Alert archive / Alabama / Mesoscale Discussions in 2011

Mesoscale Discussion 2129

September 5, 20114 states

The Storm Prediction Center issued this mesoscale discussion at Sep 5, 2011, 4:26 AM CDT for 4 states. It was in force for 94 min.

The area

The outline as issued.

The facts

Issued
Sep 5, 2011, 4:26 AM CDT (09:26 UTC)
Expired
Sep 5, 2011, 6:00 AM CDT
In force
94 min
Issued by
the Storm Prediction Center
All 74 counties

Autauga County, AL, Baldwin County, AL, Barbour County, AL, Bibb County, AL, Bullock County, AL, Butler County, AL, Chambers County, AL, Chilton County, AL, Choctaw County, AL, Clarke County, AL, Clay County, AL, Coffee County, AL, Conecuh County, AL, Coosa County, AL, Covington County, AL, Crenshaw County, AL, Dale County, AL, Dallas County, AL, Elmore County, AL, Escambia County, AL, Fayette County, AL, Geneva County, AL, Greene County, AL, Hale County, AL, Henry County, AL, Houston County, AL, Jefferson County, AL, Lee County, AL, Lowndes County, AL, Macon County, AL, Marengo County, AL, Mobile County, AL, Monroe County, AL, Montgomery County, AL, Perry County, AL, Pickens County, AL, Pike County, AL, Russell County, AL, Shelby County, AL, St. Clair County, AL, Sumter County, AL, Talladega County, AL, Tallapoosa County, AL, Tuscaloosa County, AL, Walker County, AL, Washington County, AL, Wilcox County, AL, Bay County, FL, Calhoun County, FL, Escambia County, FL, Holmes County, FL, Jackson County, FL, Okaloosa County, FL, Santa Rosa County, FL, Walton County, FL, Washington County, FL, Clay County, GA, Early County, GA, Quitman County, GA, Seminole County, GA, Clarke County, MS, George County, MS, Greene County, MS, Jackson County, MS, Jasper County, MS, Jones County, MS, Kemper County, MS, Lauderdale County, MS, Lowndes County, MS, Neshoba County, MS, Newton County, MS, Noxubee County, MS, Perry County, MS, Wayne County, MS

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 00:00Z, 9.4 hours before the alert went out and 139 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.

Skew-T log-pSkew-T log-p diagram, Birmingham, AL at 00:00Z on 2011-09-05Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 881 joules per kilogram.LCLEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Birmingham, AL at 00:00Z on 2011-09-05The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 128 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
881 J/kg
Mixed-layer CIN
0 J/kg
Mixed-layer LCL
550 m above ground
0-6 km bulk shear
22 kt
0-1 km storm-relative helicity
128 m²/s²
0-3 km storm-relative helicity
187 m²/s²
Significant tornado parameter
0.0
Supercell composite
2.1

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

300 
ACUS11 KWNS 050926
SWOMCD
SPC MCD 050926 
FLZ000-GAZ000-ALZ000-MSZ000-051100-

MESOSCALE DISCUSSION 2129
NWS STORM PREDICTION CENTER NORMAN OK
0426 AM CDT MON SEP 05 2011

AREAS AFFECTED...EXTREME SERN LA...SERN AND ECNTRL MS...SRN AND
CNTRL AL...WRN GA AND THE FL PANHANDLE

CONCERNING...TORNADO WATCH 837...

VALID 050926Z - 051100Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 837 CONTINUES.

TORNADO WATCH 837 WILL NEED TO BE REPLACED BY ANOTHER TORNADO WATCH
BEFORE 11Z THAT WILL EXTEND FARTHER NORTH AND EAST THROUGH CNTRL AND
ERN AL AND POSSIBLY INTO EXTREME SWRN GA...REMAINING VALID THROUGH
AFTERNOON. IT APPEARS LOW LEVEL SHEAR/INSTABILITY PARAMETER SPACE
MAY BECOME MORE FAVORABLE FOR TORNADOES THAN PREVIOUS DAYS ACROSS A
PORTION OF CNTRL AND SRN AL INTO WRN GA. AREA IS BEING CONSIDERED
FOR A POSSIBLE UPGRADE TO MODERATE RISK.

