Alert archive / Arkansas / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 319, NWS Memphis, TN

August 20, 2018Shelby County, Tennessee; Crittenden County, Cross County, St. Francis County, Arkansas

NWS Memphis, TN issued this severe thunderstorm warning at Aug 20, 2018, 4:57 PM CDT for Shelby County, Tennessee; Crittenden County, Cross County, St. Francis 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: Aug 20, 2018, 4:57 PM CDT (21:57 UTC)
Expired: Aug 20, 2018, 5:45 PM CDT
In force: 48 min
Issued by: NWS Memphis, TN
Area: Storm-based polygon
Hail: 0.75 in
Wind: 70.0 mph

Counties Crittenden County, AR, Cross County, AR, St. Francis County, AR, Shelby County, TN

The radar

The Memphis radar (KNQA), 54 km from the middle of the area, began a volume at 21:56 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
Aug 20, 4:45 PM CDT	Severe Thunderstorm Watch	SPC	6 hr
Aug 20, 12:46 PM CDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Little Rock, AR (KBYH), launched 12:00Z, 10.0 hours before the alert went out and 58 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: 904 J/kg
Mixed-layer CIN: -46 J/kg
Mixed-layer LCL: 737 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 81 m²/s²
0-3 km storm-relative helicity: 133 m²/s²
Significant tornado parameter: 0.5
Supercell composite: 3.7

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 Aug 20, 2:21 PM CDT, 2 hours 36 minutes earlier.

Area forecast discussion, Aug 20, 2:21 PM CDT, 2 hours 36 minutes before

Area Forecast Discussion
National Weather Service Memphis TN
221 PM CDT Mon Aug 20 2018

.DISCUSSION...

Currently...Area of showers and thunderstorms from earlier this
morning has dissipated over West Tennessee and North Mississippi.
Meanwhile an upper low is situated over Northern Missouri with a
cold front extending south into western Arkansas. Thunderstorms
are strengthening along the front over southern Missouri and
northern Arkansas as large scale ascent moves over the frontal
zone. A severe thunderstorm watch is in effect across eastern
Arkansas and the Missouri Bootheel until 8 pm CDT.

This afternoon and tonight...The cold front will push east with
thunderstorms developing along the front and pushing into the Mid-
South after 3 pm CDT. A belt of stronger mid level winds will
rotate around the base of the upper low and into the region. 0-6km
bulk shear values greater than 30 kts should be sufficient for
severe storm organization. Morning showers and thunderstorms have
left an area of stable air across much of the Mid-South. Breaks
in the clouds and southerly winds ahead of the cold front will
start to destabilize from the west where SBCAPEs are already
greater than 3000 j/kg. Expect a broken line of storms to track
across the Mid-South starting around 3 pm in Northeast
Arkansas...6-7 pm at the Mississippi River to 9-11 pm at the TN
River/Northeast Mississippi. The main threat will be bowing line
segments with damaging winds. Large hail is a secondary threat.
0-1 km helicity values will be greater than 100 m2/s2 so a weak
tornado cannot be ruled out. Most of the showers and thunderstorms
should be east of the area by about midnight. Cooler temps will
begin to filter in by morning with many location dipping into the
upper 60s by morning a skies clear out.

Tuesday through Friday...The upper trough and cold front will
push east on Tuesday. The morning will start with some sunshine
but the Mid-South will still be in an area of low level cyclonic
flow so stratocu will redevelop. A few showers will be possible
in the afternoon across eastern sections as surface heating
creates some instability. High temps will be well below normal in
the 80s. The Mid-South will remain in WNW flow through Friday as
dry surface high pressure moves from the Plains across the Ohio
Valley to the Atlantic seaboard. Highs will be the 80s with lows
in the 60s. Some eastern locations will get into the 50s Thursday
and Friday morning. Dewpoints will be in the 60s during this
period which will create some comfortable humidity levels.

Weekend and early next week...Upper level high pressure is
expected to build across the region. Medium range models are in
good agreement. As surface high pressure shifts east and winds
turns southerly expect humidities to climb. Temperatures will
climb back to normal or slightly above with readings in the lower
90s. Heat index values will climb back in the low 100s as well.
Looks like summer isn't over yet.

SJM

&&

.AVIATION...

18z TAF Cycle

Flight category will vary throughout the period as a line of
storms moves through the region. Winds will be from the south and
gusty this afternoon ahead of the front, but will subside and
become more westerly by late in the period. Have currently
prevailed VCTS for much of the PM hours at all terminals and timed
TSRA with TEMPO based on latest thinking, but uncertainty
remains.

Conditions should recover back to VFR conditions by early morning
hours. Some fog development could hinder MKL visibility, but too
much uncertainty coupled with focus on storm timing led to the
omission of that at this time.

