Alert archive / Iowa / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 100, NWS Quad Cities, IA

August 6, 2018Henry County, Jefferson County, Iowa

NWS Quad Cities, IA issued this severe thunderstorm warning at Aug 6, 2018, 10:11 PM CDT for Henry County, Jefferson County, Iowa. It was in force for 37 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Aug 6, 2018, 10:11 PM CDT (03:11 UTC)
Expired: Aug 6, 2018, 10:48 PM CDT
In force: 37 min
Issued by: NWS Quad Cities, IA
Area: Storm-based polygon
Hail: 1.0 in
Wind: 50.0 mph

Counties Henry County, IA, Jefferson County, IA

The radar

The Quad Cities radar (KDVN), 118 km from the middle of the area, began a volume at 03:11 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, 3.2 hours before the alert went out and 124 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: 799 J/kg
Mixed-layer CIN: -43 J/kg
Mixed-layer LCL: 786 m above ground
0-6 km bulk shear: 48 kt
0-1 km storm-relative helicity: 79 m²/s²
0-3 km storm-relative helicity: 204 m²/s²
Significant tornado parameter: 0.8
Supercell composite: 4.9

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Quad Cities, IA wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 6, 6:58 PM CDT, 3 hours 13 minutes earlier.

Area forecast discussion, Aug 6, 6:58 PM CDT, 3 hours 13 minutes before

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Hazardous weather outlook, Aug 6, 4:01 AM CDT, 18 hours 10 minutes before

Hazardous Weather Outlook
National Weather Service Quad Cities IA IL
401 AM CDT Mon Aug 6 2018

IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007-
009-015>018-024>026-034-035-MOZ009-010-070915-
Buchanan-Delaware-Dubuque-Benton-Linn-Jones-Jackson-Iowa-Johnson-
Cedar-Clinton-Muscatine-Scott-Keokuk-Washington-Louisa-Jefferson-
Henry IA-Des Moines-Van Buren-Lee-Jo Daviess-Stephenson-Carroll-
Whiteside-Rock Island-Henry IL-Bureau-Putnam-Mercer-Henderson-
Warren-Hancock-McDonough-Scotland-Clark-
401 AM CDT Mon Aug 6 2018

This Hazardous Weather Outlook is for portions of north central
Illinois...northwest Illinois...west central Illinois...east
central Iowa...northeast Iowa...southeast Iowa and northeast
Missouri.

.DAY ONE...TODAY AND TONIGHT

Thunderstorms are forecast across the area through the period,
especially north of I-80 early this morning and south of I-80
later tonight. The main threats with these storms are heavy rain
and flash flooding plus lightning. Severe weather cannot be ruled
out with the potential of damaging winds and hail later this
afternoon through the overnight hours.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

There are low chances for thunderstorms mainly Tuesday and
Thursday, but no hazards are currently expected other than
lightning.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is possible today and tonight. Rainfall reports
are especially appreciated.

Wolf

In the hours before

Local storm report, Aug 6, 6:12 PM CDT, 3 hours 59 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
612 PM CDT MON AUG 6 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0612 PM     HEAVY RAIN       3 ENE MASSBACH          42.27N 90.06W
08/06/2018  M3.00 INCH       JO DAVIESS         IL   TRAINED SPOTTER

            EVENT TOTAL

&&

PETERS

Special weather statement, Aug 6, 6:49 PM CDT, 3 hours 22 minutes before

Special Weather Statement
National Weather Service Quad Cities IA/IL
649 PM CDT MON AUG 6 2018

IAC087-111-177-MOC045-199-070015-
Henry-Van Buren-Lee-Scotland-Clark-
649 PM CDT MON AUG 6 2018

...AN AREA OF STRONG THUNDERSTORMS WILL AFFECT SOUTHWESTERN HENRY...
SOUTHERN VAN BUREN...NORTHWESTERN LEE...NORTHEASTERN SCOTLAND AND
NORTHWESTERN CLARK COUNTIES UNTIL 715 PM CDT...

At 646 PM CDT, doppler radar indicated strong thunderstorms
clustered in southeast Iowa from near Mount Sterling through
Bentonsport to Houghton, moving east around 20 mph.

Pea size hail and heavy rainfall can be expected with these storms.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

LAT...LON 4060 9220 4060 9218 4069 9218 4092 9146
      4049 9143 4050 9222
TIME...MOT...LOC 2346Z 273DEG 23KT 4062 9188

Sheets

Local storm report, Aug 6, 7:01 PM CDT, 3 hours 10 minutes before

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Special weather statement, Aug 6, 7:08 PM CDT, 3 hours 3 minutes before

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Special weather statement, Aug 6, 10:00 PM CDT, 11 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 6, 10:00 PM CDT	Special Weather Statement	DVN	Henry, Jefferson, Van Buren	45 min
Aug 7, 1:28 PM CDT	Special Weather Statement	DVN	Jones	17 min
Aug 7, 5:13 PM CDT	Special Weather Statement	DVN	Benton	32 min
Aug 7, 5:21 PM CDT	Special Weather Statement	DVN	Van Buren	39 min
Aug 7, 5:51 PM CDT	Special Weather Statement	DVN	Benton, Linn	54 min
Aug 7, 12:59 PM CDT	Special Weather Statement	DVN	Whiteside	31 min
Aug 6, 7:08 PM CDT	Special Weather Statement	DVN	Scotland	22 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2018 Every severe thunderstorm warning 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.