Alert archive / Missouri / Mesoscale Discussions in 2017

Mesoscale Discussion 775

May 19, 201714 counties in Illinois; 15 counties in Missouri

The Storm Prediction Center issued this mesoscale discussion at May 19, 2017, 4:07 AM CDT for 14 counties in Illinois; 15 counties in Missouri. It was in force for 113 min.

The area

The outline as issued.

The facts

Issued
May 19, 2017, 4:07 AM CDT (09:07 UTC)
Expired
May 19, 2017, 6:00 AM CDT
In force
113 min
Issued by
the Storm Prediction Center
Chance of a watch
95%
All 29 counties

Bond County, IL, Calhoun County, IL, Clinton County, IL, Fayette County, IL, Greene County, IL, Jersey County, IL, Macoupin County, IL, Madison County, IL, Marion County, IL, Monroe County, IL, Montgomery County, IL, Randolph County, IL, Saint Clair County, IL, Washington County, IL, Callaway County, MO, City of Saint Louis, MO, Crawford County, MO, Franklin County, MO, Gasconade County, MO, Jefferson County, MO, Lincoln County, MO, Montgomery County, MO, Osage County, MO, Saint Charles County, MO, Saint Francois County, MO, Saint Louis County, MO, Sainte Genevieve County, MO, Warren County, MO, Washington County, MO

The radar

The St Louis radar (KLSX), 24 km from the middle of the area, began a volume at 09:08 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

Lincoln, IL (KILX), launched 00:00Z, 9.1 hours before the alert went out and 253 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, Lincoln, IL at 00:00Z on 2017-05-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 631 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, Lincoln, IL at 00:00Z on 2017-05-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 17 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
631 J/kg
Mixed-layer CIN
-32 J/kg
Mixed-layer LCL
2069 m above ground
0-6 km bulk shear
26 kt
0-1 km storm-relative helicity
17 m²/s²
0-3 km storm-relative helicity
30 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.7

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
May 19, 4:16 AM CDTSevere Thunderstorm WatchSPCBond, Calhoun, Clinton, Fayette, Greene, Jersey and 8 more3 hr
May 19, 6:30 AM CDTMesoscale DiscussionSPCBond, Clay, Clinton, Crawford, Cumberland, Effingham and 9 more90 min
May 19, 3:06 PM CDTTornado WatchSPCCalhoun7 hr
May 19, 6:04 PM CDTMesoscale DiscussionSPCCalhoun86 min
May 18, 7:06 PM CDTMesoscale DiscussionSPCBuchanan, Caldwell, Cass, Clay, Clinton, Jackson and 4 more84 min
May 18, 9:41 PM CDTMesoscale DiscussionSPCBarry, Barton, Bates, Benton, Cass, Cedar and 18 more94 min
May 18, 9:41 PM CDTSevere Thunderstorm WatchSPCAndrew, Bates, Buchanan, Caldwell, Cass, Clay and 9 more4 hr
May 18, 10:58 PM CDTTornado WatchSPCBarry, Christian, Douglas, Greene, Howell, Lawrence and 10 more6 hr
May 18, 11:48 PM CDTMesoscale DiscussionSPCBarry, Christian, McDonald, Newton, Stone, Taney57 min
May 19, 2:13 PM CDTMesoscale DiscussionSPCBarry, Christian, Dade, Douglas, Greene, Howell and 9 more92 min
May 19, 5:03 PM CDTMesoscale DiscussionSPCButler, Dunklin, Mississippi, New Madrid, Pemiscot, Stoddard117 min

Nearby

Mesoscale Discussions in Missouri, 2017Mesoscale Discussions in Illinois, 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.