Alert archive / Mississippi / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 305, NWS Memphis, TN

July 21, 2018Coahoma County, Mississippi; Phillips County, Arkansas

NWS Memphis, TN issued this severe thunderstorm warning at Jul 21, 2018, 1:12 AM CDT for Coahoma County, Mississippi; Phillips County, Arkansas. It was in force for 48 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: Jul 21, 2018, 1:12 AM CDT (06:12 UTC)
Expired: Jul 21, 2018, 2:00 AM CDT
In force: 48 min
Issued by: NWS Memphis, TN
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Phillips County, AR, Coahoma County, MS

The radar

The Memphis radar (KNQA), 137 km from the middle of the area, began a volume at 06:12 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
Jul 20, 6:22 PM CDT	Tornado Watch	SPC	8 hr

The nearest sounding before it

Little Rock, AR (KBYH), launched 00:00Z, 6.2 hours before the alert went out and 90 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: 3694 J/kg
Mixed-layer CIN: -94 J/kg
Mixed-layer LCL: 1760 m above ground
0-6 km bulk shear: 41 kt
0-1 km storm-relative helicity: 220 m²/s²
0-3 km storm-relative helicity: 407 m²/s²
Significant tornado parameter: 1.2
Supercell composite: 28.4

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 Memphis, TN wrote its last area forecast discussion before this severe thunderstorm warning went out at Jul 20, 11:46 PM CDT, 1 hour 26 minutes earlier.

Area forecast discussion, Jul 20, 11:46 PM CDT, 1 hour 26 minutes before

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Hazardous weather outlook, Jul 20, 8:08 PM CDT, 5 hours 4 minutes before

Hazardous Weather Outlook
National Weather Service Memphis TN
808 PM CDT Fri Jul 20 2018

ARZ008-009-017-018-026>028-035-036-048-049-058-MOZ113-115-
MSZ001>017-020>024-TNZ001>004-019>022-048>055-088>092-220315-
Alcorn-Benton MS-Benton TN-Calhoun-Carroll-Chester-Chickasaw-Clay-
Coahoma-Craighead-Crittenden-Crockett-Cross-DeSoto-Decatur-
Dunklin-Dyer-Fayette-Gibson-Greene-Hardeman-Hardin-Haywood-
Henderson-Henry-Itawamba-Lafayette-Lake-Lauderdale-Lawrence-
Lee AR-Lee MS-Madison-Marshall-McNairy-Mississippi-Monroe-Obion-
Panola-Pemiscot-Phillips-Poinsett-Pontotoc-Prentiss-Quitman-
Randolph-Shelby-St. Francis-Tallahatchie-Tate-Tippah-Tipton-
Tishomingo-Tunica-Union-Weakley-Yalobusha-
808 PM CDT Fri Jul 20 2018

This hazardous weather outlook is for portions of East Arkansas...
the Missouri Bootheel...North Mississippi...and West Tennessee.

.DAY ONE...Tonight

An outbreak of severe thunderstorms is expected tonight. There is
a Moderate Risk for Severe Thunderstorms across northwest
Tennessee, with an Enhanced Risk of Severe Thunderstorms across
the remainder of the area. The potential will exist for very large
hail, some golfball size or larger, damaging winds, and a few
tornadoes. Please continue to monitor the weather through the
night and be prepared to take cover if warnings are issued for
your location.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will likely be needed across the Mid-South
tonight.

KRM

In the hours before

Special weather statement, Jul 21, 1:09 AM CDT, 3 minutes before

Special Weather Statement
National Weather Service Memphis TN
109 AM CDT SAT JUL 21 2018

ARZ058-MSZ010-210645-
Phillips AR-Coahoma MS-
109 AM CDT SAT JUL 21 2018

...A SIGNIFICANT WEATHER ADVISORY HAS BEEN ISSUED UNTIL 145 AM CDT
FOR...

Southwestern Phillips County in eastern Arkansas...
West central Coahoma County in northwestern Mississippi...

At 109 AM CDT...a strong thunderstorm producing pea size hail or
larger and winds at least 40 mph was located near St. Charles, or 10
miles northwest of Elaine, moving east at 5 mph.

Very heavy rain along with continuous cloud to ground lightning are
also possible with this thunderstorm.

People in southwestern Phillips and west central Coahoma Counties
should monitor this storm closely.

LAT...LON 3414 9108 3419 9109 3420 9109 3420 9107
      3422 9106 3425 9108 3426 9106 3428 9108
      3430 9107 3429 9106 3431 9106 3432 9105
      3432 9106 3434 9106 3434 9100 3444 9100
      3426 9067 3412 9066 3412 9112
TIME...MOT...LOC 0609Z 281DEG 6KT 3437 9102

The office that day

Everything else NWS Memphis, TN issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 20, 9:37 PM CDT	Severe Thunderstorm Warning	MEG	Coahoma, Tunica	38 min
Jul 20, 10:06 PM CDT	Severe Thunderstorm Warning	MEG	Coahoma, Quitman, Tunica	22 min
Jul 20, 10:22 PM CDT	Tornado Warning	MEG	Coahoma	38 min
Jul 20, 11:06 PM CDT	Severe Thunderstorm Warning	MEG	Coahoma	39 min
Jul 20, 11:40 PM CDT	Severe Thunderstorm Warning	MEG	Coahoma	27 min
Jul 21, 1:55 AM CDT	Special Weather Statement	MEG	Coahoma	50 min
Jul 21, 3:49 AM CDT	Severe Thunderstorm Warning	MEG	Coahoma	41 min
Jul 21, 3:55 AM CDT	Special Weather Statement	MEG	Tunica	35 min
Jul 20, 9:07 PM CDT	Severe Thunderstorm Warning	MEG	Lee, Phillips	38 min
Jul 21, 1:09 AM CDT	Special Weather Statement	MEG	Phillips	36 min

Nearby

Severe Thunderstorm Warnings in Mississippi, 2018 Severe Thunderstorm Warnings in Arkansas, 2018 Every severe thunderstorm warning 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.