Alert archive / Tennessee / Mesoscale Discussions in 2012
Mesoscale Discussion 1509
The Storm Prediction Center issued this mesoscale discussion at Jul 19, 2012, 7:42 PM EDT for 45 counties in Tennessee. It was in force for 93 min.
The area
The outline as issued.
The facts
- Issued
- Jul 19, 2012, 7:42 PM EDT (23:42 UTC)
- Expired
- Jul 19, 2012, 9:15 PM EDT
- In force
- 93 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 40%
All 45 counties
Anderson County, TN, Bedford County, TN, Benton County, TN, Bledsoe County, TN, Campbell County, TN, Cannon County, TN, Cheatham County, TN, Clay County, TN, Coffee County, TN, Cumberland County, TN, Davidson County, TN, DeKalb County, TN, Dickson County, TN, Fentress County, TN, Grundy County, TN, Hickman County, TN, Houston County, TN, Humphreys County, TN, Jackson County, TN, Lewis County, TN, Macon County, TN, Marshall County, TN, Maury County, TN, Montgomery County, TN, Moore County, TN, Morgan County, TN, Overton County, TN, Perry County, TN, Pickett County, TN, Putnam County, TN, Rhea County, TN, Roane County, TN, Robertson County, TN, Rutherford County, TN, Scott County, TN, Sequatchie County, TN, Smith County, TN, Stewart County, TN, Sumner County, TN, Trousdale County, TN, Van Buren County, TN, Warren County, TN, White County, TN, Williamson County, TN, Wilson County, TN
The radar
The Nashville radar (KOHX), 43 km from the middle of the area, began a volume at 23:43 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, 11.7 hours before the alert went out and 40 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
- 327 J/kg
- Mixed-layer CIN
- -175 J/kg
- Mixed-layer LCL
- 1094 m above ground
- 0-6 km bulk shear
- 21 kt
- 0-1 km storm-relative helicity
- 91 m²/s²
- 0-3 km storm-relative helicity
- 98 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.5
The text
As transmitted, in the capitals the NWS used until 2016.
786
ACUS11 KWNS 192342
SWOMCD
SPC MCD 192342
TNZ000-KYZ000-200115-
MESOSCALE DISCUSSION 1509
NWS STORM PREDICTION CENTER NORMAN OK
0642 PM CDT THU JUL 19 2012
AREAS AFFECTED...MIDDLE TN
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 192342Z - 200115Z
PROBABILITY OF WATCH ISSUANCE...40 PERCENT
SUMMARY...STRONG TO SEVERE STORMS ARE POSSIBLE THIS EVENING ACROSS
MIDDLE TN. CONVECTIVE TRENDS WILL BE MONITORED FOR CONTINUED STORM
ORGANIZATION AS STORMS MOVE INTO N-CNTRL TN FROM SW/S-CNTRL KY. A WW
MAY BE NEEDED IN THE NEXT HOUR DEPENDING ON TRENDS. STRONG WIND
GUSTS ARE THE MAIN THREAT WITH THESE STORMS.
DISCUSSION...AREA IS BEING MONITORED FOR POTENTIAL SEVERE WW. STRONG
TO SEVERE STORMS MOVING ACROSS SW/S-CNTRL KY SHOULD MOVE INTO
N-CNTRL TN IN THE NEXT COUPLE OF HOURS. STRONG INSTABILITY OVER THE
REGION /MLCAPE GREATER THAN 2500 J/KG/ SHOULD HELP COMPENSATE FOR
RATHER WEAK DEEP LAYER FLOW AND ONLY MARGINAL MIDLEVEL LAPSE RATES
TO LEAD TO AT LEAST AN ISOLATED SEVERE THREAT. HOWEVER...IT IS
UNCLEAR AT THIS POINT IF STORMS WILL WEAKEN/BECOME INCREASINGLY
ELEVATED WITH LOSS OF DAYTIME HEATING. THEREFORE...THREAT COULD BE
SHORT-LIVED ACROSS N-CNTRL TN WITH A WEAKENING TREND THEREAFTER OVER
MIDDLE TN. THE SAME PHILOSOPHY HOLDS TRUE FOR CONVECTION FURTHER NE
NEAR FRANKFORT AND TRENDS WILL NEED TO BE MONITORED FOR CONTINUED
ORGANIZATION. A WW MAY BE NEEDED WITHIN THE NEXT HOUR OR SO.
..LEITMAN/CARBIN.. 07/19/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...MRX...LMK...OHX...HUN...PAH...MEG...
LAT...LON 36668780 36598499 36588377 36088416 35568469 35368540
35248687 35418806 36118817 36668780SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 19, 2:20 PM EDT | Mesoscale Discussion | SPC | Hancock, Hawkins, Sullivan | 85 min |
| Jul 19, 7:17 PM EDT | Mesoscale Discussion | SPC | Claiborne, Clay, Hancock, Pickett, Sullivan | 88 min |
Nearby
Mesoscale Discussions in Tennessee, 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.