Alert archive / Illinois / Tornado Watches in 1999

Tornado Watch 127

April 5, 199915 counties in Illinois; Des Moines County, Louisa County, Muscatine County, Iowa

The Storm Prediction Center issued this tornado watch at Apr 5, 1999, 7:00 PM CDT for 15 counties in Illinois; Des Moines County, Louisa County, Muscatine County, Iowa. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued
Apr 5, 1999, 7:00 PM CDT (00:00 UTC)
Expired
Apr 5, 1999, 11:00 PM CDT
In force
4 hr
Issued by
the Storm Prediction Center

Counties Des Moines County, IA, Louisa County, IA, Muscatine County, IA, Bureau County, IL, Fulton County, IL, Hancock County, IL, Henderson County, IL, Henry County, IL, Knox County, IL, Mason County, IL, McDonough County, IL, Mercer County, IL, Peoria County, IL, Rock Island County, IL, Schuyler County, IL, Stark County, IL, Tazewell County, IL, Warren County, IL

The radar

The Quad Cities radar (KDVN), 74 km from the middle of the area, began a volume at 00:01 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.

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Apr 5, 7:23 PM CDTSevere Thunderstorm WarningILXSchuyler37 min
Apr 5, 8:59 PM CDTSevere Thunderstorm WarningDVNCedar, Jones, Muscatine61 min

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 0.0 hours before the alert went out and 76 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, Davenport, at 00:00Z on 1999-04-06Temperature 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, Davenport, at 00:00Z on 1999-04-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 341 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
749 m above ground
0-6 km bulk shear
69 kt
0-1 km storm-relative helicity
341 m²/s²
0-3 km storm-relative helicity
451 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

Open this sounding in Storm Lab

The text

The text of this product is not in the archive. The NWS text archive before 2002 is incomplete.

Nearby

Tornado Watches in Illinois, 1999Tornado Watches in Iowa, 1999Every tornado watch in 1999

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.