Alert archive / Alabama / Mesoscale Discussions in 2012

Mesoscale Discussion 56

January 23, 20124 states

The Storm Prediction Center issued this mesoscale discussion at Jan 23, 2012, 4:02 AM CST for 4 states. It was in force for 118 min.

The area

The outline as issued.

The facts

Issued
Jan 23, 2012, 4:02 AM CST (10:02 UTC)
Expired
Jan 23, 2012, 6:00 AM CST
In force
118 min
Issued by
the Storm Prediction Center
All 72 counties

Autauga County, AL, Bibb County, AL, Blount County, AL, Butler County, AL, Calhoun County, AL, Chambers County, AL, Cherokee County, AL, Chilton County, AL, Choctaw County, AL, Clarke County, AL, Clay County, AL, Cleburne County, AL, Coosa County, AL, Cullman County, AL, Dallas County, AL, DeKalb County, AL, Elmore County, AL, Etowah County, AL, Greene County, AL, Hale County, AL, Jackson County, AL, Jefferson County, AL, Lee County, AL, Lowndes County, AL, Macon County, AL, Marengo County, AL, Marshall County, AL, Monroe County, AL, Montgomery County, AL, Perry County, AL, Randolph County, AL, Shelby County, AL, St. Clair County, AL, Sumter County, AL, Talladega County, AL, Tallapoosa County, AL, Washington County, AL, Wilcox County, AL, Catoosa County, GA, Chattooga County, GA, Dade County, GA, Floyd County, GA, Gordon County, GA, Haralson County, GA, Polk County, GA, Walker County, GA, Whitfield County, GA, Ascension Parish, LA, East Baton Rouge Parish, LA, Iberville Parish, LA, Livingston Parish, LA, Saint Helena Parish, LA, Saint John the Baptist Parish, LA, Saint Tammany Parish, LA, Tangipahoa Parish, LA, Washington Parish, LA, Clarke County, MS, Covington County, MS, Forrest County, MS, George County, MS, Greene County, MS, Hancock County, MS, Jasper County, MS, Jefferson Davis County, MS, Jones County, MS, Lamar County, MS, Marion County, MS, Pearl River County, MS, Perry County, MS, Stone County, MS, Walthall County, MS, Wayne County, MS

The radar

The Birmingham radar (KBMX), 98 km from the middle of the area, began a volume at 10:03 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 00:00Z, 10.0 hours before the alert went out and 98 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 2012-01-23Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 223 joules per kilogram.LCLLFCEL10008507005003002001001 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 2012-01-23The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 267 square meters per square second.19395878Sfc1 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
223 J/kg
Mixed-layer CIN
-30 J/kg
Mixed-layer LCL
453 m above ground
0-6 km bulk shear
40 kt
0-1 km storm-relative helicity
267 m²/s²
0-3 km storm-relative helicity
298 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.2

Open this sounding in Storm Lab

The text

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

747 
ACUS11 KWNS 231002
SWOMCD
SPC MCD 231002 
GAZ000-ALZ000-TNZ000-MSZ000-LAZ000-231200-

MESOSCALE DISCUSSION 0056
NWS STORM PREDICTION CENTER NORMAN OK
0402 AM CST MON JAN 23 2012

AREAS AFFECTED...PORTIONS SERN MS...AL EXCEPT NERN AND EXTREME
SRN...NWRN GA...SERN LA.

CONCERNING...TORNADO WATCH 11...7...

VALID 231002Z - 231200Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 11...7...CONTINUES.

CONTINUE WW E OF WRN-MOST SUBSTANTIAL CONVECTIVE BAND...EVIDENT AT
0945Z FROM MCB AREA NEWD OVER WRN AL.

