Alert archive / Tennessee / Mesoscale Discussions in 2012
Mesoscale Discussion 1670
The Storm Prediction Center issued this mesoscale discussion at Aug 1, 2012, 2:52 PM EDT for 13 counties in North Carolina; 51 counties in Tennessee; 6 counties in Virginia. It was in force for 53 min.
The area
The outline as issued.
The facts
- Issued
- Aug 1, 2012, 2:52 PM EDT (18:52 UTC)
- Expired
- Aug 1, 2012, 3:45 PM EDT
- In force
- 53 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 60%
All 70 counties
Ashe County, NC, Avery County, NC, Buncombe County, NC, Cherokee County, NC, Graham County, NC, Haywood County, NC, Jackson County, NC, Macon County, NC, Madison County, NC, Mitchell County, NC, Swain County, NC, Watauga County, NC, Yancey County, NC, Anderson County, TN, Bledsoe County, TN, Blount County, TN, Bradley County, TN, Campbell County, TN, Cannon County, TN, Carter County, TN, Claiborne County, TN, Clay County, TN, Cocke County, TN, Coffee County, TN, Cumberland County, TN, DeKalb County, TN, Fentress County, TN, Grainger County, TN, Greene County, TN, Grundy County, TN, Hamblen County, TN, Hamilton County, TN, Hancock County, TN, Hawkins County, TN, Jackson County, TN, Jefferson County, TN, Johnson County, TN, Knox County, TN, Loudon County, TN, McMinn County, TN, Meigs County, TN, Monroe County, TN, Morgan County, TN, Overton County, TN, Pickett County, TN, Polk County, TN, Putnam County, TN, Rhea County, TN, Roane County, TN, Rutherford County, TN, Scott County, TN, Sequatchie County, TN, Sevier County, TN, Smith County, TN, Sullivan County, TN, Sumner County, TN, Trousdale County, TN, Unicoi County, TN, Union County, TN, Van Buren County, TN, Warren County, TN, Washington County, TN, White County, TN, Wilson County, TN, City of Bristol, VA, Lee County, VA, Russell County, VA, Scott County, VA, Smyth County, VA, Washington County, VA
The radar
The Knoxville radar (KMRX), 19 km from the middle of the area, began a volume at 18:54 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, 6.9 hours before the alert went out and 268 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
- 1698 J/kg
- Mixed-layer CIN
- -98 J/kg
- Mixed-layer LCL
- 1123 m above ground
- 0-6 km bulk shear
- 31 kt
- 0-1 km storm-relative helicity
- 71 m²/s²
- 0-3 km storm-relative helicity
- 114 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.7
The text
As transmitted, in the capitals the NWS used until 2016.
796
ACUS11 KWNS 011853
SWOMCD
SPC MCD 011852
VAZ000-NCZ000-TNZ000-011945-
MESOSCALE DISCUSSION 1670
NWS STORM PREDICTION CENTER NORMAN OK
0152 PM CDT WED AUG 01 2012
AREAS AFFECTED...MIDDLE/ERN TN...WRN NC...FAR SWRN VA
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 011852Z - 011945Z
PROBABILITY OF WATCH ISSUANCE...60 PERCENT
SUMMARY...TSTM COVERAGE IS EXPECTED TO INCREASE OVER PARTS OF MIDDLE
TN AND THE CNTRL APPALACHIANS THIS AFTERNOON. A FEW CLUSTERS MAY
EVENTUALLY DEVELOP...POSING A RISK FOR STRONG-SVR WIND GUSTS AND
HAIL. A WW MAY NEED TO BE CONSIDERED. PARTS OF THIS REGION WILL ALSO
BE UPGRADED TO A SLIGHT RISK AT 20Z.
DISCUSSION...VISIBLE SATELLITE LOOP SHOWS BUILDING CU/TOWERING CU
FIELD NEAR THE TN/KY BORDER...AND ACROSS PORTIONS OF THE HIGHER
TERRAIN OF FAR SWRN VA...AS STRONG HEATING HAS ERODED MOST CINH.
THREE MESOSCALE FEATURES OF INTEREST ARE APPARENT...INCLUDING 1) A
WEAK COLD FRONT EXTENDING ACROSS SRN KY...2) A LINE OF CU ORIENTED
SSW TO NNE ACROSS ERN TN ASSOCIATED WITH A DIFFERENTIAL HEATING ZONE
FROM EARLIER TODAY AND WEAK UPSLOPE FLOW...AND 3) A WEAK UPPER
IMPULSE NOTED ON WATER VAPOR IMAGERY ENTERING ERN KY. EACH OF THESE
FEATURES SHOULD PROVIDE A FOCUS FOR ADDITIONAL TSTM DEVELOPMENT OVER
THE NEXT 1-2 HRS.
RICH BOUNDARY LAYER MOISTURE /WITH SFC DEWPOINTS IN THE UPPER
60S-LOWER 70S/ IS YIELDING MLCAPE VALUES OF 1500-2500 J/KG...DESPITE
RELATIVELY WARM MIDLEVEL TEMPERATURE PROFILES.
ADDITIONALLY...MODERATE MIDLEVEL FLOW /30-35 KTS/ WILL BE SUPPORTIVE
FOR ONE OR MORE ORGANIZED MULTICELL CLUSTERS TO EVOLVE AS TSTMS
CONSOLIDATE/MERGE...PROPAGATING TOWARDS THE SSE. THESE CONDITIONS
WILL SUPPORT A THREAT FOR DMGG WINDS AND LARGE HAIL...AND MAY
REQUIRE ISSUANCE OF A WW SHOULD CONVECTIVE TRENDS CONTINUE TO
INCREASE.
..ROGERS/CARBIN.. 08/01/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...RNK...RLX...GSP...MRX...OHX...HUN...
LAT...LON 36538117 35858204 35258295 35028401 35048533 35418624
36028656 36528649 36578500 36528378 36568345 36668328
36878286 37018207 36998140 36538117SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 1, 3:40 PM EDT | Severe Thunderstorm Watch | SPC | Anderson, Benton, Bledsoe, Blount, Bradley, Campbell and 50 more | 7 hr |
| Aug 1, 4:02 PM EDT | Severe Thunderstorm Watch | SPC | Hardeman, Hardin, McNairy | 6 hr |
Nearby
Mesoscale Discussions in Tennessee, 2012Mesoscale Discussions in North Carolina, 2012Mesoscale Discussions in Virginia, 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.