Alert archive / Illinois / Flash Flood Watches in 2011

Flash Flood Watch 4, NWS Chicago, IL

July 27, 201110 counties in Illinois; Lake County, Porter County, Indiana

NWS Chicago, IL issued this flash flood watch at Jul 27, 2011, 11:44 AM CDT for 10 counties in Illinois; Lake County, Porter County, Indiana. It took effect at Jul 27, 2011, 4:00 PM CDT. It was in force for 39 hr.

The area

The counties it named.

The facts

Issued: Jul 27, 2011, 11:44 AM CDT (16:44 UTC)
In effect from: Jul 27, 2011, 4:00 PM CDT
Expired: Jul 29, 2011, 7:00 AM CDT
In force: 39 hr
Issued by: NWS Chicago, IL
Flood severity: None

Counties Boone County, IL, DeKalb County, IL, DuPage County, IL, Kane County, IL, Kendall County, IL, Lake County, IL, Lee County, IL, McHenry County, IL, Ogle County, IL, Winnebago County, IL, Lake County, IN, Porter County, IN

The radar

The Chicago radar (KLOT), 47 km from the middle of the area, began a volume at 16:47 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 12:00Z, 4.7 hours before the alert went out and 176 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: 2106 J/kg
Mixed-layer CIN: -122 J/kg
Mixed-layer LCL: 792 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 151 m²/s²
0-3 km storm-relative helicity: 193 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 8.5

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 Chicago, IL wrote its last area forecast discussion before this flash flood watch went out at Jul 27, 11:05 AM CDT, 39 minutes earlier.

Area forecast discussion, Jul 27, 11:05 AM CDT, 39 minutes before

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Hazardous weather outlook, Jul 27, 11:37 AM CDT, 7 minutes before

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In the hours before

Local storm report, Jul 27, 10:30 AM CDT, 1 hour 14 minutes before

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Local storm report, Jul 27, 10:39 AM CDT, 1 hour 5 minutes before

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Local storm report, Jul 27, 10:40 AM CDT, 1 hour 4 minutes before

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Local storm report, Jul 27, 10:45 AM CDT, 59 minutes before

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Local storm report, Jul 27, 11:01 AM CDT, 43 minutes before

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Local storm report, Jul 27, 11:27 AM CDT, 17 minutes before

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The office that day

Everything else NWS Chicago, IL issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 27, 8:43 AM CDT	Special Weather Statement	LOT	Boone, Cook, DeKalb, DuPage, Kane, Lake and 1 more	62 min
Jul 27, 9:35 AM CDT	Areal Flood Advisory	LOT	Lake, McHenry	4 hr
Jul 27, 9:40 AM CDT	Special Weather Statement	LOT	Cook, Kane, Lake	50 min
Jul 27, 10:16 AM CDT	Flash Flood Warning	LOT	Lake	4 hr
Jul 27, 12:12 PM CDT	Heat Advisory	LOT	Ford, Grundy, Iroquois, Kankakee, LaSalle, Livingston	7 hr
Jul 27, 1:54 PM CDT	Areal Flood Advisory	LOT	Lake	91 min
Jul 27, 3:22 PM CDT	Areal Flood Warning	LOT	Lake	19 hr

Nearby

Flash Flood Watches in Illinois, 2011 Flash Flood Watches in Indiana, 2011 Every flash flood watch in 2011

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.