Alert archive / Iowa / Flash Flood Watches in 2008

Flash Flood Watch 16, NWS Des Moines, IA

July 20, 200831 counties in Iowa

NWS Des Moines, IA issued this flash flood watch at Jul 20, 2008, 3:10 PM CDT for 31 counties in Iowa. It took effect at Jul 20, 2008, 10:00 PM CDT. It was in force for 7 hr.

The area

The counties it named.

The facts

Issued: Jul 20, 2008, 3:10 PM CDT (20:10 UTC)
In effect from: Jul 20, 2008, 10:00 PM CDT
Expired: Jul 21, 2008, 4:44 AM CDT
In force: 7 hr
Issued by: NWS Des Moines, IA
Flood severity: None

All 31 counties

Adair County, IA, Audubon County, IA, Black Hawk County, IA, Boone County, IA, Bremer County, IA, Butler County, IA, Calhoun County, IA, Carroll County, IA, Crawford County, IA, Dallas County, IA, Franklin County, IA, Greene County, IA, Grundy County, IA, Guthrie County, IA, Hamilton County, IA, Hardin County, IA, Humboldt County, IA, Jasper County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Marshall County, IA, Pocahontas County, IA, Polk County, IA, Poweshiek County, IA, Sac County, IA, Story County, IA, Tama County, IA, Warren County, IA, Webster County, IA, Wright County, IA

The radar

The Des Moines radar (KDMX), 39 km from the middle of the area, began a volume at 20:12 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

Omaha, NE (KOAX), launched 12:00Z, 8.2 hours before the alert went out and 237 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: 3469 J/kg
Mixed-layer CIN: -132 J/kg
Mixed-layer LCL: 922 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 23 m²/s²
0-3 km storm-relative helicity: 94 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.3

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 Jul 20, 3:10 PM CDT, 0 minutes earlier.

Area forecast discussion, Jul 20, 3:10 PM CDT, 0 minutes before

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Hazardous weather outlook, Jul 20, 5:55 AM CDT, 9 hours 15 minutes before

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In the hours before

Local storm report, Jul 20, 10:28 AM CDT, 4 hours 42 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 19, 7:02 PM CDT	Severe Thunderstorm Warning	DMX	Franklin, Hamilton, Hardin, Wright	43 min
Jul 19, 7:34 PM CDT	Tornado Warning	DMX	Audubon, Carroll, Guthrie	41 min
Jul 19, 7:38 PM CDT	Severe Thunderstorm Warning	DMX	Calhoun, Greene, Webster	52 min
Jul 19, 7:42 PM CDT	Tornado Warning	DMX	Grundy, Hardin, Marshall	33 min
Jul 19, 7:44 PM CDT	Severe Thunderstorm Warning	DMX	Black Hawk, Bremer, Butler, Grundy, Hardin, Tama	46 min
Jul 19, 8:18 PM CDT	Severe Thunderstorm Warning	DMX	Marshall, Poweshiek, Tama	37 min
Jul 19, 8:26 PM CDT	Tornado Warning	DMX	Tama	34 min
Jul 19, 8:35 PM CDT	Areal Flood Advisory	DMX	Black Hawk, Boone, Grundy, Jasper, Marshall, Polk and 3 more	3 hr
Jul 19, 8:48 PM CDT	Areal Flood Advisory	DMX	Audubon, Carroll, Dallas, Greene, Guthrie, Polk	116 min
Jul 19, 9:22 PM CDT	Severe Thunderstorm Warning	DMX	Polk, Warren	27 min
Jul 19, 9:48 PM CDT	Areal Flood Advisory	DMX	Jasper, Mahaska, Marion, Polk, Poweshiek, Warren	114 min
Jul 19, 10:07 PM CDT	Severe Thunderstorm Warning	DMX	Jasper, Marion, Polk, Warren	38 min
Jul 19, 10:29 PM CDT	Severe Thunderstorm Warning	DMX	Lucas, Marion, Monroe, Warren	30 min
Jul 19, 11:08 PM CDT	Severe Thunderstorm Warning	DMX	Wapello	28 min
Jul 20, 2:47 AM CDT	Severe Thunderstorm Warning	DMX	Boone, Polk, Story	28 min
Jul 20, 9:28 AM CDT	River Flood Warning	DMX	Mahaska	4 days

Nearby

Flash Flood Watches in Iowa, 2008 Every flash flood watch in 2008

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.