Alert archive / Alabama / Mesoscale Discussions in 2017

Mesoscale Discussion 571

April 27, 20177 counties in Alabama; 7 counties in Georgia

The Storm Prediction Center issued this mesoscale discussion at Apr 27, 2017, 9:42 AM CDT for 7 counties in Alabama; 7 counties in Georgia. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Apr 27, 2017, 9:42 AM CDT (14:42 UTC)
Expired
Apr 27, 2017, 11:45 AM CDT
In force
2 hr
Issued by
the Storm Prediction Center
Chance of a watch
20%

Counties Barbour County, AL, Bullock County, AL, Coffee County, AL, Covington County, AL, Dale County, AL, Pike County, AL, Russell County, AL, Chattahoochee County, GA, Harris County, GA, Marion County, GA, Muscogee County, GA, Quitman County, GA, Stewart County, GA, Talbot County, GA

The radar

The Ft Rucker radar (KEOX), 45 km from the middle of the area, began a volume at 14:42 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

Peachtre/Fal Fld, GA (KFFC), launched 12:00Z, 2.7 hours before the alert went out and 194 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, Peachtre/Fal Fld, GA at 12:00Z on 2017-04-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 45 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, Peachtre/Fal Fld, GA at 12:00Z on 2017-04-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 351 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
45 J/kg
Mixed-layer CIN
-363 J/kg
Mixed-layer LCL
703 m above ground
0-6 km bulk shear
63 kt
0-1 km storm-relative helicity
351 m²/s²
0-3 km storm-relative helicity
395 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.4

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 26, 11:02 PM CDTSevere Thunderstorm WatchSPCAutauga, Bibb, Chilton, Coosa, Dallas, Elmore and 16 more6 hr
Apr 27, 1:36 AM CDTMesoscale DiscussionSPCAutauga, Bibb, Chilton, Choctaw, Clarke, Dallas and 11 more114 min
Apr 27, 12:30 PM CDTMesoscale DiscussionSPCBarbour, Russell90 min
Apr 27, 3:23 PM CDTMesoscale DiscussionSPCBarbour, Henry, Lee, Russell97 min
Apr 27, 6:26 PM CDTMesoscale DiscussionSPCBarbour, Bullock, Crenshaw, Pike, Russell64 min
Apr 27, 12:47 PM CDTTornado WatchSPCBaldwin, Bibb, Bleckley, Burke, Butts, Chattahoochee and 44 more8 hr
Apr 27, 2:29 PM CDTMesoscale DiscussionSPCBanks, Forsyth, Franklin, Habersham, Hall, Hart and 7 more91 min

Nearby

Mesoscale Discussions in Alabama, 2017Mesoscale Discussions in Georgia, 2017Every mesoscale discussion in 2017

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.