Alert archive / Iowa / Flash Flood Watches in 2018

Flash Flood Watch 9, NWS Quad Cities, IA

September 6, 20188 counties in Iowa; 4 counties in Illinois; Clark County, Scotland County, Missouri

NWS Quad Cities, IA issued this flash flood watch at Sep 6, 2018, 2:38 PM CDT for 8 counties in Iowa; 4 counties in Illinois; Clark County, Scotland County, Missouri. It took effect at Sep 7, 2018, 12:00 AM CDT. It was in force for 27 hr.

The area

The counties it named.

The facts

Issued
Sep 6, 2018, 2:38 PM CDT (19:38 UTC)
In effect from
Sep 7, 2018, 12:00 AM CDT
Expired
Sep 8, 2018, 2:59 AM CDT
In force
27 hr
Issued by
NWS Quad Cities, IA
Flood severity
None

Counties Des Moines County, IA, Henry County, IA, Jefferson County, IA, Keokuk County, IA, Lee County, IA, Louisa County, IA, Van Buren County, IA, Washington County, IA, Hancock County, IL, Henderson County, IL, McDonough County, IL, Warren County, IL, Clark County, MO, Scotland County, MO

The radar

The Quad Cities radar (KDVN), 114 km from the middle of the area, began a volume at 19:40 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

Lincoln, IL (KILX), launched 12:00Z, 7.6 hours before the alert went out and 254 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, Lincoln, IL at 12:00Z on 2018-09-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 188 joules per kilogram.LCLLFCEL10008507005003002001001 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, Lincoln, IL at 12:00Z on 2018-09-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 34 square meters per square second.1939Sfc1 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
188 J/kg
Mixed-layer CIN
-79 J/kg
Mixed-layer LCL
871 m above ground
0-6 km bulk shear
9 kt
0-1 km storm-relative helicity
34 m²/s²
0-3 km storm-relative helicity
65 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash flood watch 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 flash flood watch went out at Sep 6, 1:00 PM CDT, 1 hour 38 minutes earlier.

Area forecast discussion, Sep 6, 1:00 PM CDT, 1 hour 38 minutes before
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Hazardous weather outlook, Sep 6, 8:13 AM CDT, 6 hours 25 minutes before
Hazardous Weather Outlook
National Weather Service Quad Cities IA IL
813 AM CDT Thu Sep 6 2018

IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007-
009-015>018-024>026-034-035-MOZ009-010-071315-
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-
813 AM CDT Thu Sep 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

Periods of rain, locally heavy, can be expected today south of
Highway 30. Due to the very saturated ground, this rainfall may
cause localized flooding.

Area rivers are experiencing flooding. Please see the
latest Flood Statements and Flood Warnings for details.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

Area rivers will continue to experience flooding. Please see the
latest Flood Statements and Flood Warnings for details.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed today or tonight. However,
any reports of flash flooding or new flooding would be appreciated.

Haase

In the hours before

Local storm report, Sep 6, 10:54 AM CDT, 3 hours 44 minutes before
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Local storm report, Sep 6, 11:29 AM CDT, 3 hours 9 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1129 AM CDT THU SEP 6 2018

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

1129 AM     HEAVY RAIN       2 SE KEOSAUQUA AIRPORT  40.72N 91.92W
09/06/2018  M2.50 INCH       VAN BUREN          IA   TRAINED SPOTTER

            24 HOUR TOTAL.

&&
Local storm report, Sep 6, 12:10 PM CDT, 2 hours 28 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1210 PM CDT THU SEP 6 2018

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

1200 PM     HEAVY RAIN       3 WNW MOUNT STERLING    40.64N 91.98W
09/06/2018  M4.50 INCH       VAN BUREN          IA   TRAINED SPOTTER

            CORRECTS PREVIOUS HEAVY RAIN REPORT FROM 3
            WNW MOUNT STERLING. 29 HOUR TOTAL. 1.4
            INCHES 7AM TO 9AM. ANOTHER 1 INCH SINCE 9AM.

&&
Special weather statement, Sep 6, 12:27 PM CDT, 2 hours 11 minutes before
Special Weather Statement
National Weather Service Quad Cities IA IL
1227 PM CDT Thu Sep 6 2018

IAZ089-099-ILZ025-026-034-035-MOZ010-061930-
Des Moines-Lee-Henderson-Warren-Hancock-McDonough-Clark-
Including the cities of Burlington, Fort Madison, Oquawka,
Monmouth, Carthage, Macomb, and Kahoka
1227 PM CDT Thu Sep 6 2018

...Light to Moderate Rain with Localized Flooding Possible
through Early Afternoon...

Light to moderate rain will continue to fall across areas along
and south of a line from Keokuk, to Burlington, to Galesburg
through mid afternoon. Some isolated pockets of heavy rainfall
will still be possible. Portions of this area has already seen
between 2 and 4 inches of rain.

Runoff from additional rain this afternoon, will lead to
localized flooding in low lying areas and along ditches, creeks,
and streams. In addition, ponding or standing water on roadways
will also be possible.

If you are driving and encounter a flooded roadway, turn around
and find another way to reach your destination safely. Most flood
deaths occur in vehicles.

14
Local storm report, Sep 6, 1:01 PM CDT, 1 hour 37 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
101 PM CDT THU SEP 6 2018

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

0100 PM     HEAVY RAIN       NWS DAVENPORT           41.61N 90.58W
09/06/2018  M1.97 INCH       SCOTT              IA   OFFICIAL NWS OBS

            CO-OP OBSERVER STATION DVNI4, NWS DAVENPORT.
            THE DURATION OF THE HEAVY RAIN EVENT WAS 12
            HOURS.

&&
Local storm report, Sep 6, 1:11 PM CDT, 1 hour 27 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
111 PM CDT THU SEP 6 2018

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

1252 PM     HEAVY RAIN       DAVENPORT ARPT          41.61N 90.59W
09/06/2018  M2.16 INCH       SCOTT              IA   ASOS

            ASOS STATION DVN, DAVENPORT ARPT. THE
            DURATION OF THE HEAVY RAIN EVENT WAS 12
            HOURS.

1253 PM     HEAVY RAIN       BURLINGTON ARPT         40.78N 91.13W
09/06/2018  M1.42 INCH       DES MOINES         IA   ASOS

            ASOS STATION BRL, BURLINGTON ARPT. THE
            DURATION OF THE HEAVY RAIN EVENT WAS 12
            HOURS.

&&

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 6, 7:51 AM CDTSpecial Weather StatementDVNScott114 min
Sep 6, 9:02 AM CDTRiver Flood WarningDVNDes Moines, Henry, Lee8 days
Sep 6, 1:44 PM CDTRiver Flood WarningDVNLee49 hr
Sep 6, 9:49 AM CDTRiver Flood WarningDVNHancock, McDonough47 hr
Sep 6, 4:25 PM CDTRiver Flood WarningDVNClark46 hr

Nearby

Flash Flood Watches in Iowa, 2018Flash Flood Watches in Illinois, 2018Flash Flood Watches in Missouri, 2018Every flash flood watch 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.