Alert archive / Illinois / Flash Flood Watches in 2018

Flash Flood Watch 12, NWS Quad Cities, IA

October 9, 20189 counties in Iowa; 13 counties in Illinois; Clark County, Scotland County, Missouri

NWS Quad Cities, IA issued this flash flood watch at Oct 9, 2018, 3:42 AM CDT for 9 counties in Iowa; 13 counties in Illinois; Clark County, Scotland County, Missouri. It took effect at Oct 9, 2018, 7:00 PM CDT. It was in force for 18 hr.

The area

The counties it named.

The facts

Issued
Oct 9, 2018, 3:42 AM CDT (08:42 UTC)
In effect from
Oct 9, 2018, 7:00 PM CDT
Expired
Oct 10, 2018, 1:00 PM CDT
In force
18 hr
Issued by
NWS Quad Cities, IA
Flood severity
None
All 24 counties

Clinton County, IA, Des Moines County, IA, Henry County, IA, Jackson County, IA, Lee County, IA, Louisa County, IA, Muscatine County, IA, Scott County, IA, Van Buren County, IA, Bureau County, IL, Carroll County, IL, Hancock County, IL, Henderson County, IL, Henry County, IL, Jo Daviess County, IL, McDonough County, IL, Mercer County, IL, Putnam County, IL, Rock Island County, IL, Stephenson County, IL, Warren County, IL, Whiteside County, IL, Clark County, MO, Scotland County, MO

The radar

The Quad Cities radar (KDVN), 41 km from the middle of the area, began a volume at 08:44 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, 8.7 hours before the alert went out and 44 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 2018-10-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 316 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, Davenport, at 00:00Z on 2018-10-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 113 square meters per square second.193958Sfc1 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
316 J/kg
Mixed-layer CIN
-17 J/kg
Mixed-layer LCL
1260 m above ground
0-6 km bulk shear
34 kt
0-1 km storm-relative helicity
113 m²/s²
0-3 km storm-relative helicity
133 m²/s²
Significant tornado parameter
0.1
Supercell composite
2.2

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 Oct 9, 12:46 AM CDT, 2 hours 56 minutes earlier.

Area forecast discussion, Oct 9, 12:46 AM CDT, 2 hours 56 minutes before
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Hazardous weather outlook, Oct 8, 4:43 PM CDT, 10 hours 59 minutes before
Hazardous Weather Outlook
National Weather Service Quad Cities IA IL
443 PM CDT Mon Oct 8 2018

IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007-
009-015>018-024>026-034-035-MOZ009-010-091000-
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-
443 PM CDT Mon Oct 8 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...TONIGHT

Isolated to scattered showers and thunderstorms this evening may
increase in coverage overnight especially west of the Mississippi
River. The primary threat is expected to be heavy rainfall, which
could lead to flash flooding mainly west of a line from Dubuque,
Iowa to Fairfield, Iowa. A Flash Flood Watch remains in affect for
these areas through early Tuesday afternoon. Besides the flooding
threat, an isolated severe storm is also possible in this same
general area this evening and overnight. The primary threat is
damaging winds, with an isolated tornado possible.

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

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

Heavy rainfall is possible over portions of eastern Iowa on Tuesday,
and over the entire outlook area Tuesday night into Wednesday
morning ahead of a strong cold front. An additional 1 to 2 inches
of rainfall and locally higher amounts during this time on
saturated grounds, will aggravate ongoing flooding situations or
create new ones. A Flash Flood Watch may eventually be needed for
Tuesday night into Wednesday.

A few severe storms are also possible Tuesday evening and
overnight, and the Storm Prediction Center has placed much of the
area in a slight risk for severe weather. The primary threat is
damaging winds, with an isolated tornado possible.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is possible for portions of the outlook area
tonight, and again by Tuesday evening. Reports of any flash
flooding would also be appreciated.

12

In the hours before

Special weather statement, Oct 9, 2:27 AM CDT, 1 hour 15 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
Oct 8, 7:45 PM CDTSpecial Weather StatementDVNBenton, Buchanan, Delaware, Linn90 min
Oct 8, 8:20 PM CDTTornado WarningDVNKeokuk29 min
Oct 8, 9:23 PM CDTSpecial Weather StatementDVNBuchanan, Delaware82 min
Oct 8, 10:29 PM CDTSevere Thunderstorm WarningDVNBenton, Iowa46 min
Oct 9, 2:27 AM CDTSpecial Weather StatementDVNBenton, Buchanan63 min
Oct 9, 11:23 AM CDTRiver Flood WarningDVNBuchanan, Linn5 days
Oct 9, 11:26 AM CDTRiver Flood WarningDVNDelaware, Jones3 days
Oct 9, 12:45 PM CDTRiver Flood WarningDVNDubuque, Jackson6 days
Oct 9, 1:31 PM CDTRiver Flood WarningDVNDubuque16 days
Oct 9, 2:12 PM CDTTornado WarningDVNDubuque48 min
Oct 9, 3:06 PM CDTTornado WarningDVNBenton, Iowa39 min
Oct 9, 3:09 PM CDTTornado WarningDVNDelaware51 min
Oct 9, 3:38 PM CDTTornado WarningDVNBenton, Iowa52 min
Oct 9, 4:03 PM CDTTornado WarningDVNIowa, Keokuk, Washington27 min
Oct 9, 4:31 PM CDTTornado WarningDVNIowa, Johnson44 min
Oct 9, 5:14 PM CDTTornado WarningDVNBenton, Iowa, Johnson, Linn46 min
Oct 9, 5:51 PM CDTTornado WarningDVNLinn24 min

Nearby

Flash Flood Watches in Illinois, 2018Flash Flood Watches in Iowa, 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.