Alert archive / Mississippi / Mesoscale Discussions in 2021
Mesoscale Discussion 1867
The Storm Prediction Center issued this mesoscale discussion at Oct 15, 2021, 5:06 PM CDT for 11 counties in Mississippi; 10 counties in Tennessee. It was in force for 114 min.
The area
The outline as issued.
The facts
- Issued
- Oct 15, 2021, 5:06 PM CDT (22:06 UTC)
- Expired
- Oct 15, 2021, 7:00 PM CDT
- In force
- 114 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 60%
All 21 counties
Alcorn County, MS, Benton County, MS, DeSoto County, MS, Lafayette County, MS, Marshall County, MS, Panola County, MS, Prentiss County, MS, Tate County, MS, Tippah County, MS, Tunica County, MS, Union County, MS, Chester County, TN, Decatur County, TN, Fayette County, TN, Hardeman County, TN, Hardin County, TN, Haywood County, TN, Henderson County, TN, Madison County, TN, McNairy County, TN, Shelby County, TN
The radar
The Memphis radar (KNQA), 64 km from the middle of the area, began a volume at 22:07 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, 10.1 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.
- 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.
131
ACUS11 KWNS 152207
SWOMCD
SPC MCD 152206
ALZ000-TNZ000-MSZ000-ARZ000-160000-
Mesoscale Discussion 1867
NWS Storm Prediction Center Norman OK
0506 PM CDT Fri Oct 15 2021
Areas affected...northern MS...southwest TN
Concerning...Severe potential...Watch possible
Valid 152206Z - 160000Z
Probability of Watch Issuance...60 percent
SUMMARY...Forecast soundings show hodographs enlarging over the next
2-3 hours between 5pm to 7-8pm. An isolated risk for a tornado may
accompany the stronger storms. The threat for damaging gusts will
likely concentrate near the RFD of any supercells or downdraft
surges with bowing segments.
DISCUSSION...Radar mosaic shows a linear cluster of storms over
eastern AR expected to cross the MS River over the next 1-2 hours.
Surface temperatures have warmed into the lower 80s near Memphis and
cooler rain-cooled air (low to mid 70s F) is located over northern
MS.
KNQA (Memphis, TN) WSR-88D VAD shows a largely unidirectional
southwesterly wind profile with flow increasing with height to
around 60 kt at 6 km AGL. Both RAP and NAM forecast soundings
indicate the hodograph size will increase over the next few hours as
flow strengthens in the boundary layer and 700-mb flow increases
from 25 kt as of 5pm CDT to 35-40 kt by 7-8pm CDT. As large-scale
forcing for ascent strengthens with the approach of the mid-upper
trough, expecting a severe risk to continue to the east and
southeast of severe thunderstorm watch #527 (into parts of northern
MS). Damaging gusts will be the primary concern with the stronger
storms but a tornado threat may increase coincident with the
hodograph enlargement.
..Smith/Guyer.. 10/15/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OHX...HUN...MEG...
LAT...LON 34779056 35718951 35688801 34918807 34388868 34289033
34779056SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Oct 15, 11:14 AM CDT | Mesoscale Discussion | SPC | Coahoma, DeSoto, Tunica | 3 hr |
| Oct 15, 12:28 PM CDT | Severe Thunderstorm Watch | SPC | DeSoto, Tunica | 9 hr |
| Oct 15, 2:52 PM CDT | Mesoscale Discussion | SPC | DeSoto, Tunica | 113 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 Mississippi, 2021Mesoscale Discussions in Tennessee, 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.