Alert archive / Iowa / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 95, NWS Quad Cities, IA

July 19, 2018Lee County, Iowa; Clark County, Missouri

NWS Quad Cities, IA issued this severe thunderstorm warning at Jul 19, 2018, 8:06 PM CDT for Lee County, Iowa; Clark County, Missouri. It was in force for 39 min. 2 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Jul 19, 2018, 8:06 PM CDT (01:06 UTC)
Expired: Jul 19, 2018, 8:45 PM CDT
In force: 39 min
Issued by: NWS Quad Cities, IA
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Lee County, IA, Clark County, MO

The radar

The Quad Cities radar (KDVN), 164 km from the middle of the area, began a volume at 01:09 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 was reported inside it

Time	Report	Where	Remark
Jul 19, 8:08 PM CDT	TSTM WND DMG	Wyaconda, MO	TREE DOWN IN WYACONDA ON RTE A.
Jul 19, 8:18 PM CDT	HAIL 0.25	2 N Kahoka, MO	PEA HAIL OCCURRING RIGHT NOW.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

Did it verify

Verified. The Iowa Environmental Mesonet's Cow matched one storm report to this severe thunderstorm warning; the first came 2 minutes after it went out.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Jul 19, 3:11 PM CDT	Tornado Watch	SPC	6 hr

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 1.1 hours before the alert went out and 169 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: 1195 J/kg
Mixed-layer CIN: -65 J/kg
Mixed-layer LCL: 653 m above ground
0-6 km bulk shear: 35 kt
0-1 km storm-relative helicity: 291 m²/s²
0-3 km storm-relative helicity: 344 m²/s²
Significant tornado parameter: 1.3
Supercell composite: 8.1

Open this sounding in Storm Lab

The text

As transmitted.

496 
WUUS53 KDVN 200106
SVRDVN
IAC111-MOC045-200145-
/O.NEW.KDVN.SV.W.0095.180720T0106Z-180720T0145Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Quad Cities IA/IL
806 PM CDT THU JUL 19 2018

The National Weather Service in the Quad Cities has issued a

* Severe Thunderstorm Warning for...
  Southwestern Lee County in southeastern Iowa...
  Central Clark County in northeastern Missouri...

* Until 845 PM CDT.

* At 805 PM CDT, a severe thunderstorm was located over Luray, or 7
  miles northwest of Kahoka, moving east at 25 mph.

  HAZARD...60 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Hail damage to vehicles is expected. Expect wind damage 
           to roofs, siding, and trees.

* Locations impacted include...
  Kahoka, Wayland, Wyaconda, Luray, St. Francisville, Revere, Clark
  County Fairgrounds, Chambersburg, Ashton, Vincennes, Peaksville,
  Clark City, Medill and Argyle.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
sturdy building.

&&

A Tornado Watch remains in effect until 1000 PM CDT for southeastern
Iowa...and northeastern Missouri.

LAT...LON 4039 9194 4054 9192 4055 9150 4032 9155
TIME...MOT...LOC 0105Z 277DEG 20KT 4047 9184 

HAIL...1.00IN
WIND...60MPH
 
$$

Speck

2 follow-up statements

822 
WWUS53 KDVN 200125
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
825 PM CDT THU JUL 19 2018

IAC111-200134-
/O.CAN.KDVN.SV.W.0095.000000T0000Z-180720T0145Z/
Lee IA-
825 PM CDT THU JUL 19 2018

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHWESTERN LEE COUNTY IS
CANCELLED...
    
The severe thunderstorm which prompted the warning has moved out of 
the warned area. Therefore, the warning has been cancelled.

A Tornado Watch remains in effect until 1000 PM CDT for southeastern
Iowa...and northeastern Missouri.

LAT...LON 4039 9194 4054 9192 4053 9162 4051 9162
      4049 9159 4047 9158 4046 9156 4046 9153
      4032 9155
TIME...MOT...LOC 0124Z 290DEG 28KT 4040 9168 

$$

MOC045-200145-
/O.CON.KDVN.SV.W.0095.000000T0000Z-180720T0145Z/
Clark MO-
825 PM CDT THU JUL 19 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 845 PM CDT
FOR CENTRAL CLARK COUNTY...

At 824 PM CDT, a severe thunderstorm was located over Kahoka, moving
east at 30 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

Locations impacted include...
Kahoka, Wayland, Wyaconda, Luray, St. Francisville, Revere,
Peaksville, Clark City, Clark County Fairgrounds, Chambersburg,
Ashton and Medill.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
sturdy building.

