Alert archive / Alabama / Mesoscale Discussions in 2012

Mesoscale Discussion 1826

August 28, 20124 states

The Storm Prediction Center issued this mesoscale discussion at Aug 28, 2012, 7:01 AM CDT for 4 states. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Aug 28, 2012, 7:01 AM CDT (12:01 UTC)
Expired
Aug 28, 2012, 9:30 AM CDT
In force
2 hr
Issued by
the Storm Prediction Center
Chance of a watch
40%
All 24 counties

Baldwin County, AL, Clarke County, AL, Coffee County, AL, Conecuh County, AL, Covington County, AL, Escambia County, AL, Geneva County, AL, Mobile County, AL, Monroe County, AL, Washington County, AL, Bay County, FL, Calhoun County, FL, Escambia County, FL, Gulf County, FL, Holmes County, FL, Okaloosa County, FL, Santa Rosa County, FL, Walton County, FL, Washington County, FL, Saint Bernard Parish, LA, George County, MS, Greene County, MS, Harrison County, MS, Jackson County, MS

The radar

The Eglin Afb radar (KEVX), 109 km from the middle of the area, began a volume at 12:04 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.

The nearest sounding before it

Tallahassee Rgnl, FL (KTLH), launched 12:00Z, 0.0 hours before the alert went out and 255 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, Tallahassee Rgnl, FL at 12:00Z on 2012-08-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1339 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, Tallahassee Rgnl, FL at 12:00Z on 2012-08-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 166 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
1339 J/kg
Mixed-layer CIN
-2 J/kg
Mixed-layer LCL
482 m above ground
0-6 km bulk shear
17 kt
0-1 km storm-relative helicity
166 m²/s²
0-3 km storm-relative helicity
161 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.

IssuedProductOfficeCountiesLasted
Aug 28, 9:46 AM CDTTornado WatchSPCBaldwin, Choctaw, Clarke, Conecuh, Escambia, Mobile and 2 more9 hr
Aug 28, 12:37 PM CDTMesoscale DiscussionSPCBaldwin, Escambia, Mobile, Washington83 min
Aug 28, 3:46 PM CDTMesoscale DiscussionSPCBaldwin, Clarke, Escambia, Mobile, Monroe, Washington89 min
Aug 28, 5:48 PM CDTMesoscale DiscussionSPCBaldwin, Conecuh, Covington, Escambia, Mobile, Monroe and 1 more87 min
Aug 28, 6:47 PM CDTTornado WatchSPCBaldwin, Choctaw, Clarke, Conecuh, Escambia, Mobile and 2 more21 hr
Aug 28, 12:56 PM CDTTornado WatchSPCCovington, Forrest, Jefferson Davis, Jones, Lamar, Lawrence and 2 more6 hr

Nearby

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