Alert archive / Tennessee / Mesoscale Discussions in 2012
Mesoscale Discussion 644
The Storm Prediction Center issued this mesoscale discussion at May 1, 2012, 12:33 PM CDT for 23 counties in Kentucky; 29 counties in Tennessee. It was in force for 117 min.
The area
The outline as issued.
The facts
- Issued
- May 1, 2012, 12:33 PM CDT (17:33 UTC)
- Expired
- May 1, 2012, 2:30 PM CDT
- In force
- 117 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 40%
All 52 counties
Adair County, KY, Allen County, KY, Barren County, KY, Butler County, KY, Casey County, KY, Clinton County, KY, Cumberland County, KY, Edmonson County, KY, Grayson County, KY, Green County, KY, Hardin County, KY, Hart County, KY, Larue County, KY, Logan County, KY, McCreary County, KY, Metcalfe County, KY, Monroe County, KY, Pulaski County, KY, Russell County, KY, Simpson County, KY, Taylor County, KY, Warren County, KY, Wayne County, KY, Bedford County, TN, Bledsoe County, TN, Cannon County, TN, Clay County, TN, Coffee County, TN, Cumberland County, TN, Davidson County, TN, DeKalb County, TN, Fentress County, TN, Franklin County, TN, Grundy County, TN, Jackson County, TN, Macon County, TN, Marshall County, TN, Moore County, TN, Overton County, TN, Pickett County, TN, Putnam County, TN, Robertson County, TN, Rutherford County, TN, Sequatchie County, TN, Smith 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), 49 km from the middle of the area, began a volume at 17:34 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, 5.6 hours before the alert went out and 51 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
- 1383 J/kg
- Mixed-layer CIN
- -44 J/kg
- Mixed-layer LCL
- 880 m above ground
- 0-6 km bulk shear
- 27 kt
- 0-1 km storm-relative helicity
- 50 m²/s²
- 0-3 km storm-relative helicity
- -1 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.3
The text
As transmitted, in the capitals the NWS used until 2016.
698
ACUS11 KWNS 011733
SWOMCD
SPC MCD 011733
KYZ000-TNZ000-011930-
MESOSCALE DISCUSSION 0644
NWS STORM PREDICTION CENTER NORMAN OK
1233 PM CDT TUE MAY 01 2012
AREAS AFFECTED...MIDDLE/EASTERN TN AND CENTRAL/EASTERN KY
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 011733Z - 011930Z
PROBABILITY OF WATCH ISSUANCE...40 PERCENT
SUMMARY...AT LEAST ISOLATED SEVERE TSTMS CAPABLE OF WIND/HAIL ARE
LIKELY TO DEVELOP/INCREASE THROUGH EARLY/MID AFTERNOON ACROSS
PORTIONS OF MIDDLE/EASTERN TN AND CENTRAL/EASTERN KY.
DISCUSSION...VISIBLE SATELLITE IMAGERY SINCE 1630Z IS INDICATIVE OF
AN INCREASING/DEEPENING CU FIELD ACROSS THE TN VALLEY...ESPECIALLY
ACROSS PORTIONS OF MIDDLE TO EASTERN TN AND SOUTH-CENTRAL
KY/NORTHEAST AL. CONTEMPORARY MODIFICATIONS TO THE 12Z NASHVILLE
OBSERVED SOUNDING CONFIRM THAT BOUNDARY LAYER CINH IS VIRTUALLY NIL
AS SURFACE TEMPERATURES HAVE CLIMBED ABOVE 80F...WITH SPC OBJECTIVE
ANALYSIS NOW INDICATIVE OF MLCAPE TO 2000-3000 J/KG.
FURTHERMORE...THE REGION IS BEING INFLUENCE BY THE SOUTHERN
PERIPHERY OF A SHORTWAVE TROUGH/MCV ACROSS THE MIDDLE MS
VALLEY...AND ITS GRAZING INFLUENCE WILL BE A FACTOR FOR INCREASING
TSTM COVERAGE/VIGOR AND SUSTAINABILITY THIS AFTERNOON. AIDED BY
RELATIVELY STRONG MID LEVEL WEST-SOUTHWESTERLY FLOW AND RESULTANT
EFFECTIVE SHEAR OF 30-35 KT...SUSTAINED MULTICELLS/SOME SUPERCELLS
WILL BE POSSIBLE WITH ASSOCIATED POTENTIAL FOR SEVERE HAIL/WIND.
..GUYER/MEAD.. 05/01/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...MRX...JKL...LMK...OHX...HUN...PAH...
LAT...LON 35248706 36818711 37878607 37058415 35628509 35088571
35248706SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 30, 8:07 PM CDT | Mesoscale Discussion | SPC | Anderson, Bath, Boone, Bourbon, Boyd, Boyle and 52 more | 53 min |
| May 1, 1:44 PM CDT | Severe Thunderstorm Watch | SPC | Adair, Allen, Anderson, Barren, Bath, Bourbon and 59 more | 6 hr |
| May 1, 2:01 PM CDT | Tornado Watch | SPC | Boone, Bracken, Campbell, Carroll, Gallatin, Grant and 8 more | 7 hr |
| May 1, 5:13 PM CDT | Mesoscale Discussion | SPC | Boyd | 62 min |
| May 1, 5:31 PM CDT | Tornado Watch | SPC | Boone, Boyd, Bracken, Campbell, Carroll, Carter and 9 more | 5 hr |
Nearby
Mesoscale Discussions in Tennessee, 2012Mesoscale Discussions in Kentucky, 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.