MAIN TORNADO THREAT THROUGH REMAINDER PRE-DAWN HOURS SHOULD BE
ASSOCIATED WITH BKN BAND OF TSTMS...INCLUDING A FEW SUPERCELLS WITH
HISTORY OF TORNADOES AND/OR REPORTED DAMAGE...EXTENDING FROM BHM
METRO AREA SWWD TO CLARKE/LAUDERDALE COUNTIES MS AND CHOCTAW COUNTY
AL BORDER AREA.  THIS REGIME IS EXPECTED TO SHIFT EWD ACROSS
WRN/CENTRAL AL...AS INDIVIDUAL TSTMS MOVE NEWD TO ENEWD THROUGH
FAVORABLE WARM SECTOR.

WARM FRONT WAS ANALYZED FROM JUST N AND E OF BHM TO BETWEEN
AUO-ALX...THEN SWD NEAR DHN.  WARM FRONTAL ZONE...MOVING ENEWD 10-15
KT...WILL CONTAIN MOST PRONOUNCED COMBINATION OF AT LEAST MRGL
BOUNDARY-LAYER INSTABILITY WITH BACKED SFC WINDS AND ATTENDANT
SRH/HODOGRAPH ENHANCEMENT.  MODIFIED FCST SOUNDINGS AND VWP SUGGEST
400-800 J/KG EFFECTIVE SRH ALONG WARM FRONT...ONLY GRADUALLY
DIMINISHING WWD ACROSS ERN MS AS SFC WINDS SLOWLY VEER.  MLCAPE IS
ESTIMATED FROM AROUND 250 J/KG JUST E OF WARM FRONT TO 800 J/KG NEAR
MS/AL BORDER AND WWD ACROSS MUCH OF MS.  EFFECTIVE SHEAR RANGES FROM
60-70 KT OVER NRN AL TO 40-45 KT NEAR MOB.

W OF AFOREMENTIONED SUPERCELLULAR BAND...VEERED FLOW ALSO REDUCES
LOW-LEVEL CONVERGENCE...BUT SVR WITH MAIN WIND-DAMAGE THREAT STILL
IS POSSIBLE WITH ACTIVITY TO ITS W IN MS...EXTENDING SWWD ACROSS
SERN LA.

..EDWARDS.. 01/23/2012

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

ATTN...WFO...MRX...FFC...BMX...HUN...MOB...JAN...LIX...LCH...

LAT...LON   30149165 31518997 33108762 34808642 35168540 34648467
            33828502 33538522 32538512 31988605 31118771 29989024
            30149165

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jan 22, 9:47 PM CSTMesoscale DiscussionSPCColbert, Franklin, Lamar, Lauderdale, Marion58 min
Jan 22, 10:59 PM CSTTornado WatchSPCBlount, Colbert, Cullman, DeKalb, Fayette, Franklin and 17 more7 hr
Jan 23, 1:25 AM CSTMesoscale DiscussionSPCAutauga, Bibb, Blount, Calhoun, Cherokee, Chilton and 31 more2 hr
Jan 23, 2:44 AM CSTTornado WatchSPCAutauga, Barbour, Bibb, Blount, Bullock, Butler and 37 more9 hr
Jan 23, 6:38 AM CSTMesoscale DiscussionSPCAutauga, Baldwin, Barbour, Bullock, Butler, Calhoun and 27 more97 min
Jan 23, 11:30 AM CSTMesoscale DiscussionSPCBarbour, Bullock, Coffee, Crenshaw, Pike, Russell2 hr
Jan 23, 7:49 AM CSTTornado WatchSPCBibb, Carroll, Chattahoochee, Coweta, Crawford, Crisp and 24 more5 hr
Jan 22, 7:59 PM CSTMesoscale DiscussionSPCBienville, Bossier, Caddo, Claiborne, De Soto, Jackson and 6 more91 min
Jan 22, 8:37 PM CSTMesoscale DiscussionSPCBolivar, Coahoma, DeSoto, Panola, Quitman, Sunflower and 4 more83 min

Nearby

Mesoscale Discussions in Alabama, 2012Mesoscale Discussions in Mississippi, 2012Mesoscale Discussions in Georgia, 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.