Alert archive / South Carolina / Mesoscale Discussions in 2012

Mesoscale Discussion 1930

September 8, 201212 counties in North Carolina; 21 counties in South Carolina

The Storm Prediction Center issued this mesoscale discussion at Sep 8, 2012, 1:14 PM EDT for 12 counties in North Carolina; 21 counties in South Carolina. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Sep 8, 2012, 1:14 PM EDT (17:14 UTC)
Expired
Sep 8, 2012, 3:15 PM EDT
In force
2 hr
Issued by
the Storm Prediction Center
Chance of a watch
40%
All 33 counties

Cabarrus County, NC, Catawba County, NC, Cleveland County, NC, Gaston County, NC, Iredell County, NC, Lincoln County, NC, Mecklenburg County, NC, Polk County, NC, Rowan County, NC, Rutherford County, NC, Stanly County, NC, Union County, NC, Abbeville County, SC, Aiken County, SC, Anderson County, SC, Calhoun County, SC, Cherokee County, SC, Chester County, SC, Edgefield County, SC, Fairfield County, SC, Greenville County, SC, Greenwood County, SC, Kershaw County, SC, Lancaster County, SC, Laurens County, SC, Lexington County, SC, Newberry County, SC, Pickens County, SC, Richland County, SC, Saluda County, SC, Spartanburg County, SC, Union County, SC, York County, SC

The radar

The Greer radar (KGSP), 62 km from the middle of the area, began a volume at 17:16 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

Greensboro/Hi Pt, NC (KGSO), launched 12:00Z, 5.2 hours before the alert went out and 206 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.

Skew-T log-pSkew-T log-p diagram, Greensboro/Hi Pt, NC at 12:00Z on 2012-09-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 305 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Greensboro/Hi Pt, NC at 12:00Z on 2012-09-08The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 68 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
305 J/kg
Mixed-layer CIN
-62 J/kg
Mixed-layer LCL
814 m above ground
0-6 km bulk shear
20 kt
0-1 km storm-relative helicity
68 m²/s²
0-3 km storm-relative helicity
44 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

914 
ACUS11 KWNS 081715
SWOMCD
SPC MCD 081714
SCZ000-NCZ000-081915-

MESOSCALE DISCUSSION 1930
NWS STORM PREDICTION CENTER NORMAN OK
1214 PM CDT SAT SEP 08 2012

AREAS AFFECTED...SWRN NC...CNTRL/WRN SC

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 081714Z - 081915Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...THE THREAT FOR SVR STORMS WILL INCREASE THIS
AFTERNOON...AND THE ISSUANCE OF A SEVERE THUNDERSTORM WATCH IS
POSSIBLE.

DISCUSSION...AS LARGE-SCALE FORCING FOR ASCENT STRENGTHENS...
SCATTERED THUNDERSTORMS WILL CONTINUE TO DEVELOP IN ADVANCE OF A
COLD FRONT CURRENTLY CROSSING THE APPALACHIANS. A LEE TROUGH...ALONG
WITH SUBTLE PRE-FRONTAL MOISTURE/THERMAL GRADIENTS...WILL SERVE AS
THE PRIMARY FOCI FOR LIFT AMIDST 1500-2500 J/KG OF UNINHIBITED
MLCAPE PER MODIFIED 12Z RAOBS. MID-LEVEL FLOW IS COMPARATIVELY
WEAKER OVER THIS REGION RELATIVE TO LOCATIONS FARTHER NORTH...THOUGH
20-30 KT OF EFFECTIVE BULK SHEAR THROUGH THE AFTERNOON MAY SUPPORT
ORGANIZED MULTICELL CLUSTERS WITH DMGG WIND GUSTS AND PERHAPS
MARGINALLY SVR HAIL.

..COHEN/THOMPSON.. 09/08/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...RAH...CAE...GSP...

LAT...LON   35148281 35938134 35708044 35108008 33698048 33418169
            34378274 35148281

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 8, 12:20 PM EDTMesoscale DiscussionSPCAlamance, Alexander, Alleghany, Caswell, Davidson, Davie and 10 more115 min
Sep 8, 1:48 PM EDTSevere Thunderstorm WatchSPCAlamance, Alexander, Anson, Cabarrus, Caswell, Catawba and 44 more7 hr
Sep 8, 3:25 PM EDTMesoscale DiscussionSPCAlamance, Alexander, Cabarrus, Caswell, Catawba, Chatham and 33 more65 min
Sep 8, 7:10 PM EDTMesoscale DiscussionSPCBeaufort, Bertie, Bladen, Chowan, Craven, Cumberland and 23 more65 min

Nearby

Mesoscale Discussions in South Carolina, 2012Mesoscale Discussions in North Carolina, 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.