Alert archive / Tennessee / Mesoscale Discussions in 2012
Mesoscale Discussion 2172
The Storm Prediction Center issued this mesoscale discussion at Dec 17, 2012, 1:24 PM CST for Lauderdale County, Alabama; 4 counties in Mississippi; 18 counties in Tennessee. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Dec 17, 2012, 1:24 PM CST (19:24 UTC)
- Expired
- Dec 17, 2012, 3:30 PM CST
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 20%
All 23 counties
Lauderdale County, AL, Alcorn County, MS, Benton County, MS, Tippah County, MS, Tishomingo County, MS, Bedford County, TN, Chester County, TN, Coffee County, TN, Decatur County, TN, Giles County, TN, Grundy County, TN, Hardeman County, TN, Hardin County, TN, Lawrence County, TN, Lewis County, TN, Lincoln County, TN, Marshall County, TN, Maury County, TN, McNairy County, TN, Moore County, TN, Perry County, TN, Warren County, TN, Wayne County, TN
The radar
The Nashville radar (KOHX), 153 km from the middle of the area, began a volume at 19:26 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 12:00Z, 7.4 hours before the alert went out and 142 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
- 100 J/kg
- Mixed-layer CIN
- -5 J/kg
- Mixed-layer LCL
- 447 m above ground
- 0-6 km bulk shear
- 78 kt
- 0-1 km storm-relative helicity
- 91 m²/s²
- 0-3 km storm-relative helicity
- 185 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
725
ACUS11 KWNS 171925
SWOMCD
SPC MCD 171924
TNZ000-ALZ000-MSZ000-172130-
MESOSCALE DISCUSSION 2172
NWS STORM PREDICTION CENTER NORMAN OK
0124 PM CST MON DEC 17 2012
AREAS AFFECTED...PARTS OF SRN TN...NRN MS...NRN AL
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 171924Z - 172130Z
PROBABILITY OF WATCH ISSUANCE...20 PERCENT
SUMMARY...AN ISOLATED SVR THREAT MAY OCCUR SOUTH OF WW 683 THIS
AFTERNOON. WITH ANY SVR THREAT EXPECTED TO BE MARGINAL/SPORADIC...
THE ISSUANCE OF A NEW WW IS UNLIKELY...THOUGH WW 683 MAY BE EXPANDED
SWD ACROSS PARTS OF MIDDLE TN.
DISCUSSION...WITH THE GLANCING INFLUENCE OF A SHORTWAVE IMPULSE THAT
IS CURRENTLY TRACKING ACROSS THE OH VALLEY...ISOLATED STORMS MAY
CONTINUE DEVELOPING SOUTH OF WW 683. MARGINAL INSTABILITY COMBINED
WITH STRONG DEEP SHEAR MAY SUPPORT OCCASIONALLY ORGANIZED...
LOW-TOPPED CONVECTIVE STRUCTURES. MARGINALLY SVR HAIL/WIND CANNOT BE
RULED OUT WITH THE MOST INTENSE STORMS...THOUGH THE LIMITED
INSTABILITY AND LACK OF STRONGER DEEP ASCENT WILL MITIGATE THE SVR
THREAT. REGARDLESS...SHOULD A MORE SUBSTANTIAL THREAT APPEAR TO
EVOLVE ACROSS SRN MIDDLE TN -- IN CLOSER PROXIMITY TO THE STRONGER
ASCENT -- WW 683 MAY BE EXPANDED SWD.
..COHEN/CORFIDI.. 12/17/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...OHX...HUN...MEG...
LAT...LON 35018956 35338905 35708826 35768686 35748588 35738554
35298575 34788711 34668826 34728924 35018956SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 17, 4:16 AM CST | Mesoscale Discussion | SPC | Baldwin, Escambia, Mobile | 119 min |
| Dec 17, 10:49 AM CST | Mesoscale Discussion | SPC | Houston | 116 min |
| Dec 17, 11:03 AM CST | Mesoscale Discussion | SPC | Benton, Cannon, Cheatham, Clay, Davidson, DeKalb and 19 more | 117 min |
| Dec 17, 11:26 AM CST | Severe Thunderstorm Watch | SPC | Benton, Cannon, Cheatham, Clay, Cumberland, Davidson and 22 more | 6 hr |
| Dec 17, 12:58 PM CST | Mesoscale Discussion | SPC | Benton, Cannon, Cheatham, Clay, Cumberland, Davidson and 21 more | 92 min |
| Dec 17, 3:42 PM CST | Mesoscale Discussion | SPC | Benton, Cannon, Cheatham, Clay, Davidson, DeKalb and 20 more | 93 min |
Nearby
Mesoscale Discussions in Tennessee, 2012Mesoscale Discussions in Mississippi, 2012Mesoscale Discussions in Alabama, 2012Every mesoscale discussion in 2012
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.