Alert archive / Indiana / Tornado Watches in 2015

Tornado Watch 37

April 8, 201519 counties in Illinois; 22 counties in Indiana; 9 counties in Missouri

The Storm Prediction Center issued this tornado watch at Apr 8, 2015, 4:07 PM CDT for 19 counties in Illinois; 22 counties in Indiana; 9 counties in Missouri. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued
Apr 8, 2015, 4:07 PM CDT (21:07 UTC)
Expired
Apr 8, 2015, 8:15 PM CDT
In force
4 hr
Issued by
the Storm Prediction Center
Largest hail expected
2.5 in
Strongest gust expected
60 kt
All 50 counties

Edwards County, IL, Franklin County, IL, Gallatin County, IL, Hamilton County, IL, Hardin County, IL, Jackson County, IL, Jefferson County, IL, Johnson County, IL, Monroe County, IL, Perry County, IL, Pope County, IL, Randolph County, IL, Saline County, IL, Union County, IL, Wabash County, IL, Washington County, IL, Wayne County, IL, White County, IL, Williamson County, IL, Clark County, IN, Crawford County, IN, Daviess County, IN, Dubois County, IN, Floyd County, IN, Gibson County, IN, Harrison County, IN, Jackson County, IN, Jefferson County, IN, Jennings County, IN, Knox County, IN, Lawrence County, IN, Martin County, IN, Orange County, IN, Perry County, IN, Pike County, IN, Posey County, IN, Scott County, IN, Spencer County, IN, Vanderburgh County, IN, Warrick County, IN, Washington County, IN, Bollinger County, MO, Cape Girardeau County, MO, Iron County, MO, Jefferson County, MO, Madison County, MO, Perry County, MO, Saint Francois County, MO, Sainte Genevieve County, MO, Washington County, MO

The radar

The Evansville,IN radar (KVWX), 49 km from the middle of the area, began a volume at 21:11 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.

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes
40%
One or more EF2 to EF5 tornadoes
20%
Ten or more severe wind reports
40%
One or more gusts of 65 knots or more
10%
Ten or more severe hail reports
70%
One or more hailstones of 2 inches or more
40%
Six or more combined severe hail and wind reports
95%

Warnings issued inside it

22 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

IssuedProductOfficeCountiesLasted
Apr 8, 4:13 PM CDTSevere Thunderstorm WarningINDDaviess, Lawrence, Martin31 min
Apr 8, 4:17 PM CDTSevere Thunderstorm WarningLMKOrange38 min
Apr 8, 4:19 PM CDTSevere Thunderstorm WarningLMKClark, Scott, Washington31 min
Apr 8, 4:26 PM CDTTornado WarningLSXSainte Genevieve, Saint Francois34 min
Apr 8, 4:38 PM CDTSevere Thunderstorm WarningLMKWashington32 min
Apr 8, 4:45 PM CDTTornado WarningPAHBollinger, Perry45 min
Apr 8, 4:53 PM CDTTornado WarningLSXSainte Genevieve, Saint Francois37 min
Apr 8, 4:57 PM CDTFlash Flood WarningLSXSainte Genevieve, Saint Francois, Washington4 hr
Apr 8, 4:58 PM CDTSevere Thunderstorm WarningLMKClark, Jefferson, Scott32 min
Apr 8, 5:05 PM CDTTornado WarningLSXMadison, Sainte Genevieve, Saint Francois25 min
Apr 8, 5:12 PM CDTFlash Flood WarningLMKJefferson, Scott, Washington2 hr
Apr 8, 5:15 PM CDTSevere Thunderstorm WarningLMKJefferson, Scott30 min
Apr 8, 5:25 PM CDTSevere Thunderstorm WarningLSXSainte Genevieve, Saint Francois, Washington22 min
Apr 8, 5:27 PM CDTSevere Thunderstorm WarningPAHBollinger, Perry48 min
Apr 8, 5:28 PM CDTSevere Thunderstorm WarningLMKJefferson32 min
Apr 8, 5:28 PM CDTSevere Thunderstorm WarningLSXMadison, Sainte Genevieve, Saint Francois47 min
Apr 8, 5:46 PM CDTSevere Thunderstorm WarningLMKJefferson29 min
Apr 8, 5:50 PM CDTFlash Flood WarningLSXSainte Genevieve, Saint Francois3 hr
Apr 8, 6:12 PM CDTSevere Thunderstorm WarningPAHBollinger, Cape Girardeau, Perry48 min
Apr 8, 6:14 PM CDTSevere Thunderstorm WarningLSXMadison, Sainte Genevieve, Saint Francois46 min
Apr 8, 6:56 PM CDTSevere Thunderstorm WarningPAHPerry18 min
Apr 8, 8:02 PM CDTSevere Thunderstorm WarningLSXFranklin, Jefferson31 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 9.1 hours before the alert went out and 202 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 12:00Z on 2015-04-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 195 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 12:00Z on 2015-04-08The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 66 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
195 J/kg
Mixed-layer CIN
-238 J/kg
Mixed-layer LCL
839 m above ground
0-6 km bulk shear
56 kt
0-1 km storm-relative helicity
66 m²/s²
0-3 km storm-relative helicity
142 m²/s²
Significant tornado parameter
0.0
Supercell composite
7.7

Open this sounding in Storm Lab

The text

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

739 
WWUS20 KWNS 082105
SEL7  
SPC WW 082105
ILZ000-INZ000-MOZ000-090300-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 37
NWS STORM PREDICTION CENTER NORMAN OK
405 PM CDT WED APR 8 2015

THE NWS STORM PREDICTION CENTER HAS ISSUED A

* TORNADO WATCH FOR PORTIONS OF 
  SOUTHERN ILLINOIS
  SOUTHERN INDIANA
  SOUTHEAST MISSOURI

* EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 405 PM
  UNTIL 1000 PM CDT.

