Alert archive / Iowa / Flash Flood Watches in 2008

Flash Flood Watch 16, NWS Quad Cities, IA

July 18, 200811 counties in Iowa

NWS Quad Cities, IA issued this flash flood watch at Jul 18, 2008, 3:00 AM CDT for 11 counties in Iowa. It took effect at Jul 18, 2008, 12:00 PM CDT. It was in force for 15 hr.

The area

The counties it named.

The facts

Issued: Jul 18, 2008, 3:00 AM CDT (08:00 UTC)
In effect from: Jul 18, 2008, 12:00 PM CDT
Expired: Jul 19, 2008, 3:02 AM CDT
In force: 15 hr
Issued by: NWS Quad Cities, IA
Flood severity: None

Counties Benton County, IA, Buchanan County, IA, Cedar County, IA, Delaware County, IA, Iowa County, IA, Jefferson County, IA, Johnson County, IA, Jones County, IA, Keokuk County, IA, Linn County, IA, Washington County, IA

The radar

The Quad Cities radar (KDVN), 95 km from the middle of the area, began a volume at 08:02 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.

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 Jul 18, 2:45 AM CDT, 15 minutes earlier.

Area forecast discussion, Jul 18, 2:45 AM CDT, 15 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
245 AM CDT FRI JUL 18 2008

.DISCUSSION...
NON LINEAR PROCESSES ARE AND WILL DOMINATE THE WEATHER REGIME
THROUGH MONDAY...AND POSSIBLY BEYOND.  AT THIS TIME...A NEARLY
STATIONARY FRONT IS THROUGH SOUTHEAST MN INTO NE...HOWEVER..A
OUTFLOW BOUNDARY IS NOW WELL ESTABLISHED TO ITS SOUTH DUE TO SEVERAL
DEEP CONVECTIVE CLUSTERS PERSISTING FROM LAST EVENING THROUGH EARLY
THIS MORNING.  THE EASTERN IOWA MCS HAS PRODUCED RAINFALL ON THE
ORDER OF 1 TO 3...AND POSSIBLY 4 INCHES OVER THE LAST 9 HOURS OR
SO.  THIS IS CAUSING RISES ON SOME RIVERS...INCLUDING THE IOWA RIVER
AT MARENGO...WHICH HAS RESULTED IN A FLOOD WARNING FOR THAT SITE.
WHILE FLASH FLOODING HAS NOT RESULTED OR BEEN REPORTED...WE ARE
CERTAINLY PRIMED FOR THIS THREAT AS NEW STORMS WITH HEAVY RAIN
POTENTIAL MOVE THROUGH OVER THE NEXT SEVERAL DAYS. THIS THREAT IS
OVER ALL AREAS...BUT OVER THE NEXT 24 HOURS WILL BE HIGHEST WHERE
LAST EVENINGS HEAVIEST TOTALS FELL. WE WILL ISSUE A FLASH FLOOD
WATCH FOR THIS AFTERNOON THROUGH SATURDAY MORNING TO COVER AFTERNOON
STORM REDEVELOPMENT AND ANOTHER POTENTIAL MCS EVENT TONIGHT FOR
AREAS WEST OF DELAWARE...CEDAR RAPIDS...TO SIGOURNEY.

CAPPING SHOULD BE LESS A FACTOR TODAY...AND MID LEVEL MOISTURE WILL
BE RATHER HIGH...THUS STORMS SHOULD BE MORE NUMEROUS...AND LESS
SEVERE THAN IOWA SAW YESTERDAY. AFTERNOON STORMS SHOULD FIRE ALONG
OUTFLOW BOUNDARIES WHICH ARE LIKELY GOING TO BE OVER THE CWA. THIS
COULD PRODUCE QUICK 1 TO 2 INCH RAINS LIKE YESTERDAY. COVERAGE MAY
EXPAND TOWARDS EVENING...OR DECREASE DEPENDING ON MESOSCALE NON
LINEAR PROCESSES. A SHORT WAVE APPROACHING FROM THE WEST AND
STRENGTHENING LLJ WILL LIKELY PRODUCE ANOTHER SIGNIFICANT MCS ACROSS
IOWA TONIGHT. THIS SHOULD BRING ANOTHER WIDESPREAD RAINFALL TO THE
REGION...MAINLY FROM 10 PM ONWARD INTO SATURDAY MORNING.

NO CHANGES HAVE BEEN MADE BEYOND SUNDAY MORNING IN THE
GRIDS...HOWEVER... THE EXTENDED LOOKS ACTIVE...WITH THE FINAL
DETAILS LOW IN CONFIDENCE AS THE NEXT 60 HOURS OR STORMS SHOULD
DETERMINE THE FRONTAL POSITION BEYOND SUNDAY.

TODAYS TEMPERATURES ARE A CHALLENGE...AND WE WILL UNDERCUT GUIDANCE
NORTHWEST SLIGHTLY...AND GO NEAR GUIDANCE SOUTHEAST. CLOUDS SHOULD
BE OPAQUE TO START THE DAY...BEFORE THINNING AND BECOMING OPAQUE
AGAIN AS MORE STORMS FIRE.
...ERVIN...

&&

.AVIATION...
06Z ANALYSIS HAS OUTFLOW BOUNDARY FROM EVENING CONVECTION ACROSS THE
AREA. WHERE PRECIP IS OCCURRING MID LEVEL CLOUDS ARE PRESENT WITH
SUB 3 KFT CLOUDS IN THE HEAVIEST PRECIP. TRENDS INDICATE TSRA THREAT
IS SLOWLY DIMINISHING WITH TIME. NEW MCS TO FIRE THIS EVENING AND
SHOULD AFFECT THE AREA LATE TONIGHT WITH KCID/KDBQ AT HIGHEST RISK
FOR TSRA. 3-5SM VSBYS IN HEAVIER RAIN AND SUB 3 KFT CIGS THIS
MORNING WITH KCID AT HIGHEST RISK. OVERALL...VFR CIGS/VSBYS EXPECTED
BY LATE MORNING/AFTERNOON WITH TSRA POSSIBLE ON OUTFLOW BOUNDARY.
...08...

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...FLASH FLOOD WATCH FROM 1 PM CDT THIS AFTERNOON THROUGH SATURDAY
     MORNING FOR BENTON-BUCHANAN-DELAWARE-IOWA-JEFFERSON-KEOKUK-
     LINN.

IL...NONE.
MO...NONE.
&&

ERVIN/08

Hazardous weather outlook, Jul 17, 4:40 AM CDT, 22 hours 20 minutes before

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In the hours before

Local storm report, Jul 17, 11:02 PM CDT, 3 hours 58 minutes before

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Local storm report, Jul 17, 11:32 PM CDT, 3 hours 28 minutes before

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Local storm report, Jul 17, 11:45 PM CDT, 3 hours 15 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
Jul 18, 2:12 AM CDT	River Flood Warning	DVN	Iowa, Johnson	12 days
Jul 18, 9:46 AM CDT	River Flood Warning	DVN	Johnson, Washington	5 days
Jul 18, 9:46 AM CDT	River Flood Warning	DVN	Keokuk	24 hr
Jul 18, 9:53 AM CDT	River Flood Warning	DVN	Johnson, Louisa, Washington	6 days
Jul 18, 9:53 AM CDT	River Flood Warning	DVN	Louisa	8 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; radar from the NEXRAD Level II archive.