Alert archive / Illinois / Tornado Watches in 2010

Tornado Watch 49

April 5, 201034 counties in Illinois; Saint Charles County, Saint Louis County, City of Saint Louis, Missouri

The Storm Prediction Center issued this tornado watch at Apr 5, 2010, 2:51 PM CDT for 34 counties in Illinois; Saint Charles County, Saint Louis County, City of Saint Louis, Missouri. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued
Apr 5, 2010, 2:51 PM CDT (19:51 UTC)
Expired
Apr 5, 2010, 6:41 PM CDT
In force
4 hr
Issued by
the Storm Prediction Center
Largest hail expected
2.5 in
Strongest gust expected
60 kt
All 37 counties

Bond County, IL, Calhoun County, IL, Champaign County, IL, Christian County, IL, Clark County, IL, Clay County, IL, Clinton County, IL, Coles County, IL, Crawford County, IL, Cumberland County, IL, Douglas County, IL, Edgar County, IL, Effingham County, IL, Fayette County, IL, Greene County, IL, Jasper County, IL, Jersey County, IL, Lawrence County, IL, Macon County, IL, Macoupin County, IL, Madison County, IL, Marion County, IL, Monroe County, IL, Montgomery County, IL, Morgan County, IL, Moultrie County, IL, Piatt County, IL, Richland County, IL, Saint Clair County, IL, Sangamon County, IL, Scott County, IL, Shelby County, IL, Vermilion County, IL, Washington County, IL, City of Saint Louis, MO, Saint Charles County, MO, Saint Louis County, MO

The radar

The Lincoln radar (KILX), 86 km from the middle of the area, began a volume at 19:52 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
30%
One or more gusts of 65 knots or more
30%
Ten or more severe hail reports
40%
One or more hailstones of 2 inches or more
30%
Six or more combined severe hail and wind reports
70%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Apr 5, 3:28 PM CDTSevere Thunderstorm WarningLSXMacoupin, Montgomery47 min
Apr 5, 3:43 PM CDTSevere Thunderstorm WarningILXClark, Edgar62 min
Apr 5, 4:09 PM CDTTornado WarningILXClark, Edgar23 min
Apr 5, 4:16 PM CDTTornado WarningLSXFayette, Montgomery32 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, 7.9 hours before the alert went out and 106 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 2010-04-05Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 2010-04-05The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 2 square meters per square second.1939587897Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1087 m above ground
0-6 km bulk shear
52 kt
0-1 km storm-relative helicity
2 m²/s²
0-3 km storm-relative helicity
112 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.

786 
WWUS20 KWNS 051950
SEL9  
SPC WW 051950
ILZ000-MOZ000-060200-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 49
NWS STORM PREDICTION CENTER NORMAN OK
250 PM CDT MON APR 5 2010

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF 

       CENTRAL ILLINOIS
       EAST CENTRAL MISSOURI

EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 250 PM UNTIL 900
PM CDT.

TORNADOES...HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 60 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 20 MILES NORTH NORTHWEST OF
SAINT LOUIS MISSOURI TO 40 MILES EAST OF MATTOON ILLINOIS.  FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU9).

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 48...

DISCUSSION...THUNDERSTORMS ARE INCREASING IN COVERAGE ACROSS CENTRAL
IL...IN VICINITY OF RETREATING SURFACE WARM FRONT.  MODERATE
INSTABILITY AND RATHER WEAK CAP WILL PROMOTE FURTHER INTENSIFICATION
THROUGH THE AFTERNOON AND EARLY EVENING.  FAVORABLE DEEP LAYER
VERTICAL SHEAR SUGGEST SUPERCELL STORM STRUCTURES ARE LIKELY...WITH
THE RISK OF LARGE HAIL AND DAMAGING WINDS.  ISOLATED TORNADOES
CANNOT BE RULED OUT DUE TO PROXIMITY OF WARM FRONT AND MOISTENING
BOUNDARY LAYER.

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.


...HART

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 4, 8:25 PM CDTMesoscale DiscussionSPCCalhoun, Cass, Christian, DeWitt, Greene, Jersey and 10 more65 min
Apr 4, 8:43 PM CDTSevere Thunderstorm WatchSPCBond, Clinton, Fayette, Jersey, Macoupin, Madison and 6 more5 hr
Apr 4, 11:16 PM CDTMesoscale DiscussionSPCCalhoun, Jersey, Macoupin, Madison, Monroe, Saint Clair59 min
Apr 5, 1:56 AM CDTMesoscale DiscussionSPCClinton, Franklin, Jackson, Monroe, Perry, Randolph and 3 more94 min
Apr 5, 11:11 AM CDTMesoscale DiscussionSPCAdams64 min
Apr 5, 12:28 PM CDTMesoscale DiscussionSPCAlexander, Calhoun, Clinton, Edwards, Franklin, Gallatin and 22 more62 min
Apr 5, 5:23 PM CDTMesoscale DiscussionSPCBureau, Carroll, DeKalb, Henry, Jo Daviess, Kendall and 10 more67 min
Apr 5, 5:47 PM CDTMesoscale DiscussionSPCChampaign, Clark, Coles, Douglas, Edgar, Moultrie and 1 more58 min
Apr 5, 6:56 AM CDTMesoscale DiscussionSPCBuchanan, Caldwell, Carroll, Cass, Chariton, Clay and 10 more64 min
Apr 5, 7:14 AM CDTSevere Thunderstorm WatchSPCAndrew, Atchison, Buchanan, Caldwell, Carroll, Cass and 16 more7 hr
Apr 5, 1:29 PM CDTSevere Thunderstorm WatchSPCAdair, Clark, Gentry, Grundy, Harrison, Mercer and 5 more6 hr
Apr 5, 4:04 PM CDTMesoscale DiscussionSPCAdair, Andrew, Atchison, Buchanan, Caldwell, Carroll and 25 more56 min

Nearby

Tornado Watches in Illinois, 2010Tornado Watches in Missouri, 2010Every tornado watch in 2010

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.