* PRIMARY THREATS INCLUDE...
  A COUPLE TORNADOES POSSIBLE
  SCATTERED LARGE HAIL LIKELY WITH ISOLATED VERY LARGE HAIL EVENTS
    TO 2.5 INCHES IN DIAMETER POSSIBLE
  SCATTERED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 125 STATUTE
MILES EAST AND WEST OF A LINE FROM 65 MILES NORTH NORTHEAST OF
EVANSVILLE INDIANA TO 25 MILES SOUTHEAST OF CARBONDALE ILLINOIS. 
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU7).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 33...WW 34...WW 35...WW
36...

DISCUSSION...SUPERCELL CLUSTERS THAT HAVE FORMED IN RELATIVELY WEAK
LOW-LVL SHEAR THIS AFTN MAY POSE A THREAT FOR A COUPLE TORNADOES
THROUGH EARLY TNGT GIVEN DEGREE OF BUOYANCY AND PRESENCE OF ENHANCED
SRH INVOF W-E FRONTAL SEGMENT BISECTING MAIN AXIS OF WW.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 26030.


...CORFIDI

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 8, 7:41 AM CDTMesoscale DiscussionSPCClark, Coles, Cumberland64 min
Apr 8, 12:01 PM CDTMesoscale DiscussionSPCJackson, Monroe, Perry, Randolph, Saint Clair, Washington59 min
Apr 8, 12:50 PM CDTMesoscale DiscussionSPCBond, Calhoun, Champaign, Christian, Clark, Clay and 32 more85 min
Apr 8, 1:05 PM CDTSevere Thunderstorm WatchSPCBond, Calhoun, Champaign, Christian, Clark, Clay and 42 more5 hr
Apr 8, 2:43 PM CDTMesoscale DiscussionSPCBond, Brown, Calhoun, Cass, Champaign, Christian and 45 more92 min
Apr 8, 3:42 PM CDTMesoscale DiscussionSPCFranklin, Gallatin, Hamilton, Jackson, Jefferson, Monroe and 7 more63 min
Apr 8, 9:16 AM CDTMesoscale DiscussionSPCClark, Dearborn, Jefferson, Jennings, Ohio, Ripley and 2 more119 min
Apr 8, 9:34 AM CDTSevere Thunderstorm WatchSPCDearborn, Franklin, Jefferson, Ohio, Ripley, Switzerland5 hr
Apr 7, 7:58 PM CDTMesoscale DiscussionSPCBell, Breathitt, Clay, Floyd, Harlan, Jackson and 14 more62 min
Apr 8, 10:52 AM CDTMesoscale DiscussionSPCBath, Bourbon, Boyd, Bracken, Carter, Elliott and 17 more83 min
Apr 8, 11:33 AM CDTSevere Thunderstorm WatchSPCFloyd, Johnson, Lawrence, Magoffin, Martin, Menifee and 5 more5 hr
Apr 8, 12:51 PM CDTMesoscale DiscussionSPCBoyd, Breathitt, Carter, Elliott, Floyd, Greenup and 10 more84 min
Apr 8, 1:55 PM CDTMesoscale DiscussionSPCAdair, Allen, Anderson, Barren, Boyle, Breckinridge and 54 more2 hr
Apr 8, 2:22 PM CDTMesoscale DiscussionSPCBoyd, Breathitt, Clay, Elliott, Floyd, Johnson and 12 more83 min
Apr 8, 4:50 PM CDTMesoscale DiscussionSPCAdair, Anderson, Barren, Bath, Bourbon, Boyle and 50 more115 min
Apr 7, 8:24 PM CDTSevere Thunderstorm WatchSPCBarton, Bates, Benton, Cass, Cedar, Cooper and 13 more5 hr
Apr 7, 10:13 PM CDTMesoscale DiscussionSPCBarton, Bates, Benton, Cass, Cedar, Henry and 6 more2 hr
Apr 8, 6:17 AM CDTMesoscale DiscussionSPCBates, Benton, Boone, Callaway, Camden, Cass and 19 more88 min
Apr 8, 6:39 AM CDTSevere Thunderstorm WatchSPCAdair, Audrain, Barton, Bates, Benton, Boone and 54 more6 hr
Apr 8, 9:33 AM CDTMesoscale DiscussionSPCAdair, Audrain, Benton, Boone, Caldwell, Callaway and 45 more57 min
Apr 8, 2:21 PM CDTMesoscale DiscussionSPCBarry, Barton, Bates, Benton, Camden, Cass and 16 more114 min
Apr 8, 2:47 PM CDTSevere Thunderstorm WatchSPCBarry, Barton, Bates, Benton, Camden, Cass and 29 more4 hr
Apr 8, 5:45 PM CDTMesoscale DiscussionSPCAudrain, Bates, Benton, Boone, Caldwell, Callaway and 39 more60 min

Nearby

Tornado Watches in Indiana, 2015Tornado Watches in Illinois, 2015Tornado Watches in Missouri, 2015Every tornado watch in 2015

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.