Alert archive / Mississippi / Tornado Watches in 2017

Tornado Watch 287

May 27, 20174 counties in Arkansas; 15 counties in Mississippi; 13 counties in Tennessee

The Storm Prediction Center issued this tornado watch at May 27, 2017, 9:59 PM CDT for 4 counties in Arkansas; 15 counties in Mississippi; 13 counties in Tennessee. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
May 27, 2017, 9:59 PM CDT (02:59 UTC)
Expired
May 28, 2017, 12:21 AM CDT
In force
2 hr
Issued by
the Storm Prediction Center
Largest hail expected
2 in
Strongest gust expected
70 kt
All 32 counties

Crittenden County, AR, Cross County, AR, Lee County, AR, St. Francis County, AR, Alcorn County, MS, Benton County, MS, DeSoto County, MS, Itawamba County, MS, Lafayette County, MS, Lee County, MS, Marshall County, MS, Panola County, MS, Pontotoc County, MS, Prentiss County, MS, Tate County, MS, Tippah County, MS, Tishomingo County, MS, Tunica County, MS, Union County, MS, Chester County, TN, Crockett County, TN, Decatur County, TN, Fayette County, TN, Hardeman County, TN, Hardin County, TN, Haywood County, TN, Henderson County, TN, Lauderdale County, TN, Madison County, TN, McNairy County, TN, Shelby County, TN, Tipton County, TN

The radar

The Memphis radar (KNQA), 10 km from the middle of the area, began a volume at 03:02 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
30%
Ten or more severe hail reports
30%
One or more hailstones of 2 inches or more
30%
Six or more combined severe hail and wind reports
80%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
May 27, 10:00 PM CDTSevere Thunderstorm WarningMEGCrockett, Dyer, Gibson, Haywood, Lauderdale, Madison45 min
May 27, 10:29 PM CDTSevere Thunderstorm WarningMEGCrittenden, Cross, Mississippi, Poinsett46 min
May 27, 10:38 PM CDTSevere Thunderstorm WarningMEGCarroll, Crockett, Dyer, Gibson, Haywood, Lauderdale and 1 more52 min
May 27, 10:49 PM CDTSevere Thunderstorm WarningMEGChester, Decatur, Hardin, Henderson, McNairy, Madison41 min
May 27, 10:51 PM CDTSevere Thunderstorm WarningMEGCrittenden, St. Francis54 min
May 27, 11:04 PM CDTSevere Thunderstorm WarningMEGCrittenden41 min
May 27, 11:14 PM CDTTornado WarningMEGChester, Decatur, Hardin, Henderson13 min
May 27, 11:23 PM CDTSevere Thunderstorm WarningMEGChester, Decatur, Hardeman, Hardin, Henderson, McNairy and 1 more52 min
May 27, 11:41 PM CDTSevere Thunderstorm WarningMEGCrittenden36 min
May 27, 11:43 PM CDTSevere Thunderstorm WarningMEGAlcorn, Benton, Itawamba, Lee, Prentiss, Tippah and 2 more62 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

Little Rock, AR (KBYH), launched 00:00Z, 3.0 hours before the alert went out and 52 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, Little Rock, AR at 00:00Z on 2017-05-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 3385 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, Little Rock, AR at 00:00Z on 2017-05-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 113 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
3385 J/kg
Mixed-layer CIN
-56 J/kg
Mixed-layer LCL
1096 m above ground
0-6 km bulk shear
49 kt
0-1 km storm-relative helicity
113 m²/s²
0-3 km storm-relative helicity
157 m²/s²
Significant tornado parameter
2.5
Supercell composite
15.1

Open this sounding in Storm Lab

The text

As transmitted.

927 
WWUS20 KWNS 280257
SEL7  
SPC WW 280257
ARZ000-MSZ000-TNZ000-281000-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 287
NWS Storm Prediction Center Norman OK
1000 PM CDT Sat May 27 2017

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  Eastern Arkansas
  Northern Mississippi
  Western Tennessee

* Effective this Saturday night and Sunday morning from 1000 PM
  until 500 AM CDT.

* Primary threats include...
  A couple tornadoes possible
  Isolated significant damaging wind gusts to 80 mph possible
  Isolated very large hail events to 2 inches in diameter possible

SUMMARY...A fast-moving convective line will continue to move
southeastward across eastern Arkansas into western Tennessee,
including the Memphis metro area. The most intense storms will favor
areas along and south/southwest of an arcing outflow boundary, with
widespread damaging winds a distinct possibility aside from some
line-embedded tornado risk. These storms will eventually move into
northern Mississippi overnight.

The tornado watch area is approximately along and 50 statute miles
north and south of a line from 35 miles south southwest of Jonesboro
AR to 50 miles northeast of Tupelo MS. For a complete depiction of
the watch see the associated watch outline update (WOUS64 KWNS
WOU7).

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.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 279...WW 280...WW
281...WW 282...WW 284...WW 285...WW 286...

AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 2 inches. Extreme turbulence and surface wind
gusts to 70 knots. A few cumulonimbi with maximum tops to 600. Mean
storm motion vector 30035.

...Guyer

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 27, 7:01 PM CDTTornado WatchSPCBaxter, Boone, Clay, Cleburne, Conway, Craighead and 20 more6 hr
May 27, 9:26 PM CDTMesoscale DiscussionSPCClay, Craighead, Crittenden, Cross, Greene, Independence and 8 more94 min
May 27, 11:47 PM CDTMesoscale DiscussionSPCCrawford, Sebastian, Washington58 min
May 28, 12:06 AM CDTSevere Thunderstorm WatchSPCBenton, Carroll, Columbia, Crawford, Franklin, Hempstead and 10 more5 hr
May 28, 12:18 AM CDTSevere Thunderstorm WatchSPCArkansas, Bradley, Calhoun, Clark, Cleburne, Cleveland and 36 more6 hr
May 28, 12:52 AM CDTMesoscale DiscussionSPCHoward, Montgomery, Polk23 min
May 28, 2:11 AM CDTMesoscale DiscussionSPCArkansas, Clark, Cleveland, Dallas, Desha, Faulkner and 12 more2 hr
May 28, 2:53 AM CDTMesoscale DiscussionSPCColumbia, Hempstead, Howard, Lafayette, Little River, Miller and 6 more2 hr
May 28, 4:59 AM CDTMesoscale DiscussionSPCAshley, Bradley, Calhoun, Chicot, Cleveland, Columbia and 9 more2 hr
May 27, 11:46 PM CDTMesoscale DiscussionSPCCalhoun, Carroll, Chickasaw, Choctaw, Clay, Grenada and 12 more59 min
May 28, 10:59 AM CDTMesoscale DiscussionSPCGeorge, Hancock, Harrison, Jackson, Pearl River, Stone2 hr
May 27, 7:02 PM CDTMesoscale DiscussionSPCBedford, Cannon, Cheatham, Coffee, Davidson, DeKalb and 18 more58 min
May 27, 9:07 PM CDTSevere Thunderstorm WatchSPCFranklin, Giles, Lawrence, Lincoln, Moore, Wayne8 hr
May 27, 9:46 PM CDTMesoscale DiscussionSPCAnderson, Bledsoe, Blount, Bradley, Carter, Claiborne and 24 more89 min

Nearby

Tornado Watches in Mississippi, 2017Tornado Watches in Tennessee, 2017Tornado Watches in Arkansas, 2017Every tornado watch in 2017

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.