Alert archive / Alabama / Mesoscale Discussions in 2012
Mesoscale Discussion 1869
The Storm Prediction Center issued this mesoscale discussion at Sep 3, 2012, 12:29 PM CDT for 17 counties in Alabama; Holmes County, Jackson County, Santa Rosa County, Florida; 14 counties in Georgia. It was in force for 61 min.
The area
The outline as issued.
The facts
- Issued
- Sep 3, 2012, 12:29 PM CDT (17:29 UTC)
- Expired
- Sep 3, 2012, 1:30 PM CDT
- In force
- 61 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 40%
All 34 counties
Barbour County, AL, Bullock County, AL, Butler County, AL, Clarke County, AL, Coffee County, AL, Conecuh County, AL, Covington County, AL, Crenshaw County, AL, Dale County, AL, Escambia County, AL, Geneva County, AL, Henry County, AL, Houston County, AL, Lowndes County, AL, Monroe County, AL, Pike County, AL, Wilcox County, AL, Holmes County, FL, Jackson County, FL, Santa Rosa County, FL, Baker County, GA, Calhoun County, GA, Clay County, GA, Decatur County, GA, Dougherty County, GA, Early County, GA, Miller County, GA, Mitchell County, GA, Quitman County, GA, Randolph County, GA, Seminole County, GA, Stewart County, GA, Terrell County, GA, Webster County, GA
The watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Birmingham, AL (KBMX), launched 12:00Z, 5.5 hours before the alert went out and 197 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
- 215 J/kg
- Mixed-layer CIN
- -149 J/kg
- Mixed-layer LCL
- 1125 m above ground
- 0-6 km bulk shear
- 25 kt
- 0-1 km storm-relative helicity
- 60 m²/s²
- 0-3 km storm-relative helicity
- 93 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted, in the capitals the NWS used until 2016.
909
ACUS11 KWNS 031730
SWOMCD
SPC MCD 031729
GAZ000-FLZ000-ALZ000-031830-
MESOSCALE DISCUSSION 1869
NWS STORM PREDICTION CENTER NORMAN OK
1229 PM CDT MON SEP 03 2012
AREAS AFFECTED...SRN AL...SWRN GA...FL PANHANDLE
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 031729Z - 031830Z
PROBABILITY OF WATCH ISSUANCE...40 PERCENT
SUMMARY...THUNDERSTORMS ARE EXPECTED TO INCREASE IN COVERAGE AND
SEVERITY THIS AFTERNOON...POSSIBLY PRODUCING DMGG WINDS AND HEAVY
RAINFALL AS THEY PROGRESS ESEWD WITH TIME.
DISCUSSION...USING MODIFIED AREA 12Z SOUNDINGS WITH 17Z SURFACE
OBSERVATIONS...CONVECTIVE INHIBITION SHOULD BE ERODED SHORTLY...WITH
A SUBSEQUENT INCREASE IN SURFACE-BASED STORMS EXPECTED. ONGOING
STORMS S OF MGM AND LSF AMIDST A RELATIVE MOIST AXIS CHARACTERIZED
BY MID-70S DEW POINTS SHOULD SERVE AS A LIKELY FOCUS FOR NEW
ACTIVITY AS OUTFLOW BOUNDARIES ARE GENERATED IN A DEEPLY SATURATED
AIR MASS. AS MORE ROBUST UPDRAFTS DEVELOP...VEERING WINDS WITH
HEIGHT WILL SUPPORT BRIEF/TRANSIENT CIRCULATIONS...WITH AN ATTENDANT
THREAT OF DMGG WINDS AND/OR A BRIEF TORNADO.
..HURLBUT/CORFIDI.. 09/03/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...FFC...TAE...BMX...MOB...
LAT...LON 31998784 32188687 32228541 32068426 31178403 30678475
30618630 30678774 30958807 31998784SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 2, 7:13 PM CDT | Mesoscale Discussion | SPC | Colbert, Fayette, Franklin, Lamar, Lauderdale, Lawrence and 3 more | 62 min |
| Sep 2, 8:43 PM CDT | Mesoscale Discussion | SPC | Calhoun, Cherokee, Cleburne, DeKalb, Etowah, St. Clair | 62 min |
| Sep 2, 9:48 PM CDT | Mesoscale Discussion | SPC | Fayette, Lamar, Marion, Walker, Winston | 57 min |
| Sep 3, 3:25 PM CDT | Mesoscale Discussion | SPC | Autauga, Barbour, Bibb, Bullock, Butler, Chilton and 16 more | 65 min |
| Sep 3, 3:46 PM CDT | Tornado Watch | SPC | Autauga, Bibb, Butler, Chilton, Choctaw, Clarke and 19 more | 7 hr |
| Sep 3, 6:55 PM CDT | Mesoscale Discussion | SPC | Autauga, Bibb, Butler, Chilton, Choctaw, Clarke and 19 more | 65 min |
Nearby
Mesoscale Discussions in Alabama, 2012Mesoscale Discussions in Georgia, 2012Mesoscale Discussions in Florida, 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.