Alert archive / Alabama / Mesoscale Discussions in 2007

Mesoscale Discussion 1550

July 20, 200717 counties in Alabama; 15 counties in Georgia

The Storm Prediction Center issued this mesoscale discussion at Jul 20, 2007, 10:02 AM CDT for 17 counties in Alabama; 15 counties in Georgia. It was in force for 88 min.

The area

The outline as issued.

The facts

Issued: Jul 20, 2007, 10:02 AM CDT (15:02 UTC)
Expired: Jul 20, 2007, 11:30 AM CDT
In force: 88 min
Issued by: the Storm Prediction Center

All 32 counties

Blount County, AL, Calhoun County, AL, Cherokee County, AL, Clay County, AL, Cleburne County, AL, Cullman County, AL, Etowah County, AL, Fayette County, AL, Jefferson County, AL, Lamar County, AL, Marion County, AL, Marshall County, AL, Randolph County, AL, St. Clair County, AL, Talladega County, AL, Walker County, AL, Winston County, AL, Bartow County, GA, Carroll County, GA, Cherokee County, GA, Clayton County, GA, Cobb County, GA, Coweta County, GA, DeKalb County, GA, Douglas County, GA, Fayette County, GA, Floyd County, GA, Fulton County, GA, Haralson County, GA, Heard County, GA, Paulding County, GA, Polk County, GA

The radar

The Birmingham radar (KBMX), 83 km from the middle of the area, began a volume at 15:04 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.

Severe Thunderstorm Watch 546Jul 20, 10:20 AM CDT

The nearest sounding before it

Birmingham, AL (KBMX), launched 12:00Z, 3.0 hours before the alert went out and 83 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: 1511 J/kg
Mixed-layer CIN: -34 J/kg
Mixed-layer LCL: 996 m above ground
0-6 km bulk shear: 18 kt
0-1 km storm-relative helicity: 63 m²/s²
0-3 km storm-relative helicity: 62 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 20, 10:21 AM CDT	Severe Thunderstorm Watch	SPC	Autauga, Barbour, Bibb, Blount, Bullock, Calhoun and 33 more	8 hr
Jul 20, 2:55 PM CDT	Mesoscale Discussion	SPC	Autauga, Barbour, Bibb, Bullock, Chambers, Chilton and 24 more	2 hr
Jul 20, 6:08 PM CDT	Severe Thunderstorm Watch	SPC	Baldwin, Butler, Choctaw, Clarke, Conecuh, Covington and 6 more	5 hr
Jul 20, 12:11 PM CDT	Mesoscale Discussion	SPC	Baldwin, Ben Hill, Bibb, Bleckley, Butts, Crawford and 34 more	94 min
Jul 20, 12:47 PM CDT	Severe Thunderstorm Watch	SPC	Appling, Atkinson, Bacon, Baker, Baldwin, Ben Hill and 46 more	6 hr
Jul 20, 12:52 PM CDT	Mesoscale Discussion	SPC	Burke, Columbia, Glascock, Jefferson, Jenkins, Lincoln and 5 more	83 min
Jul 20, 2:02 PM CDT	Severe Thunderstorm Watch	SPC	Brantley, Bryan, Bulloch, Burke, Candler, Chatham and 15 more	7 hr
Jul 20, 6:34 PM CDT	Mesoscale Discussion	SPC	Brantley, Camden, Charlton, Chatham, Glynn, Liberty and 4 more	56 min

Nearby

Mesoscale Discussions in Alabama, 2007 Mesoscale Discussions in Georgia, 2007 Every mesoscale discussion in 2007

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.