Alert archive / Alabama / Mesoscale Discussions in 2011
Mesoscale Discussion 283
The Storm Prediction Center issued this mesoscale discussion at Mar 26, 2011, 6:03 PM CDT for 11 counties in Alabama. It was in force for 27 min.
The area
The outline as issued.
The facts
- Issued
- Mar 26, 2011, 6:03 PM CDT (23:03 UTC)
- Expired
- Mar 26, 2011, 6:30 PM CDT
- In force
- 27 min
- Issued by
- the Storm Prediction Center
Counties Blount County, AL, Cherokee County, AL, Cullman County, AL, DeKalb County, AL, Etowah County, AL, Franklin County, AL, Lawrence County, AL, Marion County, AL, Marshall County, AL, Morgan County, AL, Winston County, AL
The radar
The Northeast Alabama radar (KHTX), 93 km from the middle of the area, began a volume at 23:06 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
Birmingham, AL (KBMX), launched 12:00Z, 11.1 hours before the alert went out and 119 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
- 54 J/kg
- Mixed-layer CIN
- -256 J/kg
- Mixed-layer LCL
- 809 m above ground
- 0-6 km bulk shear
- 54 kt
- 0-1 km storm-relative helicity
- 147 m²/s²
- 0-3 km storm-relative helicity
- 185 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted, in the capitals the NWS used until 2016.
641
ACUS11 KWNS 262304
SWOMCD
SPC MCD 262303
ALZ000-MSZ000-262330-
MESOSCALE DISCUSSION 0283
NWS STORM PREDICTION CENTER NORMAN OK
0603 PM CDT SAT MAR 26 2011
AREAS AFFECTED...NERN MS AND NRN AL
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 262303Z - 262330Z
A NEW WW MAY BE NEEDED DURING THE EARLY EVENING ACROSS MAINLY NRN
AL.
LATE AFTERNOON SURFACE ANALYSES SHOWED AN AREA OF LOW PRESSURE HAD
FORMED AND WAS TRACKING EWD INTO EXTREME NWRN AL ALONG A SURFACE
BOUNDARY WHICH EXTENDED E THEN SE AS A WARM FRONT INTO NRN TO ERN
AL. MEANWHILE...A COLD FRONT TRAILING SWWD FROM THE AL LOW WAS
MOVING SLOWLY SWD THROUGH NERN-WEST CENTRAL MS. OF PARTICULAR
CONCERN FOR NEW TSTM DEVELOPMENT IS THE RECENT DESTABILIZATION OF
THE AIR MASS ACROSS NRN AL WHERE LATE DAY SURFACE HEATING/LOW LEVEL
MOISTURE ADVECTION HAS OCCURRED AS SURFACE WINDS HAVE BECOME SSWLY
WITH THE NWD MOVEMENT OF THE WARM FRONT. OBJECTIVE ANALYSES
INDICATED THE WARM SECTOR IS MODERATELY UNSTABLE WITH MLCAPE
1000-2000 J/KG.
THE COVERAGE/INTENSITY...PER REGIONAL RADAR IMAGERY...OF ELEVATED
TSTMS ONGOING FROM SRN MIDDLE TN TO FAR NRN MS SUGGESTS THE FORCING
FOR ASCENT ATTENDANT TO A SHORTWAVE TROUGH TRACKING INTO THE OH
VALLEY/ENTRANCE REGION OF 70 KT WLY MIDLEVEL JET IS SUFFICIENTLY
STRONG. THUS...AS THIS FORCING PROGRESSES EWD ACROSS THE NRN EXTENT
OF THE WARM SECTOR...CELLS ALREADY DEVELOPING ALONG THE COLD FRONT
IN NERN MS AND THE WARM FRONT OVER NORTH CENTRAL AL SHOULD BECOME
MORE ROBUST. EFFECTIVE BULK SHEAR AROUND 50 KT AND ENHANCED LOW
LEVEL SHEAR /EFFECTIVE SRH 200-300 M2 PER S2/ WILL SUPPORT
SUPERCELLS WITH AN ATTENDANT TORNADO AND LARGE HAIL POTENTIAL.
..PETERS.. 03/26/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...BMX...HUN...MEG...
LAT...LON 33968561 33818652 33958808 34148829 34648804 34748724
34648626 34578557 34048546 33968561SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 26, 10:21 AM CDT | Mesoscale Discussion | SPC | Autauga, Bibb, Chambers, Chilton, Clay, Coosa and 17 more | 54 min |
| Mar 26, 11:25 AM CDT | Mesoscale Discussion | SPC | Autauga, Bibb, Blount, Calhoun, Chambers, Chilton and 24 more | 95 min |
| Mar 26, 12:15 PM CDT | Tornado Watch | SPC | Autauga, Barbour, Bibb, Blount, Bullock, Butler and 42 more | 8 hr |
| Mar 26, 2:23 PM CDT | Mesoscale Discussion | SPC | Autauga, Barbour, Bibb, Blount, Bullock, Butler and 47 more | 97 min |
| Mar 26, 6:59 PM CDT | Mesoscale Discussion | SPC | Barbour, Bullock, Calhoun, Chambers, Clay, Cleburne and 18 more | 91 min |
Nearby
Mesoscale Discussions in Alabama, 2011Every mesoscale discussion in 2011
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.