Alert archive / Iowa / Flash Flood Watches in 2019

Flash Flood Watch 3, NWS Des Moines, IA

May 18, 201930 counties in Iowa

NWS Des Moines, IA issued this flash flood watch at May 18, 2019, 3:59 AM CDT for 30 counties in Iowa. It took effect at May 18, 2019, 4:00 PM CDT. It was in force for 9 hr.

The area

The counties it named.

The facts

Issued
May 18, 2019, 3:59 AM CDT (08:59 UTC)
In effect from
May 18, 2019, 4:00 PM CDT
Expired
May 19, 2019, 1:00 AM CDT
In force
9 hr
Issued by
NWS Des Moines, IA
Flood severity
None
All 30 counties

Adair County, IA, Adams County, IA, Appanoose County, IA, Audubon County, IA, Black Hawk County, IA, Boone County, IA, Cass County, IA, Clarke County, IA, Dallas County, IA, Davis County, IA, Decatur County, IA, Grundy County, IA, Guthrie County, IA, Jasper County, IA, Lucas County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Marshall County, IA, Monroe County, IA, Polk County, IA, Poweshiek County, IA, Ringgold County, IA, Story County, IA, Tama County, IA, Taylor County, IA, Union County, IA, Wapello County, IA, Warren County, IA, Wayne County, IA

The radar

The Des Moines radar (KDMX), 41 km from the middle of the area, began a volume at 09:02 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

Topeka, KS (KFOE), launched 00:00Z, 9.0 hours before the alert went out and 321 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, Topeka, KS at 00:00Z on 2019-05-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 186 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, Topeka, KS at 00:00Z on 2019-05-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 27 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
186 J/kg
Mixed-layer CIN
-217 J/kg
Mixed-layer LCL
1950 m above ground
0-6 km bulk shear
23 kt
0-1 km storm-relative helicity
27 m²/s²
0-3 km storm-relative helicity
120 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

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 Des Moines, IA wrote its last area forecast discussion before this flash flood watch went out at May 18, 3:44 AM CDT, 15 minutes earlier.

Area forecast discussion, May 18, 3:44 AM CDT, 15 minutes before
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Hazardous weather outlook, May 17, 3:42 PM CDT, 12 hours 17 minutes before
Hazardous Weather Outlook
National Weather Service Des Moines IA
342 PM CDT Fri May 17 2019

IAZ004-182045-
Emmet-
342 PM CDT Fri May 17 2019

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...This afternoon and tonight

A River Flood Warning is in effect for the area. Please refer to
the National Weather Service website at weather.gov/desmoines for
further details.

Showers and thunderstorms are possible this evening and overnight.
A few may become strong to severe with hail and strong winds the
primary threats.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday

More widespread shower and thunderstorm activity is expected to
develop Saturday and continue into Saturday night. The potential
exists for severe thunderstorms capable of producing large hail
and damaging wind gusts. The most favorable period for severe
weather occurs during the afternoon and evening hours. In
addition, heavy rainfall will be possible which could cause
localized flooding concerns.

Another round of thunderstorm activity is forecast for Tuesday
into Tuesday night. Severe weather and heavy rainfall will be
possible, but details remain uncertain at this time.

.SPOTTER INFORMATION STATEMENT...

Spotters may be needed Saturday afternoon and evening.

IAZ005>007-015>017-023>028-033>039-044>050-057>062-182045-
Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo-Pocahontas-
Humboldt-Wright-Franklin-Butler-Bremer-Sac-Calhoun-Webster-
Hamilton-Hardin-Grundy-Black Hawk-Crawford-Carroll-Greene-Boone-
Story-Marshall-Tama-Audubon-Guthrie-Dallas-Polk-Jasper-Poweshiek-
342 PM CDT Fri May 17 2019

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...This afternoon and tonight

Showers and thunderstorms are possible this evening and
overnight. A few may become strong to severe with hail and strong
winds the primary threats.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday

More widespread shower and thunderstorm activity is expected to
develop Saturday and continue into Saturday night. The potential
exists for severe thunderstorms capable of producing large hail
and damaging wind gusts. The most favorable period for severe
weather occurs during the afternoon and evening hours. In
addition, heavy rainfall will be possible which could cause
localized flooding concerns.

Another round of thunderstorm activity is forecast for Tuesday
into Tuesday night. Severe weather and heavy rainfall will be
possible, but details remain uncertain at this time.

.SPOTTER INFORMATION STATEMENT...

Spotters may be needed Saturday afternoon and evening.

IAZ070>075-081>086-092>097-182045-
Cass-Adair-Madison-Warren-Marion-Mahaska-Adams-Union-Clarke-Lucas-
Monroe-Wapello-Taylor-Ringgold-Decatur-Wayne-Appanoose-Davis-
342 PM CDT Fri May 17 2019

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...This afternoon and tonight

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday

More widespread shower and thunderstorm activity is expected to
develop Saturday and continue into Saturday night. The potential
exists for severe thunderstorms capable of producing large hail
and damaging wind gusts. The most favorable period for severe
weather occurs during the afternoon and evening hours. In
addition, heavy rainfall will be possible which could cause
localized flooding concerns.

Another round of thunderstorm activity is forecast for Tuesday
into Tuesday night. Severe weather and heavy rainfall will be
possible, but details remain uncertain at this time.

.SPOTTER INFORMATION STATEMENT...

Spotters may be needed Saturday afternoon and evening.

In the hours before

Special weather statement, May 17, 11:48 PM CDT, 4 hours 11 minutes before
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The office that day

Everything else NWS Des Moines, IA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 17, 7:13 PM CDTSpecial Weather StatementDMXCerro Gordo47 min
May 18, 10:11 AM CDTRiver Flood WatchDMXPolk7 days
May 18, 10:11 AM CDTRiver Flood WatchDMXDavis, Wapello11 hr
May 18, 10:11 AM CDTRiver Flood WatchDMXPolk7 days
May 18, 10:11 AM CDTRiver Flood WatchDMXDallas, Greene5 days
May 18, 3:56 PM CDTSpecial Weather StatementDMXAppanoose19 min
May 18, 4:18 PM CDTSpecial Weather StatementDMXAppanoose, Davis, Lucas, Monroe, Wapello, Wayne42 min
May 18, 5:38 PM CDTSpecial Weather StatementDMXDavis, Wapello52 min
May 18, 6:28 PM CDTSpecial Weather StatementDMXPoweshiek62 min

Nearby

Flash Flood Watches in Iowa, 2019Every flash flood watch in 2019

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.