Alert archive / Tennessee / Mesoscale Discussions in 2017
Mesoscale Discussion 1239
The Storm Prediction Center issued this mesoscale discussion at Jul 5, 2017, 9:22 PM CDT for 21 counties in Tennessee. It was in force for 53 min.
The area
The outline as issued.
The facts
- Issued
- Jul 5, 2017, 9:22 PM CDT (02:22 UTC)
- Expired
- Jul 5, 2017, 10:15 PM CDT
- In force
- 53 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 5%
All 21 counties
Bedford County, TN, Cheatham County, TN, Davidson County, TN, Dickson County, TN, Giles County, TN, Hickman County, TN, Houston County, TN, Humphreys County, TN, Lawrence County, TN, Lewis County, TN, Marshall County, TN, Maury County, TN, Montgomery County, TN, Perry County, TN, Robertson County, TN, Rutherford County, TN, Sumner County, TN, Trousdale County, TN, Wayne County, TN, Williamson County, TN, Wilson County, TN
The radar
The Nashville radar (KOHX), 83 km from the middle of the area, began a volume at 02:24 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, 2.4 hours before the alert went out and 72 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
- 487 J/kg
- Mixed-layer CIN
- -66 J/kg
- Mixed-layer LCL
- 889 m above ground
- 0-6 km bulk shear
- 33 kt
- 0-1 km storm-relative helicity
- 34 m²/s²
- 0-3 km storm-relative helicity
- 75 m²/s²
- Significant tornado parameter
- 0.1
- Supercell composite
- 1.3
The text
As transmitted.
397
ACUS11 KWNS 060223
SWOMCD
SPC MCD 060222
TNZ000-060315-
Mesoscale Discussion 1239
NWS Storm Prediction Center Norman OK
0922 PM CDT Wed Jul 05 2017
Areas affected...Portions of middle Tennessee
Concerning...Severe potential...Watch unlikely
Valid 060222Z - 060315Z
Probability of Watch Issuance...5 percent
SUMMARY...A small complex of strong/severe thunderstorms approaching
Nashville will likely maintain a damaging wind threat over the next
1-2 hours, before weakening later this evening. Watch issuance is
not expected.
DISCUSSION...Regional WSR-88D data depict a bowing complex of
thunderstorms progressing east towards Nashville this evening. Ahead
of this line, backed surface winds are modestly enhancing
storm-relative inflow, such that the line is generally maintaining
its vigor. Furthermore, adequate low-level shear (noted from recent
BNA VWP data) has supported the occasional development of
line-embedded vortices, also allowing the line to maintain its
overall organization. In turn, damaging gusts will remain possible
over the next hour or so; thereafter, increasing convective
inhibition should slow parcel ascent sufficiently to weaken the
line. Therefore, watch issuance is not anticipated.
..Picca/Thompson.. 07/06/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OHX...HUN...MEG...
LAT...LON 35418817 36588769 36628628 36228602 35338631 35148713
35178806 35418817SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 6, 12:15 PM CDT | Mesoscale Discussion | SPC | Anderson, Blount, Bradley, Campbell, Claiborne, Cocke and 16 more | 60 min |
| Jul 6, 3:52 PM CDT | Mesoscale Discussion | SPC | Anderson, Bedford, Bledsoe, Campbell, Cannon, Clay and 22 more | 113 min |
Nearby
Mesoscale Discussions in Tennessee, 2017Every mesoscale discussion in 2017
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.