Alert archive / Illinois / Severe Thunderstorm Watches in 2008
Severe Thunderstorm Watch 721
The Storm Prediction Center issued this severe thunderstorm watch at Jul 21, 2008, 9:14 PM CDT for 28 counties in Illinois; 6 counties in Indiana; 16 counties in Missouri. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 21, 2008, 9:14 PM CDT (02:14 UTC)
- Expired
- Jul 22, 2008, 3:00 AM CDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2.5 in
- Strongest gust expected
- 60 kt
All 50 counties
Bond County, IL, Calhoun County, IL, Clay County, IL, Clinton County, IL, Crawford County, IL, Edwards County, IL, Effingham County, IL, Fayette County, IL, Franklin County, IL, Greene County, IL, Hamilton County, IL, Jasper County, IL, Jefferson County, IL, Jersey County, IL, Lawrence County, IL, Macoupin County, IL, Madison County, IL, Marion County, IL, Monroe County, IL, Montgomery County, IL, Perry County, IL, Randolph County, IL, Richland County, IL, Saint Clair County, IL, Wabash County, IL, Washington County, IL, Wayne County, IL, White County, IL, Gibson County, IN, Pike County, IN, Posey County, IN, Spencer County, IN, Vanderburgh County, IN, Warrick County, IN, Audrain County, MO, Boone County, MO, Callaway County, MO, City of Saint Louis, MO, Cole County, MO, Franklin County, MO, Gasconade County, MO, Jefferson County, MO, Lincoln County, MO, Moniteau County, MO, Montgomery County, MO, Osage County, MO, Pike County, MO, Saint Charles County, MO, Saint Louis County, MO, Warren County, MO
The radar
The St Louis radar (KLSX), 33 km from the middle of the area, began a volume at 02:14 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
- 10%
- One or more EF2 to EF5 tornadoes
- 5%
- Ten or more severe wind reports
- 50%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 50%
- One or more hailstones of 2 inches or more
- 40%
- Six or more combined severe hail and wind reports
- 90%
Warnings issued inside it
7 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 21, 9:31 PM CDT | Severe Thunderstorm Warning | LSX | Audrain, Marion, Monroe, Pike, Ralls | 44 min |
| Jul 21, 10:10 PM CDT | Severe Thunderstorm Warning | LSX | Audrain, Monroe, Ralls | 21 min |
| Jul 21, 10:46 PM CDT | Severe Thunderstorm Warning | LSX | Calhoun, Greene, Jersey | 50 min |
| Jul 21, 11:24 PM CDT | Severe Thunderstorm Warning | LSX | Audrain, Monroe | 51 min |
| Jul 21, 11:48 PM CDT | Severe Thunderstorm Warning | LSX | Saint Charles, Saint Louis, City of Saint Louis | 42 min |
| Jul 21, 11:53 PM CDT | Severe Thunderstorm Warning | LSX | Madison | 46 min |
| Jul 22, 12:16 AM CDT | Severe Thunderstorm Warning | LSX | Audrain, Lincoln, Montgomery, Pike | 44 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 00:00Z, 2.2 hours before the alert went out and 209 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.
- Mixed-layer CAPE
- 3634 J/kg
- Mixed-layer CIN
- -9 J/kg
- Mixed-layer LCL
- 1043 m above ground
- 0-6 km bulk shear
- 39 kt
- 0-1 km storm-relative helicity
- 90 m²/s²
- 0-3 km storm-relative helicity
- 147 m²/s²
- Significant tornado parameter
- 3.2
- Supercell composite
- 17.9
The text
As transmitted, in the capitals the NWS used until 2016.
000
WWUS20 KWNS 220215
SEL1
SPC WW 220215
ILZ000-INZ000-MOZ000-220800-
URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 721
NWS STORM PREDICTION CENTER NORMAN OK
915 PM CDT MON JUL 21 2008
THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
SOUTHERN ILLINOIS
SOUTHWEST INDIANA
CENTRAL AND EASTERN MISSOURI
EFFECTIVE THIS MONDAY NIGHT AND TUESDAY MORNING FROM 915 PM UNTIL
300 AM CDT.
HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 50
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 25 MILES WEST OF
COLUMBIA MISSOURI TO 50 MILES NORTHEAST OF EVANSVILLE INDIANA.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU1).
REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR 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. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.
OTHER WATCH INFORMATION...CONTINUE...WW 719...WW 720...
DISCUSSION...LINEAR MCS WILL CONTINUE TO SAG SSEWD ACROSS THIS
REGION TONIGHT AND FEED OF A VERY UNSTABLE AIR MASS IN PLACE
REPRESENTED BY MLCAPE IN EXCESS OF 4000 J/KG AT MID EVENING.
COMBINED WITH 30-40 KT DEEP LAYER SHEAR...THIS WILL PROVE MORE THAN
ADEQUATE FOR THREATS OF LARGE HAIL AND DAMAGING WINDS. ORGANIZATION
INTO ONE OR MORE BOWING MCSS ALSO REMAINS POSSIBLE LATE THIS
EVENING.
AVIATION...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 550. MEAN STORM
MOTION VECTOR 34025.
...EVANSSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 21, 7:16 PM CDT | Mesoscale Discussion | SPC | Adams, Brown, Cass, Fulton, Hancock, McDonough and 6 more | 89 min |
| Jul 21, 7:20 PM CDT | Severe Thunderstorm Watch | SPC | Cass, Champaign, Christian, Clark, Coles, Cumberland and 26 more | 7 hr |
| Jul 21, 8:00 PM CDT | Mesoscale Discussion | SPC | Bond, Calhoun, Christian, Clay, Clinton, Effingham and 12 more | 90 min |
| Jul 21, 10:38 PM CDT | Mesoscale Discussion | SPC | Bond, Calhoun, Christian, Clark, Clay, Clinton and 32 more | 97 min |
| Jul 22, 4:47 AM CDT | Mesoscale Discussion | SPC | Alexander, Hardin, Jackson, Johnson, Massac, Pope and 5 more | 88 min |
| Jul 21, 11:06 PM CDT | Severe Thunderstorm Watch | SPC | Clark, Crawford, Dearborn, Dubois, Fayette, Floyd and 12 more | 6 hr |
| Jul 22, 1:21 AM CDT | Mesoscale Discussion | SPC | Clark, Crawford, Dearborn, Dubois, Fayette, Floyd and 11 more | 54 min |
| Jul 22, 3:18 AM CDT | Mesoscale Discussion | SPC | Adair, Andrew, Atchison, Audrain, Buchanan, Caldwell and 23 more | 87 min |
| Jul 22, 9:34 AM CDT | Mesoscale Discussion | SPC | Boone, Camden, Cole, Cooper, Crawford, Dent and 12 more | 56 min |
| Jul 22, 11:55 AM CDT | Mesoscale Discussion | SPC | Dunklin, Pemiscot | 3 hr |
| Jul 22, 2:25 PM CDT | Mesoscale Discussion | SPC | Barry, Butler, Carter, Howell, Jasper, McDonald and 7 more | 2 hr |
Nearby
Severe Thunderstorm Watches in Illinois, 2008Severe Thunderstorm Watches in Missouri, 2008Severe Thunderstorm Watches in Indiana, 2008Every severe thunderstorm watch in 2008
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.