Alert archive / Alabama / Mesoscale Discussions in 2003

Mesoscale Discussion 821

May 7, 200320 counties in Alabama; 14 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at May 7, 2003, 1:42 PM CDT for 20 counties in Alabama; 14 counties in Mississippi. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: May 7, 2003, 1:42 PM CDT (18:42 UTC)
Expired: May 7, 2003, 3:45 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center

All 34 counties

Autauga County, AL, Baldwin County, AL, Bullock County, AL, Butler County, AL, Choctaw County, AL, Clarke County, AL, Coffee County, AL, Conecuh County, AL, Covington County, AL, Crenshaw County, AL, Dallas County, AL, Escambia County, AL, Lowndes County, AL, Marengo County, AL, Mobile County, AL, Monroe County, AL, Montgomery County, AL, Pike County, AL, Washington County, AL, Wilcox County, AL, Clarke County, MS, Covington County, MS, Forrest County, MS, George County, MS, Greene County, MS, Harrison County, MS, Jackson County, MS, Jasper County, MS, Jones County, MS, Lamar County, MS, Pearl River County, MS, Perry County, MS, Stone County, MS, Wayne County, MS

The watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Tornado Watch 288May 7, 3:00 PM CDT

The nearest sounding before it

Eglin AFB/Valpar, FL (KVPS), launched 12:00Z, 6.7 hours before the alert went out and 191 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 1132 J/kg
Mixed-layer CIN: -55 J/kg
Mixed-layer LCL: 733 m above ground
0-6 km bulk shear: 34 kt
0-1 km storm-relative helicity: 61 m²/s²
0-3 km storm-relative helicity: 74 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 2.1

Open this sounding in Storm Lab

The text

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

958 
ACUS11 KWNS 071842
SWOMCD
SPC MCD 071842 
ALZ000-FLZ000-MSZ000-LAZ000-072045-

MESOSCALE DISCUSSION 0821
NWS STORM PREDICTION CENTER NORMAN OK
0142 PM CDT WED MAY 07 2003

AREAS AFFECTED...SRN MS/SRN AL

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 071842Z - 072045Z

CONVECTION MAY CONTINUE TO DEVELOP ACROSS SRN MS AND SRN AL AND WILL
HAVE THE POTENTIAL FOR LARGE HAIL AND DAMAGING WINDS. WW MAY BE
REQUIRED IN THE NEXT HOUR.

VIS SAT IMAGERY SHOWED A DEVELOPING CU FIELD ACROSS SRN MS/SRN AL.
STRONG SFC HEATING WITH TEMPS IN THE MID TO UPPER 80S F HAVE
PRODUCED A VERY UNSTABLE AIR MASS IN THIS REGION. A CENTER OF
INSTABILITY EXISTED N OF MOBILE AL AND STORM INITIATION WAS
BEGINNING TO THE NW OF THIS POINT. 0-6 KM SHEAR IN THIS REGION WAS
AROUND 45 KT. THE LOW-LEVEL JET WAS LOCATED IN ERN MS AND HAS
CREATED 0-3 KM HELICITY VALUES AROUND 200 M2/S2 FAVORING STORM
ROTATION. DECENT DEEP LAYER SHEAR AND STRONG INSTABILITY WILL MAKE
SUPERCELL DEVELOPMENT POSSIBLE. SUPERCELLS WILL HAVE THE POTENTIAL
FOR LARGE HAIL AND DAMAGING WINDS. ISOLATED TORNADOES WILL ALSO BE
POSSIBLE ESPECIALLY NEARER TO THE LOW-LEVEL JET AXIS. WW MAY BE
REQUIRED SOON IF ACTIVITY CONTINUES TO INCREASE. 


..BROYLES.. 05/07/2003

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

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

32088901 32328828 32548734 32598624 32278550 31508562
30768715 30338902 30748985 31758976

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 6, 11:32 PM CDT	Mesoscale Discussion	SPC	Jackson, Limestone, Madison	88 min
May 6, 11:50 PM CDT	Tornado Watch	SPC	Colbert, Lauderdale, Lawrence, Limestone, Madison, Morgan	6 hr
May 7, 1:41 AM CDT	Mesoscale Discussion	SPC	Colbert, Franklin, Lauderdale, Lawrence, Limestone, Madison and 1 more	3 hr
May 7, 4:55 AM CDT	Tornado Watch	SPC	Lauderdale	6 hr
May 7, 7:06 AM CDT	Mesoscale Discussion	SPC	Colbert, Cullman, Fayette, Franklin, Jackson, Lamar and 8 more	114 min
May 7, 7:35 AM CDT	Tornado Watch	SPC	Blount, Colbert, Cullman, Fayette, Franklin, Greene and 16 more	5 hr
May 7, 10:24 AM CDT	Mesoscale Discussion	SPC	Bibb, Blount, Calhoun, Chambers, Cherokee, Chilton and 20 more	2 hr
May 7, 10:35 AM CDT	Tornado Watch	SPC	Bibb, Blount, Calhoun, Chambers, Cherokee, Chilton and 23 more	5 hr
May 7, 10:50 AM CDT	Tornado Watch	SPC	Sumter	5 hr
May 7, 2:30 PM CDT	Tornado Watch	SPC	Russell	6 hr
May 7, 3:00 PM CDT	Tornado Watch	SPC	Autauga, Barbour, Bibb, Bullock, Butler, Calhoun and 30 more	6 hr
May 7, 6:29 PM CDT	Mesoscale Discussion	SPC	Autauga, Barbour, Bibb, Bullock, Butler, Calhoun and 32 more	91 min
May 6, 7:15 PM CDT	Severe Thunderstorm Watch	SPC	Adams, Attala, Carroll, Choctaw, Claiborne, Clarke and 36 more	5 hr
May 6, 9:53 PM CDT	Mesoscale Discussion	SPC	Attala, Carroll, Chickasaw, Choctaw, Claiborne, Clarke and 32 more	97 min
May 7, 2:27 AM CDT	Mesoscale Discussion	SPC	Attala, Bolivar, Calhoun, Carroll, Chickasaw, Choctaw and 36 more	3 hr
May 7, 9:47 AM CDT	Mesoscale Discussion	SPC	Adams, Attala, Calhoun, Carroll, Chickasaw, Choctaw and 25 more	118 min
May 7, 1:54 PM CDT	Mesoscale Discussion	SPC	Attala, Carroll, Choctaw, Claiborne, Clay, Hinds and 23 more	2 hr

Nearby

Mesoscale Discussions in Alabama, 2003 Mesoscale Discussions in Mississippi, 2003 Every mesoscale discussion in 2003

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.