Alert archive / Arkansas / Mesoscale Discussions in 2021
Mesoscale Discussion 1863
The Storm Prediction Center issued this mesoscale discussion at Oct 15, 2021, 11:14 AM CDT for 6 states. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Oct 15, 2021, 11:14 AM CDT (16:14 UTC)
- Expired
- Oct 15, 2021, 1:45 PM CDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch likely
- Chance of a watch
- 80%
All 46 counties
Arkansas County, AR, Clay County, AR, Craighead County, AR, Crittenden County, AR, Cross County, AR, Faulkner County, AR, Grant County, AR, Greene County, AR, Jackson County, AR, Jefferson County, AR, Lee County, AR, Lonoke County, AR, Mississippi County, AR, Monroe County, AR, Phillips County, AR, Poinsett County, AR, Prairie County, AR, Pulaski County, AR, Saline County, AR, St. Francis County, AR, White County, AR, Woodruff County, AR, Alexander County, IL, Massac County, IL, Pulaski County, IL, Ballard County, KY, Carlisle County, KY, Fulton County, KY, Graves County, KY, Hickman County, KY, McCracken County, KY, Dunklin County, MO, Mississippi County, MO, New Madrid County, MO, Pemiscot County, MO, Scott County, MO, Stoddard County, MO, Coahoma County, MS, DeSoto County, MS, Tunica County, MS, Dyer County, TN, Lake County, TN, Lauderdale County, TN, Obion County, TN, Shelby County, TN, Tipton County, TN
The radar
The Memphis radar (KNQA), 94 km from the middle of the area, began a volume at 16:17 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 watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Little Rock, AR (KLZK), launched 12:00Z, 4.2 hours before the alert went out and 116 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.
- Mixed-layer CAPE
- 567 J/kg
- Mixed-layer CIN
- -16 J/kg
- Mixed-layer LCL
- 671 m above ground
- 0-6 km bulk shear
- 47 kt
- 0-1 km storm-relative helicity
- 69 m²/s²
- 0-3 km storm-relative helicity
- 55 m²/s²
- Significant tornado parameter
- 0.2
- Supercell composite
- 1.5
The text
As transmitted.
959
ACUS11 KWNS 151615
SWOMCD
SPC MCD 151614
KYZ000-ILZ000-TNZ000-MOZ000-ARZ000-MSZ000-151845-
Mesoscale Discussion 1863
NWS Storm Prediction Center Norman OK
1114 AM CDT Fri Oct 15 2021
Areas affected...central and northeast Arkansas into far western
Kentucky and Tennessee
Concerning...Severe potential...Watch likely
Valid 151614Z - 151845Z
Probability of Watch Issuance...80 percent
SUMMARY...Scattered storms, some possibly severe producing damaging
gusts, are expected to develop over the next few hours from Arkansas
into western Kentucky and Tennessee.
DISCUSSION...Surface analysis shows a cold front from northern AR
into southern IL and IN, with 68-72 F dewpoints ahead of it. Gradual
height falls will continue over the region as the shortwave trough
moves toward the MS Valley, as pockets of heating aid
destabilization.
Objective analysis and modified forecast sounding indicate around
1000 J/kg MLCAPE over AR, with lesser values farther northeast. The
12Z LZK sounding shows a prominent midlevel inversion, which is
lessening instability. The SGF and ILX soundings also show this
midlevel warm layer.
Despite the marginal instability, strong deep-layer shear is in
place, resulting in primarily long, straight hodographs. Lift along
the front will prove sufficient to support increasing storm
coverage, and forward-tilted storms with motions over 35 kt will
lead to favorable storm-relative inflow. As such, at least a few
severe cells and/or bows are expected, producing damaging wind
gusts. Hail may also occur, though not particularly large due to the
limited instability.
..Jewell/Grams.. 10/15/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...PAH...MEG...JAN...LZK...
LAT...LON 35099280 35419210 35759142 36499056 36898994 37368903
37308864 36958847 36468859 34888994 34219049 33949123
33989237 34229283 34689289 35099280SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Oct 15, 4:12 AM CDT | Mesoscale Discussion | SPC | Crawford, Franklin, Johnson, Madison, Newton, Washington | 93 min |
| Oct 15, 12:28 PM CDT | Severe Thunderstorm Watch | SPC | Arkansas, Clark, Clay, Cleburne, Cleveland, Conway and 33 more | 9 hr |
| Oct 15, 2:52 PM CDT | Mesoscale Discussion | SPC | Arkansas, Clark, Craighead, Crittenden, Cross, Dallas and 19 more | 113 min |
| Oct 15, 5:06 PM CDT | Mesoscale Discussion | SPC | Alcorn, Benton, DeSoto, Lafayette, Marshall, Panola and 5 more | 114 min |
| Oct 15, 6:05 PM CDT | Severe Thunderstorm Watch | SPC | Alcorn, Benton, Coahoma, Itawamba, Lafayette, Lee and 9 more | 4 hr |
Nearby
Mesoscale Discussions in Arkansas, 2021Mesoscale Discussions in Kentucky, 2021Mesoscale Discussions in Missouri, 2021Every mesoscale discussion 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.