Alert archive / Illinois / Tornado Warnings in 2018

Tornado Warning 19, NWS Quad Cities, IA

August 16, 2018Stephenson County, Illinois

NWS Quad Cities, IA issued this tornado warning at Aug 16, 2018, 8:27 PM CDT for Stephenson County, Illinois. It was in force for 18 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Aug 16, 2018, 8:27 PM CDT (01:27 UTC)
Expired: Aug 16, 2018, 8:45 PM CDT
In force: 18 min
Issued by: NWS Quad Cities, IA
Area: Storm-based polygon
Tornado: Observed
Hail: 0.75 in

County Stephenson County, IL

The radar

The Quad Cities radar (KDVN), 111 km from the middle of the area, began a volume at 01:27 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.

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 1.5 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 1949 J/kg
Mixed-layer CIN: -2 J/kg
Mixed-layer LCL: 837 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 30 m²/s²
0-3 km storm-relative helicity: 57 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 2.6

Open this sounding in Storm Lab

The text

As transmitted.

295 
WFUS53 KDVN 170127
TORDVN
ILC177-170145-
/O.NEW.KDVN.TO.W.0019.180817T0127Z-180817T0145Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Quad Cities IA/IL
827 PM CDT THU AUG 16 2018

The National Weather Service in the Quad Cities has issued a

* Tornado Warning for...
  Central Stephenson County in northwestern Illinois...

* Until 845 PM CDT.

* At 826 PM CDT, a confirmed tornado was located near Lena, or near
  Freeport, moving northeast at 15 mph.

  HAZARD...Damaging tornado.

  SOURCE...Law enforcement confirmed tornado.

  IMPACT...Flying debris will be dangerous to those caught without 
           shelter. Mobile homes will be damaged or destroyed. 
           Damage to roofs, windows, and vehicles will occur.  Tree 
           damage is likely.

* The tornado will be near...
  Freeport around 835 PM CDT.
  Cedarville around 845 PM CDT.

Other locations impacted by this tornadic thunderstorm include
Eleroy, Scioto Mills, Red Oak, Dakota Dornink Airport, Damascus,
Buena Vista, Mc Connell and Bolton.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

To repeat, a tornado is on the ground. TAKE COVER NOW! Move to a
basement or an interior room on the lowest floor of a sturdy
building. Avoid windows. If you are outdoors, in a mobile home, or in
a vehicle, move to the closest substantial shelter and protect
yourself from flying debris.

&&

LAT...LON 4238 8951 4224 8975 4230 8987 4248 8975
TIME...MOT...LOC 0126Z 214DEG 15KT 4234 8975 

TORNADO...OBSERVED
HAIL...<.75IN

$$

Gibbs

1 follow-up statement

078 
WWUS53 KDVN 170136
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
836 PM CDT THU AUG 16 2018

ILC177-170145-
/O.EXP.KDVN.TO.W.0019.000000T0000Z-180817T0145Z/
Stephenson IL-
836 PM CDT THU AUG 16 2018

...THE TORNADO WARNING FOR CENTRAL STEPHENSON COUNTY WILL EXPIRE AT
845 PM CDT...
                
The storm which prompted the warning has weakened below severe
limits, and no longer appears capable of producing a tornado.
Therefore, the warning will be allowed to expire.  However heavy rain
is still possible with this thunderstorm.

LAT...LON 4238 8951 4224 8975 4230 8987 4248 8975
TIME...MOT...LOC 0135Z 214DEG 15KT 4236 8973 

$$

Gibbs

The office that day

Everything else NWS Quad Cities, IA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 16, 7:21 PM CDT	Special Weather Statement	DVN	Rock Island	24 min
Aug 16, 7:54 PM CDT	Special Weather Statement	DVN	McDonough	21 min
Aug 16, 7:55 PM CDT	Special Weather Statement	DVN	Stephenson	80 min
Aug 16, 10:06 PM CDT	Special Weather Statement	DVN	Putnam	24 min
Aug 17, 1:07 AM CDT	Special Weather Statement	DVN	Hancock	38 min
Aug 17, 6:41 AM CDT	Dense Fog Advisory	DVN	Rock Island	2 hr

Nearby

Tornado Warnings in Illinois, 2018 Every tornado warning in 2018 Tornadoes in 2018

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.