Alert archive / Georgia / Mesoscale Discussions in 2012
Mesoscale Discussion 1863
The Storm Prediction Center issued this mesoscale discussion at Sep 2, 2012, 5:13 PM CDT for 4 states. It was in force for 62 min.
The area
The outline as issued.
The facts
- Issued
- Sep 2, 2012, 5:13 PM CDT (22:13 UTC)
- Expired
- Sep 2, 2012, 6:15 PM CDT
- In force
- 62 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 80%
All 37 counties
Bibb County, AL, Calhoun County, AL, Cherokee County, AL, Clay County, AL, Cleburne County, AL, Etowah County, AL, Jefferson County, AL, Randolph County, AL, Shelby County, AL, St. Clair County, AL, Talladega County, AL, Bartow County, GA, Carroll County, GA, Catoosa County, GA, Chattooga County, GA, Cherokee County, GA, Dade County, GA, Fannin County, GA, Floyd County, GA, Gilmer County, GA, Gordon County, GA, Haralson County, GA, Murray County, GA, Paulding County, GA, Pickens County, GA, Polk County, GA, Walker County, GA, Whitfield County, GA, Cherokee County, NC, Bradley County, TN, Hamilton County, TN, Loudon County, TN, McMinn County, TN, Meigs County, TN, Monroe County, TN, Polk County, TN, Rhea County, TN
The radar
The Northeast Alabama radar (KHTX), 82 km from the middle of the area, began a volume at 22:13 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
Peachtre/Fal Fld, GA (KFFC), launched 12:00Z, 10.2 hours before the alert went out and 154 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
- 576 J/kg
- Mixed-layer CIN
- -34 J/kg
- Mixed-layer LCL
- 879 m above ground
- 0-6 km bulk shear
- 11 kt
- 0-1 km storm-relative helicity
- -2 m²/s²
- 0-3 km storm-relative helicity
- -1 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
878
ACUS11 KWNS 022214
SWOMCD
SPC MCD 022213
NCZ000-TNZ000-GAZ000-ALZ000-022315-
MESOSCALE DISCUSSION 1863
NWS STORM PREDICTION CENTER NORMAN OK
0513 PM CDT SUN SEP 02 2012
AREAS AFFECTED...NWRN GA...SERN TN...EXTREME SWRN NC
CONCERNING...SEVERE POTENTIAL...WATCH LIKELY
VALID 022213Z - 022315Z
PROBABILITY OF WATCH ISSUANCE...80 PERCENT
SUMMARY...TSTM ACTIVITY ACROSS NRN AL IS EXPECTED TO CONTINUE
PROGRESSING EWD AND WILL LIKELY REACH THE MCD AREA AROUND 23Z.
INTENSITY OF THE ACTIVITY AT THAT POINT IS STILL IN QUESTION BUT
TRENDS ARE BEING MONITORED FOR THE POSSIBILITY OF A NEW WW
DOWNSTREAM OF TOR WATCHES 608 AND 609.
DISCUSSION...THE LATEST RADAR TRENDS INDICATED THE LINE OF TSTMS
ACROSS NRN AL IS GROWING UPSCALE AND POSSIBILITY ORGANIZATION INTO A
LINEAR MCS. THE ENVIRONMENT ACROSS THE MCD AREA IS CHARACTERIZED BY
AMPLE LOW-LEVEL MOISTURE /DEWPOINTS IN THE UPPER 60S TO LOW
70S/...MODEST INSTABILITY /MLCAPE AROUND 2000 J/KG/...AND ENHANCED
LOW-LEVEL SHEAR /0-3 KM SRH AROUND 100 TO 150 M2 PER S2/. GIVEN THIS
ENVIRONMENT AND THE CURRENT RADAR TRENDS...THE PRIMARY THREAT
APPEARS TO BE STRONG WIND GUSTS WITH A MUCH LOWER POTENTIAL FOR A
BRIEF TORNADO ALONG THE LEADING EDGE.
..MOSIER/MEAD.. 09/02/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...GSP...MRX...FFC...BMX...HUN...
LAT...LON 35008553 35308526 35638501 35798479 35828443 35718411
35478395 35208400 34768409 34478422 33948466 33288522
32888645 32968727 33468731 33768702 34248587 34398556
34718558 35008553SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 2, 2:20 PM CDT | Mesoscale Discussion | SPC | Lauderdale, Limestone | 115 min |
| Sep 2, 2:49 PM CDT | Tornado Watch | SPC | Colbert, Cullman, DeKalb, Franklin, Jackson, Lauderdale and 5 more | 7 hr |
| Sep 2, 3:42 PM CDT | Tornado Watch | SPC | Fayette, Lamar, Marion, Walker, Winston | 7 hr |
| Sep 2, 5:33 PM CDT | Severe Thunderstorm Watch | SPC | Blount, Calhoun, Cherokee, Cleburne, Etowah, Jefferson and 1 more | 5 hr |
| Sep 2, 6:35 PM CDT | Mesoscale Discussion | SPC | Colbert, Franklin, Lauderdale, Lawrence, Limestone, Madison and 1 more | 85 min |
| Sep 1, 7:08 PM CDT | Severe Thunderstorm Watch | SPC | Carroll, Chester, Decatur, Fayette, Hardeman, Hardin and 4 more | 6 hr |
| Sep 1, 7:56 PM CDT | Mesoscale Discussion | SPC | Carroll, Henry, Weakley | 94 min |
| Sep 1, 9:59 PM CDT | Mesoscale Discussion | SPC | Chester, Decatur, Hardeman, Henderson, McNairy | 91 min |
Nearby
Mesoscale Discussions in Georgia, 2012Mesoscale Discussions in Alabama, 2012Mesoscale 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.