Alert archive / Georgia / Mesoscale Discussions in 2012
Mesoscale Discussion 1955
The Storm Prediction Center issued this mesoscale discussion at Sep 18, 2012, 12:23 AM EDT for 23 counties in Georgia; 20 counties in North Carolina; 19 counties in South Carolina. It was in force for 97 min.
The area
The outline as issued.
The facts
- Issued
- Sep 18, 2012, 12:23 AM EDT (04:23 UTC)
- Expired
- Sep 18, 2012, 2:00 AM EDT
- In force
- 97 min
- Issued by
- the Storm Prediction Center
All 62 counties
Burke County, GA, Candler County, GA, Columbia County, GA, Elbert County, GA, Emanuel County, GA, Glascock County, GA, Hancock County, GA, Hart County, GA, Jefferson County, GA, Jenkins County, GA, Johnson County, GA, Laurens County, GA, Lincoln County, GA, McDuffie County, GA, Montgomery County, GA, Oglethorpe County, GA, Richmond County, GA, Taliaferro County, GA, Toombs County, GA, Treutlen County, GA, Warren County, GA, Washington County, GA, Wilkes County, GA, Alexander County, NC, Buncombe County, NC, Burke County, NC, Cabarrus County, NC, Caldwell County, NC, Catawba County, NC, Cleveland County, NC, Davie County, NC, Gaston County, NC, Henderson County, NC, Iredell County, NC, Lincoln County, NC, McDowell County, NC, Mecklenburg County, NC, Polk County, NC, Rowan County, NC, Rutherford County, NC, Transylvania County, NC, Wilkes County, NC, Yadkin County, NC, Abbeville County, SC, Aiken County, SC, Anderson County, SC, Cherokee County, SC, Chester County, SC, Edgefield County, SC, Fairfield County, SC, Greenville County, SC, Greenwood County, SC, Laurens County, SC, Lexington County, SC, McCormick County, SC, Newberry County, SC, Oconee County, SC, Pickens County, SC, Saluda County, SC, Spartanburg County, SC, Union County, SC, York County, SC
The radar
The Greer radar (KGSP), 77 km from the middle of the area, began a volume at 04:25 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
Charleston AFB, SC (KCHS), launched 00:00Z, 4.4 hours before the alert went out and 235 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
- 434 J/kg
- Mixed-layer CIN
- -23 J/kg
- Mixed-layer LCL
- 846 m above ground
- 0-6 km bulk shear
- 21 kt
- 0-1 km storm-relative helicity
- 106 m²/s²
- 0-3 km storm-relative helicity
- 108 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.9
The text
As transmitted, in the capitals the NWS used until 2016.
534
ACUS11 KWNS 180424
SWOMCD
SPC MCD 180423
NCZ000-SCZ000-GAZ000-180600-
MESOSCALE DISCUSSION 1955
NWS STORM PREDICTION CENTER NORMAN OK
1123 PM CDT MON SEP 17 2012
AREAS AFFECTED...NERN GA...WRN CAROLINAS
CONCERNING...TORNADO WATCH 640...
VALID 180423Z - 180600Z
THE SEVERE WEATHER THREAT FOR TORNADO WATCH 640 CONTINUES.
SUMMARY...A MARGINAL/LOW-END TORNADO THREAT MAY GRADUALLY DEVELOP
E/NE OF WW 640. A DOWNSTREAM WW ISSUANCE IS NOT ANTICIPATED ATTM.
DISCUSSION...PRE-FRONTAL ARC OF N/S-ORIENTED CONVECTION HAS
STRUGGLED TO PRODUCE LIGHTNING IN NERN GA INTO THE WRN
CAROLINAS...WITH SOME LIGHTNING OBSERVED IN A CLUSTER ACROSS CNTRL
GA. LOW-LEVEL SHEAR CONTINUES TO INCREASE WITH 0-1 KM VALUES
APPROACHING 35 KT PER AREA VWP DATA. STILL...AMIDST A MEAGERLY
UNSTABLE AIR MASS CHARACTERIZED BY MLCAPE LARGELY AOB 500 J/KG PER
MODIFIED 00Z GSO RAOB AND ONLY MODEST SURFACE PRESSURE FALLS...THIS
ACTIVITY MAY STRUGGLE TO INTENSIFY. BUT A CONDITIONAL TORNADO RISK
DOES EXIST GIVEN THE STRENGTH OF THE LOW-LEVEL SHEAR...AND A
DOWNSTREAM WW ISSUANCE COULD BECOME NECESSARY IF LIGHTNING/ROTATION
TRENDS INCREASE.
..GRAMS.. 09/18/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...RAH...RNK...CHS...CAE...GSP...FFC...
LAT...LON 35528278 36408133 36398081 36198044 35858029 34768081
33408142 32658176 32188211 32118231 32168274 32458299
32878309 34038309 34938312 35528278SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 17, 8:14 PM EDT | Mesoscale Discussion | SPC | Baldwin, Banks, Barrow, Bartow, Bibb, Bleckley and 85 more | 2 hr |
| Sep 17, 10:21 PM EDT | Mesoscale Discussion | SPC | Baldwin, Banks, Barrow, Clarke, Elbert, Franklin and 21 more | 84 min |
| Sep 18, 3:44 AM EDT | Mesoscale Discussion | SPC | Baker, Calhoun, Clay, Decatur, Dougherty, Early and 7 more | 2 hr |
| Sep 18, 9:39 AM EDT | Mesoscale Discussion | SPC | Appling, Atkinson, Bacon, Ben Hill, Berrien, Brantley and 39 more | 66 min |
| Sep 18, 11:35 AM EDT | Mesoscale Discussion | SPC | Effingham, Screven | 85 min |
| Sep 18, 8:49 AM EDT | Mesoscale Discussion | SPC | Alamance, Anson, Caswell, Chatham, Cumberland, Davidson and 31 more | 116 min |
| Sep 18, 9:45 AM EDT | Tornado Watch | SPC | Alamance, Anson, Chatham, Cumberland, Davidson, Durham and 25 more | 8 hr |
| Sep 18, 10:54 AM EDT | Tornado Watch | SPC | Bertie, Camden, Caswell, Chowan, Currituck, Gates and 4 more | 9 hr |
| Sep 18, 11:19 AM EDT | Mesoscale Discussion | SPC | Alamance, Caswell, Chatham, Cumberland, Durham, Edgecombe and 27 more | 86 min |
| Sep 18, 1:00 PM EDT | Tornado Watch | SPC | Beaufort, Carteret, Craven, Dare, Duplin, Greene and 9 more | 5 hr |
| Sep 18, 1:21 PM EDT | Mesoscale Discussion | SPC | Alamance, Anson, Chatham, Cumberland, Davidson, Durham and 25 more | 84 min |
| Sep 18, 1:27 PM EDT | Mesoscale Discussion | SPC | Camden, Chowan, Currituck, Gates, Hertford, Northampton and 2 more | 63 min |
| Sep 18, 3:52 PM EDT | Mesoscale Discussion | SPC | Bertie, Camden, Chowan, Gates, Hertford, Northampton and 2 more | 113 min |
| Sep 18, 4:11 PM EDT | Mesoscale Discussion | SPC | Alamance, Anson, Beaufort, Carteret, Chatham, Craven and 40 more | 94 min |
| Sep 18, 6:15 PM EDT | Mesoscale Discussion | SPC | Camden, Carteret, Chowan, Currituck, Dare, Gates and 5 more | 30 min |
Nearby
Mesoscale Discussions in Georgia, 2012Mesoscale Discussions in North Carolina, 2012Mesoscale Discussions in South 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.