Alert archive / Iowa / Tornado Watches in 2016
Tornado Watch 484
The Storm Prediction Center issued this tornado watch at Sep 19, 2016, 2:55 PM CDT for Jo Daviess County, Rock Island County, Illinois; 30 counties in Iowa. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Sep 19, 2016, 2:55 PM CDT (19:55 UTC)
- Expired
- Sep 19, 2016, 7:07 PM CDT
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2.5 in
- Strongest gust expected
- 60 kt
All 32 counties
Appanoose County, IA, Benton County, IA, Buchanan County, IA, Cedar County, IA, Clinton County, IA, Davis County, IA, Delaware County, IA, Dubuque County, IA, Henry County, IA, Iowa County, IA, Jackson County, IA, Jasper County, IA, Jefferson County, IA, Johnson County, IA, Jones County, IA, Keokuk County, IA, Linn County, IA, Louisa County, IA, Lucas County, IA, Mahaska County, IA, Marion County, IA, Marshall County, IA, Monroe County, IA, Muscatine County, IA, Poweshiek County, IA, Scott County, IA, Tama County, IA, Wapello County, IA, Washington County, IA, Wayne County, IA, Jo Daviess County, IL, Rock Island County, IL
The radar
The Des Moines radar (KDMX), 128 km from the middle of the area, began a volume at 19:56 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
- 10%
- 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
- 80%
Warnings issued inside it
4 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 19, 4:35 PM CDT | Severe Thunderstorm Warning | DMX | Jasper, Mahaska, Marion, Poweshiek | 40 min |
| Sep 19, 5:06 PM CDT | Severe Thunderstorm Warning | DMX | Lucas, Monroe | 39 min |
| Sep 19, 5:42 PM CDT | Severe Thunderstorm Warning | DMX | Appanoose, Lucas, Monroe, Wayne | 48 min |
| Sep 19, 6:20 PM CDT | Severe Thunderstorm Warning | DMX | Appanoose, Wayne | 40 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
Davenport, (KDVN), launched 12:00Z, 7.9 hours before the alert went out and 142 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1974 m above ground
- 0-6 km bulk shear
- 30 kt
- 0-1 km storm-relative helicity
- 117 m²/s²
- 0-3 km storm-relative helicity
- 125 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
922
WWUS20 KWNS 191953
SEL4
SPC WW 191953
IAZ000-ILZ000-200300-
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 484
NWS STORM PREDICTION CENTER NORMAN OK
255 PM CDT MON SEP 19 2016
THE NWS STORM PREDICTION CENTER HAS ISSUED A
* TORNADO WATCH FOR PORTIONS OF
PARTS OF EAST CENTRAL AND SOUTHEAST IOWA
EXTREME NORTHWEST ILLINOIS
* EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 255 PM UNTIL
1000 PM CDT.
* PRIMARY THREATS INCLUDE...
A COUPLE TORNADOES POSSIBLE
SCATTERED LARGE HAIL AND ISOLATED VERY LARGE HAIL EVENTS TO 2.5
INCHES IN DIAMETER POSSIBLE
ISOLATED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE
SUMMARY...THUNDERSTORM DEVELOPMENT IS EXPECTED SOON ALONG A COLD
FRONT MOVING SOUTHEASTWARD ACROSS CENTRAL IOWA. THE STORM
ENVIRONMENT HAS BECOME FAVORABLE FOR SUPERCELLS AND STORMS ARE
EXPECTED TO MAINTAIN SOME DISCRETE CHARACTER THROUGH MUCH OF THE
AFTERNOON/EVENING. A COUPLE OF TORNADOES AND ISOLATED VERY LARGE
HAIL WILL BE THE MAIN RISKS...ALONG WITH ISOLATED DAMAGING GUSTS.
THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 55 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 25 MILES NORTH NORTHWEST OF
KNOXVILLE IOWA TO 20 MILES NORTH OF MOLINE ILLINOIS. FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU4).
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 483...
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 31025.
...THOMPSONSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 19, 2:02 PM CDT | Mesoscale Discussion | SPC | Carroll, Jo Daviess, Stephenson | 58 min |
| Sep 19, 5:07 PM CDT | Mesoscale Discussion | SPC | Carroll, Henderson, Henry, Jo Daviess, Mercer, Rock Island and 4 more | 113 min |
| Sep 19, 2:31 PM CDT | Severe Thunderstorm Watch | SPC | Clayton | 3 hr |
| Sep 19, 5:47 PM CDT | Mesoscale Discussion | SPC | Appanoose, Davis, Wayne | 118 min |
Nearby
Tornado Watches in Iowa, 2016Tornado Watches in Illinois, 2016Every tornado watch in 2016
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.