Alert archive / Mississippi / Severe Thunderstorm Watches in 2021

Severe Thunderstorm Watch 161

May 9, 20218 counties in Alabama; 8 parishes in Louisiana; 29 counties in Mississippi

The Storm Prediction Center issued this severe thunderstorm watch at May 9, 2021, 7:29 PM CDT for 8 counties in Alabama; 8 parishes in Louisiana; 29 counties in Mississippi. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued: May 9, 2021, 7:29 PM CDT (00:29 UTC)
Expired: May 9, 2021, 11:40 PM CDT
In force: 4 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1.5 in
Strongest gust expected: 60 kt

All 45 counties

Fayette County, AL, Franklin County, AL, Lamar County, AL, Marion County, AL, Pickens County, AL, Tuscaloosa County, AL, Walker County, AL, Winston County, AL, Catahoula Parish, LA, Concordia Parish, LA, East Carroll Parish, LA, Franklin Parish, LA, Madison Parish, LA, Richland Parish, LA, Tensas Parish, LA, West Carroll Parish, LA, Adams County, MS, Attala County, MS, Carroll County, MS, Choctaw County, MS, Claiborne County, MS, Clay County, MS, Copiah County, MS, Grenada County, MS, Hinds County, MS, Holmes County, MS, Humphreys County, MS, Issaquena County, MS, Jefferson County, MS, Kemper County, MS, Leake County, MS, Leflore County, MS, Lowndes County, MS, Madison County, MS, Montgomery County, MS, Neshoba County, MS, Noxubee County, MS, Oktibbeha County, MS, Rankin County, MS, Scott County, MS, Sharkey County, MS, Warren County, MS, Webster County, MS, Winston County, MS, Yazoo County, MS

The radar

The Jackson/Brandon,MS radar (KDGX), 77 km from the middle of the area, began a volume at 00:31 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: 20%
One or more EF2 to EF5 tornadoes: 5%
Ten or more severe wind reports: 60%
One or more gusts of 65 knots or more: 20%
Ten or more severe hail reports: 60%
One or more hailstones of 2 inches or more: 20%
Six or more combined severe hail and wind reports: 95%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
May 9, 7:57 PM CDT	Severe Thunderstorm Warning	JAN	Clay, Webster	43 min
May 9, 7:59 PM CDT	Severe Thunderstorm Warning	BMX	Lamar, Marion	45 min
May 9, 8:21 PM CDT	Severe Thunderstorm Warning	JAN	Lowndes	28 min
May 9, 9:06 PM CDT	Severe Thunderstorm Warning	JAN	East Carroll	39 min
May 9, 9:08 PM CDT	Severe Thunderstorm Warning	JAN	West Carroll	37 min
May 9, 9:36 PM CDT	Severe Thunderstorm Warning	JAN	Yazoo	37 min
May 9, 9:45 PM CDT	Severe Thunderstorm Warning	JAN	East Carroll	60 min
May 9, 10:12 PM CDT	Severe Thunderstorm Warning	JAN	Warren, Yazoo	62 min
May 9, 10:16 PM CDT	Severe Thunderstorm Warning	JAN	Holmes, Humphreys, Yazoo	35 min
May 9, 10:24 PM CDT	Flash Flood Warning	JAN	Holmes, Humphreys, Sharkey, Yazoo	86 min
May 9, 10:34 PM CDT	Flash Flood Warning	JAN	Carroll, Choctaw, Clay, Lowndes, Montgomery, Oktibbeha and 1 more	78 min
May 9, 10:38 PM CDT	Severe Thunderstorm Warning	JAN	Hinds, Madison, Rankin	82 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

Jackson, MS (KJAN), launched 00:00Z, 0.5 hours before the alert went out and 73 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: 632 J/kg
Mixed-layer CIN: -123 J/kg
Mixed-layer LCL: 935 m above ground
0-6 km bulk shear: 57 kt
0-1 km storm-relative helicity: 212 m²/s²
0-3 km storm-relative helicity: 205 m²/s²
Significant tornado parameter: 0.5
Supercell composite: 1.1

Open this sounding in Storm Lab

The text

As transmitted.

434 
WWUS20 KWNS 100027
SEL1  
SPC WW 100027
ALZ000-LAZ000-MSZ000-100700-

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 161
NWS Storm Prediction Center Norman OK
730 PM CDT Sun May 9 2021

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  Northwest Alabama
  Northeast Louisiana
  Central Mississippi

* Effective this Sunday night and Monday morning from 730 PM
  until 200 AM CDT.

* Primary threats include...
  Scattered damaging wind gusts to 70 mph likely
  Scattered large hail events to 1.5 inches in diameter likely
  A tornado or two possible

SUMMARY...A fast-moving cluster of storms over northern Mississippi
will track into northwest Alabama, while other strong storms develop
across central Mississippi.  All of this activity will pose a risk
of locally damaging wind gusts and hail through the early overnight
hours.

The severe thunderstorm watch area is approximately along and 50
statute miles north and south of a line from 45 miles northwest of
Natchez MS to 55 miles north northeast of Tuscaloosa AL. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU1).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for 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. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 157...WW 158...WW
159...WW 160...

AVIATION...A few severe thunderstorms with hail surface and aloft to
1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 450. Mean storm motion vector
27030.

...Hart

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 9, 9:32 PM CDT	Mesoscale Discussion	SPC	Fayette, Greene, Lamar, Marion, Pickens, Tuscaloosa and 2 more	118 min
May 10, 5:22 PM CDT	Mesoscale Discussion	SPC	Caldwell, Catahoula, Concordia, Franklin, Grant, Jackson and 3 more	2 hr

Nearby

Severe Thunderstorm Watches in Mississippi, 2021 Severe Thunderstorm Watches in Alabama, 2021 Severe Thunderstorm Watches in Louisiana, 2021 Every severe thunderstorm watch 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.