Alert archive / Alabama / Mesoscale Discussions in 2012

Mesoscale Discussion 2149

December 10, 20124 states

The Storm Prediction Center issued this mesoscale discussion at Dec 10, 2012, 10:24 AM CST for 4 states. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Dec 10, 2012, 10:24 AM CST (16:24 UTC)
Expired
Dec 10, 2012, 12:30 PM CST
In force
2 hr
Issued by
the Storm Prediction Center
All 39 counties

Autauga County, AL, Baldwin County, AL, Bullock County, AL, Butler County, AL, Chambers County, AL, Chilton County, AL, Choctaw County, AL, Clarke County, AL, Coffee County, AL, Conecuh County, AL, Coosa County, AL, Covington County, AL, Crenshaw County, AL, Dallas County, AL, Elmore County, AL, Escambia 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, Pike County, AL, Tallapoosa County, AL, Washington County, AL, Wilcox County, AL, Escambia County, FL, Okaloosa County, FL, Santa Rosa County, FL, Orleans Parish, LA, George County, MS, Greene County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Perry County, MS, Stone County, MS

The nearest sounding before it

Birmingham, AL (KBMX), launched 12:00Z, 4.4 hours before the alert went out and 135 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 12:00Z on 2012-12-10Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 385 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 12:00Z on 2012-12-10The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 218 square meters per square second.1939587897Sfc1 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
385 J/kg
Mixed-layer CIN
-1 J/kg
Mixed-layer LCL
531 m above ground
0-6 km bulk shear
52 kt
0-1 km storm-relative helicity
218 m²/s²
0-3 km storm-relative helicity
254 m²/s²
Significant tornado parameter
0.4
Supercell composite
2.7

Open this sounding in Storm Lab

The text

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

142 
ACUS11 KWNS 101625
SWOMCD
SPC MCD 101624
ALZ000-FLZ000-MSZ000-LAZ000-101830-

MESOSCALE DISCUSSION 2149
NWS STORM PREDICTION CENTER NORMAN OK
1024 AM CST MON DEC 10 2012

AREAS AFFECTED...ERN LA/SERN MS/SRN AL/WRN FL PANHANDLE

CONCERNING...TORNADO WATCH 680...

VALID 101624Z - 101830Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 680 CONTINUES.

SUMMARY...OCCASIONAL ROTATING UPDRAFTS WITHIN THE ONGOING LINE OF
STORMS WILL CONTINUE TO POSE AN ISOLATED TORNADO RISK.

DISCUSSION...BROKEN LINE OF STORMS -- WITH OCCASIONAL/EMBEDDED
ROTATING CELLS -- CONTINUES MOVING EWD ACROSS THE CENTRAL GULF COAST
REGION...WITH A FEW ISOLATED CELLS INCREASING IN A WARM ADVECTION
ZONE INVOF MOBILE AL JUST AHEAD OF THE MAIN CONVECTIVE LINE.

DEWPOINTS IN THE MID TO UPPER 60S ACROSS THIS AREA ARE CONTRIBUTING
TO AMPLE INSTABILITY FOR OCCASIONALLY VIGOROUS STORMS...AND
DEEP-LAYER SHEAR IS PLENTY SUFFICIENT FOR UPDRAFT ORGANIZATION.
GIVEN THESE FACTORS -- AND WITH 0-1 KM SHEAR SUFFICIENT FOR
LOW-LEVEL ROTATION...THREAT FOR A COUPLE OF TORNADOES CONTINUES
ALONG WITH LOCALLY DAMAGING WIND GUSTS.

WITH SOME AFOREMENTIONED INCREASE IN CONVECTION WITHIN THE WARM
ADVECTION ZONE AHEAD OF THE MAIN LINE -- WHICH IS OCCURRING NEAR THE
ERN FRINGE OF THE ONGOING WW...WE WILL MONITOR AREAS FARTHER E INTO
S CENTRAL AND SERN AL AND THE FL PANHANDLE FOR POSSIBLE ADDITIONAL
WW.

..GOSS.. 12/10/2012

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

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

LAT...LON   33218539 32308522 29958674 29919038 32388787 32858714
            33218539

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Dec 10, 7:31 AM CSTMesoscale DiscussionSPCChoctaw, Mobile, Washington119 min
Dec 10, 8:51 AM CSTTornado WatchSPCAutauga, Barbour, Bullock, Chambers, Chilton, Choctaw and 18 more6 hr
Dec 10, 12:52 PM CSTMesoscale DiscussionSPCBaldwin, Barbour, Bullock, Butler, Chambers, Coffee and 18 more113 min
Dec 10, 3:40 PM CSTMesoscale DiscussionSPCBrevard, Citrus, DeSoto, Flagler, Hardee, Hernando and 19 more2 hr
Dec 9, 8:38 PM CSTMesoscale DiscussionSPCBeauregard, Bienville, Bossier, Caddo, Caldwell, Claiborne and 15 more67 min
Dec 9, 9:59 PM CSTMesoscale DiscussionSPCConcordia, East Carroll, Franklin, Madison, Tensas61 min
Dec 9, 11:24 PM CSTMesoscale DiscussionSPCCaldwell, Catahoula, East Carroll, Franklin, Grant, LaSalle and 6 more66 min
Dec 10, 4:07 AM CSTMesoscale DiscussionSPCAcadia, Allen, Ascension, Assumption, Avoyelles, Cameron and 23 more113 min
Dec 10, 5:44 AM CSTTornado WatchSPCAscension, Assumption, East Baton Rouge, East Feliciana, Iberia, Iberville and 10 more5 hr

Nearby

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