&&

A Tornado Watch remains in effect until 1000 PM CDT for southeastern
Iowa...and northeastern Missouri.

LAT...LON 4039 9194 4054 9192 4053 9162 4051 9162
      4049 9159 4047 9158 4046 9156 4046 9153
      4032 9155
TIME...MOT...LOC 0124Z 290DEG 28KT 4040 9168 

HAIL...1.00IN
WIND...60MPH
 
$$

Speck

456 
WWUS53 KDVN 200144
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
844 PM CDT THU JUL 19 2018

MOC045-200154-
/O.EXP.KDVN.SV.W.0095.000000T0000Z-180720T0145Z/
Clark MO-
844 PM CDT THU JUL 19 2018

...THE SEVERE THUNDERSTORM WARNING FOR CENTRAL CLARK COUNTY WILL
EXPIRE AT 845 PM CDT...
        
The storm which prompted the warning has weakened below severe
limits, and has exited the warned area. Therefore, the warning will
be allowed to expire.  However small hail and gusty winds are still
possible with this thunderstorm.

A Tornado Watch remains in effect until 1000 PM CDT for southeastern
Iowa...and northeastern Missouri.

LAT...LON 4039 9194 4054 9192 4053 9162 4051 9162
      4049 9159 4047 9158 4046 9156 4046 9153
      4032 9155
TIME...MOT...LOC 0144Z 277DEG 20KT 4039 9155 

$$

Speck

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 Jul 19, 6:33 PM CDT, 1 hour 33 minutes earlier.

Area forecast discussion, Jul 19, 6:33 PM CDT, 1 hour 33 minutes before

Area Forecast Discussion
National Weather Service Quad Cities IA IL
633 PM CDT Thu Jul 19 2018

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 211 PM CDT Thu Jul 19 2018

The elevated showers and thunderstorms have now pushed east towards
northeast Illinois, with increasing temperatures, increasing
dewpoints, and increasing southeast winds behind them. It appears
that we will have sufficient CAPE and convergence for another round
of storms over the area this afternoon and evening. Shear will be
conducive for rotating updrafts, and bowing line segments.

&&

.SHORT TERM...(This Evening through Friday)
ISSUED AT 211 PM CDT Thu Jul 19 2018

The evening storms should initially be lined up along the cold
front, though some additional overnight activity may be in narrow
bands of showers and storms.  Rainfall over 1 inch will certainly be
possible in any storm tonight, and any repeat storms certainly could
bring 2 inches. Amount similar to that already fell this morning.
Shear supports rotating storms with 20 to 25 kts of surface to 1 Km
shear, and 40 kts of deep layer shear. Thus, supercells are likely,
with bowing line segments in mature linear convection as well.
This event will likely come in two bands. The first seems to
already forming in out northwest, the other near I-35 as of 2 PM.
More an more, I believe that the first of these waves will be the
main evening event. We will watch this, and begin issuing products
specifically above this line soon.

Overnight, the activity should become less intense, though some
small hail will be possible as the cooler air aloft arrives
overnight when the upper low nears the area. That upper low should
at least support showers and a few brief storms through the day
Friday, mainly in the northeast.

Temperatures are a struggle, as we have hot air to the southwest,
and warmer air to the east, and rain cooled air in place, which is
slowly warming.  We'll stay close to models on lows and highs, and
go with mid to upper 60s tonight, followed by mid 70s north to lower
80s south Friday.

.LONG TERM...(Friday Night through Thursday)
ISSUED AT 211 PM CDT Thu Jul 19 2018

Little change to the long term forecast as a slow moving vertically
stacked system will lumber east.  With cold air aloft over the area,
daytime heating could lead to showers and isolated thunderstorms,
especially across eastern areas.  This will continue until the low
finally moves east of the area.  Overall the pattern is such that
cooler and drier air is expected this weekend across most of the
area.  Sunday, the chance for isolated showers and storms will be
across Bureau and Putnam counties, otherwise the rest of the area
should be quiet.

Into next week, the current forecast has dewpoints returning to the
60s, but no 70 degree dewpoints.  While the air will become more
moist, from a sensible weather point of view it should be typical
summer with slighly drier air with temps in the 80s and lows in the
60s at night.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday Evening)
ISSUED AT 630 PM CDT Thu Jul 19 2018

Isolated storms to end by 20/03Z with partly cloudy skies, VFR conditions
and gusty NW winds through the next 24 hours as storm system moves to
the east. Any cloud bases later tonight and Friday will be 3-5K AGL.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.