TROPICAL DEPRESSION LEE OVER SERN LA IS BECOMING INFLUENCED BY A
HIGH AMPLITUDE UPPER TROUGH AMPLIFYING SEWD THROUGH THE GREAT LAKES
AND OH VALLEYS. AS A RESULT...LEE IS FORECAST TO EJECT IN A
GENERALLY NEWD DIRECTION WHILE GRADUALLY TRANSITIONING TO EXTRA
TROPICAL. SEE LATEST DISCUSSION FROM NHC FOR FURTHER INFORMATION.
SURFACE ANALYSIS SHOWS A COLD FRONT FROM WRN TN SWWD THROUGH NRN MS
INTO SERN TX. PRE-FRONTAL BOUNDARY EXTENDS FROM THE CENTER OF LEE
NEWD THROUGH E-CNTRL MS INTO N-CNTRL AL. FARTHER SOUTH A COASTAL
FRONT EXTENDS FROM THE CENTER OF LEE EWD INTO THE FL PANHANDLE. THE
COASTAL FRONT SHOULD LIFT SLOWLY NWD TODAY AS LEE EJECTS
NEWD...ALLOWING MID-UPPER 70S DEWPOINTS TO ADVECT FARTHER INTO THE
WARM SECTOR. MID-UPPER DRY AIR CONTINUES TO BE ENTRAINED INTO THE
CIRCULATION. AS HEATING OF THE MOIST BOUNDARY LAYER
COMMENCES...POTENTIAL WILL EXIST FOR 500-1000 J/KG MUCAPE IN
VICINITY OF THE COASTAL BOUNDARY DURING THE AFTERNOON WHICH SHOULD
BECOME CO-LOCATED WITH 50 KT LLJ AXIS EAST OF THE CYCLONE CENTER.
THIS SUGGESTS GREATEST TORNADO THREAT MAY EVOLVE ACROSS A PORTION OF
SRN AND CNTRL AL THROUGH SWRN AND W-CNTRL GA BY LATE MORNING INTO
THE AFTERNOON.

..DIAL.. 09/05/2011

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...FFC...TAE...BMX...HUN...MOB...JAN...LIX...

LAT...LON   30448466 29828631 30388861 32188951 33338886 33908741
            33908632 32998518 30448466

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 4, 9:42 PM CDTTornado WatchSPCAutauga, Baldwin, Butler, Choctaw, Clarke, Conecuh and 16 more9 hr
Sep 4, 11:35 PM CDTMesoscale DiscussionSPCBaldwin, Choctaw, Clarke, Conecuh, Covington, Escambia and 6 more115 min
Sep 5, 5:35 AM CDTTornado WatchSPCAutauga, Baldwin, Barbour, Bibb, Blount, Bullock and 50 more10 hr
Sep 5, 7:24 AM CDTMesoscale DiscussionSPCAutauga, Barbour, Bibb, Bullock, Butler, Calhoun and 20 more66 min
Sep 5, 11:01 AM CDTMesoscale DiscussionSPCAutauga, Baldwin, Barbour, Bibb, Blount, Bullock and 41 more29 min
Sep 5, 3:04 PM CDTSevere Thunderstorm WatchSPCCoffee, Dale, Geneva, Henry, Houston6 hr
Sep 5, 3:15 PM CDTMesoscale DiscussionSPCBarbour, Bullock, Chambers, Coffee, Dale, Elmore and 9 more30 min
Sep 5, 3:49 PM CDTTornado WatchSPCAutauga, Barbour, Bullock, Calhoun, Chambers, Chilton and 16 more4 hr
Sep 5, 6:37 PM CDTMesoscale DiscussionSPCBarbour, Bullock, Calhoun, Chambers, Clay, Cleburne and 9 more113 min
Sep 5, 5:24 PM CDTMesoscale DiscussionSPCAlachua, Baker, Columbia, Gilchrist, Hamilton, Levy and 1 more66 min
Sep 5, 11:10 AM CDTTornado WatchSPCBartow, Bibb, Butts, Carroll, Chattahoochee, Chattooga and 46 more4 hr
Sep 5, 12:23 PM CDTMesoscale DiscussionSPCBaldwin, Burke, Columbia, Elbert, Emanuel, Glascock and 17 more67 min
Sep 5, 2:05 PM CDTMesoscale DiscussionSPCBaldwin, Banks, Barrow, Bartow, Bibb, Bleckley and 75 more55 min
Sep 5, 2:42 PM CDTTornado WatchSPCBaldwin, Banks, Barrow, Bartow, Bibb, Bleckley and 81 more7 hr
Sep 5, 4:48 PM CDTMesoscale DiscussionSPCAppling, Bacon, Brantley, Bryan, Bulloch, Camden and 19 more87 min
Sep 5, 5:12 PM CDTSevere Thunderstorm WatchSPCBurke, Richmond4 hr

Nearby

Mesoscale Discussions in Alabama, 2011Mesoscale Discussions in Mississippi, 2011Mesoscale Discussions in Florida, 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.