ZDM

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&

Hazardous weather outlook, Aug 20, 4:54 PM CDT, 3 minutes before

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In the hours before

Special weather statement, Aug 20, 4:07 PM CDT, 50 minutes before

Special Weather Statement
National Weather Service Memphis TN
407 PM CDT MON AUG 20 2018

ARZ058-MSZ007-010-202145-
Phillips AR-Tunica MS-Coahoma MS-
407 PM CDT MON AUG 20 2018

...A SIGNIFICANT WEATHER ADVISORY HAS BEEN ISSUED UNTIL 445 PM CDT
FOR...

Northeastern Phillips County in eastern Arkansas...
Southwestern Tunica County in northwestern Mississippi...
Northeastern Coahoma County in northwestern Mississippi...

At 406 PM CDT...a strong thunderstorm producing pea size hail or
larger and winds to 50 mph was located near Friars Point, or 8 miles
southwest of Helena, moving east at 25 mph.

People in northeastern Phillips...southwestern Tunica and
northeastern Coahoma Counties should monitor this storm closely.

LAT...LON 3458 9041 3442 9037 3442 9040 3437 9040
      3434 9082 3450 9084
TIME...MOT...LOC 2106Z 253DEG 21KT 3443 9069

Special weather statement, Aug 20, 4:07 PM CDT, 50 minutes before

Special Weather Statement
National Weather Service Memphis TN
407 PM CDT MON AUG 20 2018

ARZ058-MSZ007-010-202145-
Phillips AR-Tunica MS-Coahoma MS-
407 PM CDT MON AUG 20 2018

...A SIGNIFICANT WEATHER ADVISORY HAS BEEN ISSUED UNTIL 445 PM CDT
FOR...

Northeastern Phillips County in eastern Arkansas...
Southwestern Tunica County in northwestern Mississippi...
Northeastern Coahoma County in northwestern Mississippi...

At 407 PM CDT...a strong thunderstorm producing pea size hail or
larger and winds at least 40 mph was located near Helena, moving east
at 25 mph.

People in northeastern Phillips...southwestern Tunica and
northeastern Coahoma Counties should monitor this storm closely.

LAT...LON 3458 9041 3442 9037 3442 9040 3437 9040
      3434 9082 3450 9084
TIME...MOT...LOC 2107Z 253DEG 21KT 3446 9055

Special weather statement, Aug 20, 4:13 PM CDT, 44 minutes before

Special Weather Statement
National Weather Service Memphis TN
413 PM CDT MON AUG 20 2018

ARZ008-009-202200-
Randolph AR-Clay AR-
413 PM CDT MON AUG 20 2018

...A SIGNIFICANT WEATHER ADVISORY HAS BEEN ISSUED UNTIL 500 PM CDT
FOR...

Northeastern Randolph County in eastern Arkansas...
Northwestern Clay County in eastern Arkansas...

At 413 PM CDT...a strong thunderstorm producing pea size hail and
winds to 45 mph was located near Success, or 10 miles south of
Doniphan, moving east at 25 mph.

Very heavy rain along with continuous cloud to ground lightning
will occur with this thunderstorm.

People in northeastern Randolph and northwestern Clay Counties should
monitor this storm closely.

LAT...LON 3650 9037 3636 9035 3629 9100 3650 9098
TIME...MOT...LOC 2113Z 264DEG 21KT 3647 9081

Local storm report, Aug 20, 4:41 PM CDT, 16 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MEMPHIS TN
441 PM CDT MON AUG 20 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0437 PM     HAIL             SE LULA                 34.45N 90.48W
08/20/2018  M0.75 INCH       COAHOMA            MS   STORM CHASER

&&

MRM

Special weather statement, Aug 20, 4:45 PM CDT, 12 minutes before

Special Weather Statement
National Weather Service Memphis TN
445 PM CDT MON AUG 20 2018

ARZ009-202200-
Clay AR-
445 PM CDT MON AUG 20 2018

...A SIGNIFICANT WEATHER ADVISORY HAS BEEN ISSUED UNTIL 500 PM CDT
FOR...

Northwestern Clay County in eastern Arkansas...

At 444 PM CDT...a strong thunderstorm producing dime size hail and
winds to 50 mph was located over Success, or near Corning, moving
east at 35 mph.

Very heavy rain along with continuous cloud to ground lightning are
will occur with this thunderstorm.

People in northwestern Clay County should monitor this storm closely.

