Alert archive / Georgia / Mesoscale Discussions in 2015
Mesoscale Discussion 1981
The Storm Prediction Center issued this mesoscale discussion at Nov 18, 2015, 1:17 PM EST for 24 counties in Georgia. It was in force for 88 min.
The area
The outline as issued.
The facts
- Issued
- Nov 18, 2015, 1:17 PM EST (18:17 UTC)
- Expired
- Nov 18, 2015, 2:45 PM EST
- In force
- 88 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 60%
All 24 counties
Bartow County, GA, Butts County, GA, Carroll County, GA, Clayton County, GA, Cobb County, GA, Coweta County, GA, DeKalb County, GA, Douglas County, GA, Fayette County, GA, Fulton County, GA, Haralson County, GA, Harris County, GA, Heard County, GA, Henry County, GA, Lamar County, GA, Meriwether County, GA, Newton County, GA, Paulding County, GA, Pike County, GA, Polk County, GA, Rockdale County, GA, Spalding County, GA, Troup County, GA, Upson County, GA
The radar
The Atlanta radar (KFFC), 2 km from the middle of the area, began a volume at 18:19 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, 6.3 hours before the alert went out and 9 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 548 m above ground
- 0-6 km bulk shear
- 41 kt
- 0-1 km storm-relative helicity
- 399 m²/s²
- 0-3 km storm-relative helicity
- 497 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
762
ACUS11 KWNS 181818
SWOMCD
SPC MCD 181817
GAZ000-ALZ000-181945-
MESOSCALE DISCUSSION 1981
NWS STORM PREDICTION CENTER NORMAN OK
1217 PM CST WED NOV 18 2015
AREAS AFFECTED...NORTHWESTERN/WEST-CENTRAL GEORGIA
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 181817Z - 181945Z
PROBABILITY OF WATCH ISSUANCE...60 PERCENT
SUMMARY...CONVECTION ENTERING WESTERN PARTS OF THE DISCUSSION AREA
WILL POSE AN ISOLATED TORNADO/WIND DAMAGE THREAT THIS AFTERNOON AND
EARLY EVENING. CONVECTIVE TRENDS ARE BEING MONITORED FOR A POSSIBLE
WW ISSUANCE.
DISCUSSION...A LINE OF CONVECTION HAS MOVED STEADILY EAST ACROSS
EAST-CENTRAL/NORTHEAST ALABAMA THIS MORNING...WITH MORE CELLULAR
ACTIVITY IN A SMALL PART OF EAST-CENTRAL ALABAMA NEAR CLAY/COOSA
COUNTIES. THE ENVIRONMENT FOSTERING THIS CONVECTION IS
CHARACTERIZED BY VERY WEAK INSTABILITY /LESS THAN 500 J/KG MUCAPE/
BUT STRONG LOW AND DEEP SHEAR FAVORING STORM ORGANIZATION AND
OCCASIONAL ROTATION WITHIN INDIVIDUAL CELLS.
ADDITIONALLY...LEWP-TYPE STRUCTURES HAVE DEVELOPED WITHIN THE
AFOREMENTIONED LINE IN THE PAST HOUR OR SO...ESPECIALLY IN
DEKALB/CALHOUN COUNTIES IN ALABAMA.
WITH TIME... CONTINUED WARM/MOIST LOW-LEVEL ADVECTION AND POCKETS OF
INSOLATION AHEAD OF THE CONVECTIVE BAND BENEATH A WIDESPREAD CIRRUS
DECK WILL LEAD TO GRADUALLY INCREASING INSTABILITY ACROSS THE
DISCUSSION AREA. ADDITIONALLY...A WEAK SHORTWAVE ACROSS EAST
TEXAS/LOUISIANA WILL MOVE TOWARD THE AREA THIS AFTERNOON AND
POSSIBLY PROVIDE IMPETUS FOR A WEAK MESO-LOW/FRONTAL WAVE ACROSS
ALABAMA. AS THIS OCCURS...STRENGTHENING LOW-LEVEL WARM ADVECTION
WILL HELP ERODE THE WEDGE FRONT CURRENTLY OVER NORTH-CENTRAL GEORGIA
AND RESULT IN AN ATTENDANT INCREASE IN RISK OF ISOLATED SEVERE
WIND/TORNADO THREAT IN PARTS OF THAT AREA...INCLUDING THE ATLANTA
METRO.
THE REGION WILL BE MONITORED FOR A POSSIBLE TORNADO WATCH THIS
AFTERNOON.
..COOK/MEAD.. 11/18/2015
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...FFC...BMX...
LAT...LON 32758432 32728451 32718501 32898527 33188541 33498547
33818543 34128528 34268489 34128426 33868391 33568381
33408377 33268379 32968402 32758432SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Nov 18, 11:51 AM EST | Mesoscale Discussion | SPC | Baker, Calhoun, Chattahoochee, Clay, Decatur, Dougherty and 16 more | 114 min |
| Nov 18, 2:39 PM EST | Mesoscale Discussion | SPC | Baker, Calhoun, Clay, Decatur, Dougherty, Early and 8 more | 2 hr |
| Nov 18, 3:16 PM EST | Tornado Watch | SPC | Baker, Bibb, Calhoun, Chattahoochee, Clay, Crawford and 31 more | 6 hr |
| Nov 18, 6:35 PM EST | Mesoscale Discussion | SPC | Baker, Baldwin, Bibb, Bleckley, Brooks, Butts and 55 more | 115 min |
Nearby
Mesoscale Discussions in Georgia, 2015Every mesoscale discussion in 2015
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.