Alert archive / Kentucky / Mesoscale Discussions in 2021
Mesoscale Discussion 460
The Storm Prediction Center issued this mesoscale discussion at Apr 28, 2021, 7:25 PM CDT for 6 counties in Kentucky; Henry County, Houston County, Stewart County, Tennessee. It was in force for 65 min.
The area
The outline as issued.
The facts
- Issued
- Apr 28, 2021, 7:25 PM CDT (00:25 UTC)
- Expired
- Apr 28, 2021, 8:30 PM CDT
- In force
- 65 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 118
Counties Caldwell County, KY, Calloway County, KY, Christian County, KY, Lyon County, KY, Marshall County, KY, Trigg County, KY, Henry County, TN, Houston County, TN, Stewart County, TN
The radar
The Ft Campbell radar (KHPX), 63 km from the middle of the area, began a volume at 00:26 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 nearest sounding before it
Nashville Metro, TN (KBNA), launched 00:00Z, 0.4 hours before the alert went out and 138 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
- 389 J/kg
- Mixed-layer CIN
- -49 J/kg
- Mixed-layer LCL
- 925 m above ground
- 0-6 km bulk shear
- 49 kt
- 0-1 km storm-relative helicity
- 147 m²/s²
- 0-3 km storm-relative helicity
- 153 m²/s²
- Significant tornado parameter
- 0.4
- Supercell composite
- 1.9
The text
As transmitted.
252
ACUS11 KWNS 290025
SWOMCD
SPC MCD 290025
KYZ000-TNZ000-290130-
Mesoscale Discussion 0460
NWS Storm Prediction Center Norman OK
0725 PM CDT Wed Apr 28 2021
Areas affected...Western Kentucky and far Northwestern Tennessee
Concerning...Severe Thunderstorm Watch 118...
Valid 290025Z - 290130Z
The severe weather threat for Severe Thunderstorm Watch 118
continues.
SUMMARY...The severe threat has begun to diminish across most of WW
118, but an isolated cell across northwest Tennessee will continue
to support a severe threat through at least 01 UTC.
DISCUSSION...Recent satellite and radar trends have shown a gradual
weakening of the convective line within WW 118 across western KY
over the past 1-2 hours. The main severe threat has now become
primarily limited to a discrete supercell that has emerged on the
southern flank of the line and along the weak surface baroclinic
zone in northwest TN. This cell has exhibited signs of low-level
rotation, and recent observations from the KHPX VWP show 150 m2/s2
0-1 km SRH remains in place ahead of the storm. Because of this, a
severe hail/wind risk will persist at least through 01 UTC before
diurnal cooling begins to increase inhibition. Additionally, a brief
tornado will remain possible in the near-term given the
environmental low-level shear. To the north of this supercell, a
weak MCV has had occasional updraft pulses, but these have largely
been transient and have posed minimal severe risk. While an instance
of damaging wind remains possible, the severe potential will
continue to decrease as this feature moves into a more stable air
mass.
..Moore.. 04/29/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OHX...PAH...MEG...
LAT...LON 36428874 36718855 37148831 37338780 37248736 36998718
36678722 36438747 36248774 36198816 36258853 36428874SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 29, 3:14 AM CDT | Mesoscale Discussion | SPC | Ballard, Caldwell, Calloway, Carlisle, Crittenden, Fulton and 8 more | 3 hr |
Nearby
Mesoscale Discussions in Kentucky, 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.