Alert archive / Alabama / Mesoscale Discussions in 2012
Mesoscale Discussion 1875
The Storm Prediction Center issued this mesoscale discussion at Sep 3, 2012, 6:55 PM CDT for 25 counties in Alabama; 12 counties in Mississippi. It was in force for 65 min.
The area
The outline as issued.
The facts
- Issued
- Sep 3, 2012, 6:55 PM CDT (23:55 UTC)
- Expired
- Sep 3, 2012, 8:00 PM CDT
- In force
- 65 min
- Issued by
- the Storm Prediction Center
All 37 counties
Autauga County, AL, Bibb County, AL, Butler County, AL, Chilton County, AL, Choctaw County, AL, Clarke County, AL, Conecuh County, AL, Crenshaw County, AL, Dallas County, AL, Elmore County, AL, Fayette County, AL, Greene County, AL, Hale County, AL, Lamar County, AL, Lowndes County, AL, Marengo County, AL, Monroe County, AL, Montgomery County, AL, Perry County, AL, Pickens County, AL, Pike County, AL, Sumter County, AL, Tuscaloosa County, AL, Washington County, AL, Wilcox County, AL, Clarke County, MS, Clay County, MS, Jasper County, MS, Kemper County, MS, Lauderdale County, MS, Lowndes County, MS, Neshoba County, MS, Newton County, MS, Noxubee County, MS, Oktibbeha County, MS, Wayne County, MS, Winston County, MS
The radar
The Birmingham radar (KBMX), 101 km from the middle of the area, began a volume at 23:55 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
Birmingham, AL (KBMX), launched 12:00Z, 11.9 hours before the alert went out and 101 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.
950
ACUS11 KWNS 032356
SWOMCD
SPC MCD 032355
ALZ000-MSZ000-040100-
MESOSCALE DISCUSSION 1875
NWS STORM PREDICTION CENTER NORMAN OK
0655 PM CDT MON SEP 03 2012
AREAS AFFECTED...ERN MS...WRN AL
CONCERNING...TORNADO WATCH 612...
VALID 032355Z - 040100Z
THE SEVERE WEATHER THREAT FOR TORNADO WATCH 612 CONTINUES.
SUMMARY...THE THREAT FOR DAMAGING WINDS AND POSSIBLY A TORNADO OR
TWO CONTINUES ACROSS THE WATCH AREA. TRAINING CELLS OVER W-CNTRL AL
WILL ALSO PROMOTE A FLASH FLOOD THREAT.
DISCUSSION...RECENT RADAR TRENDS ACROSS THE WATCH AREA INDICATE
SEGMENTS OF BOTH FORWARD-PROPAGATION AND UPWIND-PROPAGATION. THE
FORWARD-PROPAGATING PORTION OF THE MCS CONTINUES TO PROGRESS SEWD
THROUGH MONTGOMERY AND LOWNDES COUNTIES IN AL WHILE THE
UPWIND-PROPAGATING SEGMENT OVER W-CNTRL AL HAS EXHIBITED SLOW SWLY
MOTION. AS SUCH...THE PRIMARY THREAT FOR DAMAGING WINDS IS ALONG AND
AHEAD OF THE FORWARD-PROPAGATING SEGMENT. BMX VAD WIND PROFILE STILL
SHOWS STRONG LOW-LEVEL SHEAR WITH 0-1 KM BULK SHEAR AROUND 20 KT AND
0-1 KM SRH AROUND 160 M2 PER S2. THIS ENVIRONMENT IS STILL
SUPPORTIVE OF TRANSIENT ROTATION AND THE POSSIBILITY OF A BRIEF
TORNADO...ESPECIALLY ON THE LEADING EDGE OF THE FORWARD-PROPAGATING
LINE SEGMENT.
THE UPWIND-PROPAGATING PORTION OF THE LINE WILL SUPPORT HEAVY
RAINFALL AND POTENTIAL FLASH FLOODING. A VERY MOIST ATMOSPHERIC
PROFILE /PWATS OVER 2 INCHES PER THE LATEST MESOANALYSIS/ AND CELL
MERGERS WILL LIKELY RESULT IN RAINFALL RATES OVER 2 INCHES PER HOUR.
COOLING CLOUD TOP TEMPERATURES HAVE BEEN OBSERVED ACROSS W-CNTRL AL
ON THE LATEST SATELLITE IMAGERY...CONFIRMING THE PRESENCE OF CELLS
WITH A HIGH PRECIPITATION EFFICIENCY. A DAMAGING WIND GUSTS IS ALSO
POSSIBLE IN THIS AREA AS A RESULT OF LOCALIZED UPDRAFT ENHANCEMENT
AND PRECIPITATION LOADING. ADDITIONALLY...SOME ORGANIZATION OF THIS
LINE SEGMENT IS POSSIBLE. THE LATEST MESOANALYSIS INDICATES
EFFECTIVE SHEAR VECTORS ARE NELY...WHICH COULD AID IN COLD POOL
ORGANIZATION AND SWWD PROGRESSION OF THE LINE SEGMENT INTO AN AIR
MASS CHARACTERIZED BY TEMPERATURES AROUND 90...DEWPOINTS IN THE MID
70S...AND MLCAPE AROUND 2000 TO 2500 J/KG. IF THIS OCCURS...AN
ENHANCED WIND THREAT IS LIKELY ACROSS ERN MS AND WRN AL.
..MOSIER.. 09/03/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...TAE...BMX...MOB...MEG...JAN...
LAT...LON 33698825 34048821 34058795 33928795 33928762 33868751
33708755 33678742 33598742 33588733 33278709 33048692
33088661 32928648 32758641 32758590 32468589 32428606
32278591 32248599 32078601 31988587 31868565 31608574
31638617 31558614 31538672 31488669 31398661 31338669
31218670 31218676 31278680 31278751 31228759 31308773
31298784 31158786 31168802 31158820 31148843 31428846
31448893 31828893 31818932 33108932 33108922 33188923
33198911 33568909 33578901 33738904 33778892 33838891
33808872 33678871 33678846 33698825SPC 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, 12:29 PM CDT | Mesoscale Discussion | SPC | Barbour, Bullock, Butler, Clarke, Coffee, Conecuh and 11 more | 61 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 |
Nearby
Mesoscale Discussions in Alabama, 2012Mesoscale Discussions in Mississippi, 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.