPCBeauregard, Caldwell, Franklin, Grant, Jackson, LaSalle and 7 more67 min
Mar 28, 2:43 PM CDTMesoscale DiscussionSPCEast Carroll, Franklin, Madison, Morehouse, Richland, Tensas and 1 more92 min
Mar 28, 3:07 PM CDTMesoscale DiscussionSPCAllen, Beauregard, Caldwell, Grant, Jackson, LaSalle and 4 more113 min
Mar 28, 3:27 PM CDTTornado WatchSPCCatahoula, Concordia, East Carroll, Franklin, Madison, Morehouse and 3 more8 hr
Mar 28, 5:32 PM CDTMesoscale DiscussionSPCMadison, Tensas118 min
Mar 28, 5:48 PM CDTMesoscale DiscussionSPCAllen, Beauregard, Calcasieu, Evangeline, Grant, LaSalle and 2 more87 min
Mar 27, 9:23 PM CDTMesoscale DiscussionSPCAtascosa, Bandera, Bexar, Blanco, Caldwell, Comal and 20 more97 min
Mar 27, 9:51 PM CDTSevere Thunderstorm WatchSPCAtascosa, Bastrop, Bexar, Caldwell, DeWitt, Dimmit and 15 more5 hr
Mar 27, 11:58 PM CDTMesoscale DiscussionSPCAtascosa, Bastrop, Bexar, Caldwell, Comal, DeWitt and 17 more2 hr
Mar 28, 5:05 AM CDTMesoscale DiscussionSPCBastrop, Brazos, Burleson, Fayette, Grimes, Lee and 1 more85 min
Mar 28, 9:09 AM CDTMesoscale DiscussionSPCAtascosa, Bexar, Frio, Medina, Wilson2 hr
Mar 28, 6:53 PM CDTMesoscale DiscussionSPCBrooks, Cameron, Duval, Hidalgo, Jim Hogg, Jim Wells and 6 more97 min

Nearby

Tornado Watches in Texas, 2018Tornado Watches in Louisiana, 2018Every tornado watch in 2018

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.