Alert archive / Illinois / Flash Flood Watches in 2015

Flash Flood Watch 9, NWS Quad Cities, IA

September 18, 20155 counties in Iowa; 9 counties in Illinois

NWS Quad Cities, IA issued this flash flood watch at Sep 18, 2015, 3:51 AM CDT for 5 counties in Iowa; 9 counties in Illinois. It took effect at Sep 18, 2015, 1:00 PM CDT. It was in force for 10 hr.

The area

The counties it named.

The facts

Issued: Sep 18, 2015, 3:51 AM CDT (08:51 UTC)
In effect from: Sep 18, 2015, 1:00 PM CDT
Expired: Sep 18, 2015, 11:24 PM CDT
In force: 10 hr
Issued by: NWS Quad Cities, IA
Flood severity: None

Counties Cedar County, IA, Clinton County, IA, Jackson County, IA, Muscatine County, IA, Scott County, IA, Bureau County, IL, Carroll County, IL, Henry County, IL, Jo Daviess County, IL, Mercer County, IL, Putnam County, IL, Rock Island County, IL, Stephenson County, IL, Whiteside County, IL

The radar

The Quad Cities radar (KDVN), 28 km from the middle of the area, began a volume at 08:52 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, 8.9 hours before the alert went out and 21 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: 1343 J/kg
Mixed-layer CIN: -47 J/kg
Mixed-layer LCL: 1492 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 211 m²/s²
0-3 km storm-relative helicity: 495 m²/s²
Significant tornado parameter: 1.1
Supercell composite: 15.7

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 18, 3:28 AM CDT, 23 minutes earlier.

Area forecast discussion, Sep 18, 3:28 AM CDT, 23 minutes before

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Hazardous weather outlook, Sep 17, 5:00 AM CDT, 22 hours 51 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
500 AM CDT THU SEP 17 2015

IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007-
009-015>018-024>026-034-035-MOZ009-010-181000-
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-
500 AM CDT THU SEP 17 2015

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

SCATTERED STRONG AND POSSIBLY SEVERE STORMS ARE EXPECTED THIS
AFTERNOON AND EVENING ACROSS EASTERN IOWA INTO FAR NORTHWEST
ILLINOIS. THE STORM PREDICTION CENTER HAS PLACED A SLIGHT RISK OVER
THIS AREA. THE MAIN SEVERE WEATHER THREAT WILL BE LARGE HAIL AND
DAMAGING WIND.

WIDESPREAD THUNDERSTORMS ARE LIKELY OVERNIGHT ACROSS THE ENTIRE
OUTLOOK AREA AS A COLD FRONT MOVES THROUGH THE REGION. THE MAIN
STORM THREAT WILL BE LOCALLY HEAVY RAINFALL.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

ANOTHER ROUND OF THUNDERSTORMS ARE EXPECTED TO SPREAD ACROSS MUCH
OF THE OUTLOOK AREA FROM THE SOUTHWEST FRIDAY AFTERNOON AND NIGHT.
A FEW OF THESE STORMS MAY BE SEVERE WITH DAMAGING WINDS AND LARGE
HAIL THE PRIMARY THREATS. LATEST INDICATIONS SUGGEST AREAS MORE
FAVORABLE FOR STRONG TO SEVERE STORMS WILL BE ACROSS EAST CENTRAL
AND SOUTHEASTERN IOWA...FAR NORTHEASTERN MISSOURI...AND INTO WEST
CENTRAL ILLINOIS FRIDAY EVENING. THE STORM PREDICTION CENTER HAS
PLACED A SLIGHT RISK FOR SEVERE WEATHER FOR FRIDAY GENERALLY
ALONG AN WEST OF A LINE FROM CEDAR RAPIDS IOWA...TO THE QUAD
CITIES...AND TO MACOMB IN WEST CENTRAL ILLINOIS.

HEAVY RAINFALL WILL BE MORE OF A WIDESPREAD THREAT BY FRIDAY
NIGHT...WITH 1 TO 2 INCHES OF ADDITIONAL RAINFALL POSSIBLE IN
AREAS THAT GET REPEATED THUNDERSTORMS. HIGH RAINFALL RATES MAY
PRODUCE PONDING OF WATER ON ROADS AND TEMPORARY URBAN FLOODING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND EVENING.

SHEETS/12

In the hours before

Special weather statement, Sep 18, 12:29 AM CDT, 3 hours 22 minutes before

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Special weather statement, Sep 18, 1:18 AM CDT, 2 hours 33 minutes before

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Local storm report, Sep 18, 1:22 AM CDT, 2 hours 29 minutes before

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Special weather statement, Sep 18, 1:25 AM CDT, 2 hours 26 minutes before

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Local storm report, Sep 18, 2:41 AM CDT, 1 hour 10 minutes before

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Local storm report, Sep 18, 3:13 AM CDT, 38 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 17, 7:50 PM CDT	Severe Thunderstorm Warning	DVN	Clinton, Scott	25 min
Sep 17, 8:06 PM CDT	Severe Thunderstorm Warning	DVN	Jefferson, Van Buren	24 min
Sep 17, 8:50 PM CDT	Severe Thunderstorm Warning	DVN	Louisa, Muscatine, Washington	25 min
Sep 17, 9:14 PM CDT	Severe Thunderstorm Warning	DVN	Louisa, Muscatine	31 min
Sep 17, 9:47 PM CDT	Special Weather Statement	DVN	Scott	28 min
Sep 17, 11:55 PM CDT	Flash Flood Warning	DVN	Clinton, Jackson	6 hr
Sep 18, 12:25 AM CDT	Special Weather Statement	DVN	Jackson	65 min
Sep 18, 12:29 AM CDT	Special Weather Statement	DVN	Van Buren	61 min
Sep 18, 12:51 AM CDT	Severe Thunderstorm Warning	DVN	Van Buren	24 min
Sep 18, 1:18 AM CDT	Special Weather Statement	DVN	Lee	57 min
Sep 18, 1:25 AM CDT	Special Weather Statement	DVN	Scott	65 min
Sep 18, 3:39 PM CDT	Severe Thunderstorm Warning	DVN	Jefferson, Keokuk, Washington	41 min
Sep 18, 2:03 PM CDT	Special Weather Statement	DVN	Hancock, McDonough	42 min
Sep 18, 2:42 PM CDT	Special Weather Statement	DVN	McDonough	33 min
Sep 18, 2:59 PM CDT	Flash Flood Warning	DVN	Hancock, Henderson, McDonough, Warren	8 hr
Sep 18, 3:22 PM CDT	Special Weather Statement	DVN	Bureau, Putnam	53 min

Nearby

Flash Flood Watches in Illinois, 2015 Flash Flood Watches in Iowa, 2015 Every flash flood watch in 2015

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.