LAT...LON 3650 9035 3634 9075 3641 9075 3641 9077
      3642 9077 3642 9076 3643 9078 3643 9077
      3644 9078 3649 9077 3650 9078
TIME...MOT...LOC 2144Z 248DEG 28KT 3646 9068

Local storm report, Aug 20, 4:52 PM CDT, 5 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MEMPHIS TN
452 PM CDT MON AUG 20 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0450 PM     HAIL             6 WNW DARLING           34.38N 90.36W
08/20/2018  E1.25 INCH       QUITMAN            MS   TRAINED SPOTTER

            QUARTER TO HALF DOLLAR SIZED HAIL REPORTED.

&&

MRM

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 20, 11:05 AM CDT	Special Weather Statement	MEG	Shelby	40 min
Aug 20, 5:39 PM CDT	Severe Thunderstorm Warning	MEG	Fayette, Shelby, Tipton	51 min
Aug 20, 5:41 PM CDT	Severe Thunderstorm Warning	MEG	Shelby	49 min
Aug 20, 6:11 PM CDT	Special Weather Statement	MEG	Tipton	34 min
Aug 20, 6:22 PM CDT	Special Weather Statement	MEG	Fayette	23 min
Aug 20, 6:30 PM CDT	Severe Thunderstorm Warning	MEG	Fayette, Shelby	28 min
Aug 20, 6:44 PM CDT	Special Weather Statement	MEG	Lake	46 min
Aug 19, 7:11 PM CDT	Special Weather Statement	MEG	Coahoma	34 min
Aug 20, 3:08 PM CDT	Special Weather Statement	MEG	Tunica	37 min
Aug 20, 3:20 PM CDT	Severe Thunderstorm Warning	MEG	Coahoma, Tunica	40 min
Aug 20, 4:11 PM CDT	Severe Thunderstorm Warning	MEG	Coahoma, Panola, Quitman, Tate, Tunica	49 min
Aug 20, 4:23 PM CDT	Tornado Warning	MEG	Coahoma, Panola, Quitman, Tunica	52 min
Aug 20, 5:13 PM CDT	Tornado Warning	MEG	Panola, Quitman	47 min
Aug 20, 5:37 PM CDT	Special Weather Statement	MEG	Tallahatchie	23 min
Aug 20, 5:51 PM CDT	Severe Thunderstorm Warning	MEG	Panola, Quitman, Tallahatchie	39 min
Aug 20, 5:59 PM CDT	Severe Thunderstorm Warning	MEG	Lafayette, Panola	46 min
Aug 20, 6:27 PM CDT	Severe Thunderstorm Warning	MEG	Lafayette, Panola, Quitman, Tallahatchie, Yalobusha	48 min
Aug 20, 6:30 PM CDT	Severe Thunderstorm Warning	MEG	Tunica	26 min
Aug 20, 6:34 PM CDT	Special Weather Statement	MEG	DeSoto	26 min
Aug 20, 6:49 PM CDT	Areal Flood Advisory	MEG	Lafayette, Panola	116 min
Aug 20, 6:49 PM CDT	Severe Thunderstorm Warning	MEG	Calhoun, Lafayette, Pontotoc	41 min
Aug 19, 10:41 PM CDT	Special Weather Statement	MEG	Lawrence	49 min
Aug 19, 11:29 PM CDT	Special Weather Statement	MEG	Lawrence	31 min
Aug 20, 9:42 AM CDT	Special Weather Statement	MEG	Cross, St. Francis	48 min
Aug 20, 10:27 AM CDT	Special Weather Statement	MEG	Crittenden	48 min
Aug 20, 2:07 PM CDT	Special Weather Statement	MEG	Lee	23 min
Aug 20, 3:13 PM CDT	Special Weather Statement	MEG	Randolph	32 min
Aug 20, 3:57 PM CDT	Special Weather Statement	MEG	Cross	48 min
Aug 20, 4:07 PM CDT	Special Weather Statement	MEG	Phillips	38 min
Aug 20, 4:13 PM CDT	Special Weather Statement	MEG	Clay	47 min
Aug 20, 4:24 PM CDT	Severe Thunderstorm Warning	MEG	Cross, St. Francis	51 min
Aug 20, 4:45 PM CDT	Special Weather Statement	MEG	Clay	15 min
Aug 20, 4:54 PM CDT	Severe Thunderstorm Warning	MEG	Crittenden, Lee, St. Francis	51 min
Aug 20, 5:28 PM CDT	Special Weather Statement	MEG	Clay	17 min
Aug 20, 5:30 PM CDT	Tornado Warning	MEG	Greene	34 min
Aug 20, 5:51 PM CDT	Special Weather Statement	MEG	St. Francis	39 min
Aug 20, 6:37 PM CDT	Special Weather Statement	MEG	Greene	38 min

Nearby

Severe Thunderstorm Warnings in Arkansas, 2018 Severe Thunderstorm Warnings in Tennessee, 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.