Alert archive / Kentucky / Mesoscale Discussions in 2021
Mesoscale Discussion 258
The Storm Prediction Center issued this mesoscale discussion at Mar 25, 2021, 2:33 PM CDT for 5 states. It was in force for 117 min.
The area
The outline as issued.
The facts
- Issued
- Mar 25, 2021, 2:33 PM CDT (19:33 UTC)
- Expired
- Mar 25, 2021, 4:30 PM CDT
- In force
- 117 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...tornado watch likely
- Chance of a watch
- 80%
All 61 counties
Alexander County, IL, Edwards County, IL, Franklin County, IL, Gallatin County, IL, Hamilton County, IL, Hardin County, IL, Jackson County, IL, Jefferson County, IL, Johnson County, IL, Lawrence County, IL, Massac County, IL, Perry County, IL, Pope County, IL, Pulaski County, IL, Richland County, IL, Saline County, IL, Union County, IL, Wabash County, IL, Wayne County, IL, White County, IL, Williamson County, IL, Dubois County, IN, Gibson County, IN, Knox County, IN, Pike County, IN, Posey County, IN, Spencer County, IN, Vanderburgh County, IN, Warrick County, IN, Ballard County, KY, Caldwell County, KY, Calloway County, KY, Carlisle County, KY, Christian County, KY, Crittenden County, KY, Daviess County, KY, Fulton County, KY, Graves County, KY, Hancock County, KY, Henderson County, KY, Hickman County, KY, Hopkins County, KY, Livingston County, KY, Lyon County, KY, Marshall County, KY, McCracken County, KY, McLean County, KY, Muhlenberg County, KY, Ohio County, KY, Trigg County, KY, Union County, KY, Webster County, KY, Cape Girardeau County, MO, Mississippi County, MO, New Madrid County, MO, Scott County, MO, Dyer County, TN, Henry County, TN, Lake County, TN, Obion County, TN, Weakley County, TN
The radar
The Paducah radar (KPAH), 42 km from the middle of the area, began a volume at 19:35 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
Nashville Metro, TN (KBNA), launched 12:00Z, 7.6 hours before the alert went out and 208 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
- 60 J/kg
- Mixed-layer CIN
- -88 J/kg
- Mixed-layer LCL
- 753 m above ground
- 0-6 km bulk shear
- 57 kt
- 0-1 km storm-relative helicity
- 168 m²/s²
- 0-3 km storm-relative helicity
- 113 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
851
ACUS11 KWNS 251933
SWOMCD
SPC MCD 251933
INZ000-KYZ000-TNZ000-ILZ000-MOZ000-252130-
Mesoscale Discussion 0258
NWS Storm Prediction Center Norman OK
0233 PM CDT Thu Mar 25 2021
Areas affected...The mid-Mississippi River Valley and lower Ohio
River Valley Region
Concerning...Severe potential...Tornado Watch likely
Valid 251933Z - 252130Z
Probability of Watch Issuance...80 percent
SUMMARY...A tornado watch is likely in the coming hours as a surface
low and associated warm front continue to lift northward through the
late afternoon.
DISCUSSION...Surface observations over the past couple of hours have
shown 2-3 mb surface pressure falls over northeast AR into the lower
OH River Valley region. The surface low located over northeast AR
continues to consolidate and is expected to deepen further as it
lifts to the north/northeast. As this occurs, an associated surface
warm front will lift to the north and allow a higher theta-e air
mass (noted by temperatures and dewpoints in the 60s) to overspread
the mid-MS River Valley and lower OH River Valley regions and allow
MLCAPE to increase into the 500-1000 J/kg range. Storms are forecast
to develop along the surface warm front and surface trough in the
vicinity of the low, and southwesterly 60-70 knots of effective bulk
shear will help support discrete to semi-discrete storm modes. Along
with a hail/wind threat, backed low-level winds within the open warm
sector will support ESRH values on the order of 300 m2/s2 and a
tornado threat with any discrete convection that can develop. Recent
guidance suggests storm initiation within this region may occur
within the 22-00 UTC time frame. A tornado watch will likely be
needed in the coming hours to address this concern.
..Moore/Hart.. 03/25/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LMK...OHX...IND...PAH...ILX...MEG...LSX...
LAT...LON 36498774 36148863 35988936 36238974 36718989 37438983
38008958 38438912 38778824 38788726 38348672 37528679
37008706 36498774SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 25, 3:48 PM CDT | Tornado Watch | SPC | Alexander, Edwards, Franklin, Gallatin, Hamilton, Hardin and 13 more | 7 hr |
| Mar 25, 5:52 PM CDT | Mesoscale Discussion | SPC | Allen, Barren, Breckinridge, Butler, Caldwell, Calloway and 23 more | 83 min |
| Mar 25, 9:02 AM CDT | Mesoscale Discussion | SPC | Franklin, Giles, Lawrence, Lincoln, Marion, Moore and 1 more | 118 min |
| Mar 25, 10:12 AM CDT | Mesoscale Discussion | SPC | Franklin, Giles, Lincoln, Marion, Moore | 3 hr |
| Mar 25, 11:26 AM CDT | Tornado Watch | SPC | Franklin, Giles, Lawrence, Lincoln, Moore, Wayne | 9 hr |
| Mar 25, 2:29 PM CDT | Mesoscale Discussion | SPC | Bedford, Benton, Cannon, Cheatham, Chester, Davidson and 16 more | 2 hr |
| Mar 25, 4:31 PM CDT | Mesoscale Discussion | SPC | Bledsoe, Blount, Bradley, Hamilton, Loudon, McMinn and 5 more | 119 min |
Nearby
Mesoscale Discussions in Kentucky, 2021Mesoscale Discussions in Illinois, 2021Mesoscale Discussions in Indiana, 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.