&&

SYNOPSIS...Ervin
SHORT TERM...Ervin
LONG TERM...Gibbs
AVIATION...16

Hazardous weather outlook, Jul 19, 4:11 AM CDT, 15 hours 55 minutes before

Hazardous Weather Outlook
National Weather Service Quad Cities IA IL
411 AM CDT Thu Jul 19 2018

IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007-
009-015>018-024>026-034-035-MOZ009-010-200915-
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-
411 AM CDT Thu Jul 19 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

Slow moving thunderstorms with heavy rainfall may lead to minor
flooding over portions of east central Iowa this morning.
Scattered thunderstorms will affect much of the outlook area
through the day with locally heavy rainfall and cloud to ground
lightning the primary threats.

Severe storms will be possible from late afternoon through this
evening. The Storm Prediction Center has a Slight Risk west of a
line from Independence through Muscatine, Iowa to Macomb,
Illinois. A Marginal Risk is in place for the remainder of the
outlook area. The main severe risk threats will be damaging wind
and large hail. An isolated tornado is possible.

Widespread rain and thunderstorms are expected to continue
overnight over east central Iowa into northwest Illinois. Severe
weather is not expected, but there will continue to be a threat of
locally heavy rainfall.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

Thunderstorms are expected again Friday. Severe weather is not
expected.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed this afternoon and this evening.

Sheets

In the hours before

Local storm report, Jul 19, 7:34 PM CDT, 32 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
734 PM CDT THU JUL 19 2018

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

0639 PM     TSTM WND DMG     CROTON                  40.59N 91.68W
07/19/2018                   LEE                IA   TRAINED SPOTTER

            DELAYED REPORT AND TIME ESTIMATED FROM
            RADAR. NUMEROUS TREES DOWN.

&&

Local storm report, Jul 19, 7:45 PM CDT, 21 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
745 PM CDT THU JUL 19 2018

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

0650 PM     TSTM WND DMG     1 NW FROST ISLAND CA    40.45N 91.57W
07/19/2018                   CLARK              MO   EMERGENCY MNGR

            REPORT OF POWER LINES DOWN WITH TREE
            BRANCHES IN ST. FRANCISVILLE, MO. TIME
            ESTIMATED BASED ON RADAR.

&&

PS

Local storm report, Jul 19, 7:50 PM CDT, 16 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
750 PM CDT THU JUL 19 2018

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

0609 PM     TSTM WND DMG     1 NW KEOSAUQUA AIRPORT  40.75N 91.96W
07/19/2018                   VAN BUREN          IA   EMERGENCY MNGR

            DELAYED REPORT AND TIME ESTIMATED FROM
            RADAR. CONSIDERABLE DAMAGE TO BUILDINGS AT
            THE FAIRGROUNDS. GAS PUMPS BLOWN OVER AND A
            BUILDING DAMAGED AT A COUNTY FACILITY NEXT
            TO THE FAIRGROUNDS.

&&

Local storm report, Jul 19, 7:53 PM CDT, 13 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
753 PM CDT THU JUL 19 2018

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

0715 PM     TSTM WND DMG     MOOAR                   40.44N 91.45W
07/19/2018                   LEE                IA   PUBLIC

            SEVERAL TRREES AND LARGE TREE BRANCHEWS DOWN
            AT KEOKUK HIGH SCHOOL. TIME ESTIMATED BY
            RADAR.

&&

Local storm report, Jul 19, 7:58 PM CDT, 8 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
758 PM CDT THU JUL 19 2018

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

0758 PM     TSTM WND GST     SHANNON                 42.15N 89.74W
07/19/2018  M60 MPH          CARROLL            IL   TRAINED SPOTTER

&&

PS

Local storm report, Jul 19, 7:59 PM CDT, 7 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
759 PM CDT THU JUL 19 2018

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

0715 PM     TSTM WND DMG     MOOAR                   40.44N 91.45W
07/19/2018                   LEE                IA   PUBLIC

            CORRECTS PREVIOUS TSTM WND DMG REPORT FROM
            MOOAR. SEVERAL TREES AND LARGE TREE BRANCHES
            DOWN AT KEOKUK HIGH SCHOOL. TIME ESTIMATED
            BY RADAR.

&&

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 19, 7:20 PM CDT	Severe Thunderstorm Warning	DVN	Clark, Scotland	40 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2018 Severe Thunderstorm Warnings in Missouri, 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.