Alert archive / Colorado / Flash Flood Watches in 2010

Flash Flood Watch 3, NWS Denver/Boulder, CO

July 31, 20104 counties in Colorado

NWS Denver/Boulder, CO issued this flash flood watch at Jul 31, 2010, 4:26 AM MDT for 4 counties in Colorado. It took effect at Jul 31, 2010, 6:00 AM MDT. It was in force for 15 hr.

The area

The counties it named.

The facts

Issued
Jul 31, 2010, 4:26 AM MDT (10:26 UTC)
In effect from
Jul 31, 2010, 6:00 AM MDT
Expired
Jul 31, 2010, 9:00 PM MDT
In force
15 hr
Issued by
NWS Denver/Boulder, CO
Flood severity
None

Counties Arapahoe County, CO, Douglas County, CO, Elbert County, CO, Lincoln County, CO

The radar

The Denver radar (KFTG), 59 km from the middle of the area, began a volume at 10:29 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

Grand Junction, CO (KGJT), launched 00:00Z, 10.4 hours before the alert went out and 368 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, Grand Junction, CO at 00:00Z on 2010-07-31Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 286 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, Grand Junction, CO at 00:00Z on 2010-07-31The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 1 square meters per square second.1939Sfc1 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
286 J/kg
Mixed-layer CIN
-35 J/kg
Mixed-layer LCL
2832 m above ground
0-6 km bulk shear
9 kt
0-1 km storm-relative helicity
1 m²/s²
0-3 km storm-relative helicity
9 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

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 Denver/Boulder, CO wrote its last area forecast discussion before this flash flood watch went out at Jul 31, 3:35 AM MDT, 51 minutes earlier.

Area forecast discussion, Jul 31, 3:35 AM MDT, 51 minutes before
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Hazardous weather outlook, Jul 30, 10:46 AM MDT, 17 hours 40 minutes before
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DENVER CO
1046 AM MDT FRI JUL 30 2010

COZ030>051-311200-
JACKSON COUNTY BELOW 9000 FEET-WEST JACKSON AND WEST GRAND
COUNTIES ABOVE 9000 FEET-GRAND AND SUMMIT COUNTIES BELOW 9000
FEET-SOUTH AND EAST JACKSON/LARIMER/NORTH AND NORTHEAST GRAND/
NORTHWEST BOULDER COUNTIES ABOVE 9000 FEET-SOUTH AND SOUTHEAST
GRAND/WEST CENTRAL AND SOUTHWEST BOULDER/GILPIN/CLEAR CREEK/
SUMMIT/NORTH AND WEST PARK COUNTIES ABOVE 9000 FEET-LARIMER AND
BOULDER COUNTIES BETWEEN 6000 AND 9000 FEET-JEFFERSON AND WEST
DOUGLAS COUNTIES ABOVE 6000 FEET/GILPIN/CLEAR CREEK/NORTHEAST PARK
COUNTIES BELOW 9000 FEET-CENTRAL AND SOUTHEAST PARK COUNTY-LARIMER
COUNTY BELOW 6000 FEET/NORTHWEST WELD COUNTY-BOULDER AND JEFFERSON
COUNTIES BELOW 6000 FEET/WEST BROOMFIELD COUNTY-NORTH DOUGLAS
COUNTY BELOW 6000 FEET/DENVER/WEST ADAMS AND ARAPAHOE COUNTIES/
EAST BROOMFIELD COUNTY-ELBERT/CENTRAL AND EAST DOUGLAS COUNTIES
ABOVE 6000 FEET-NORTHEAST WELD COUNTY-CENTRAL AND SOUTH WELD
COUNTY-MORGAN COUNTY-CENTRAL AND EAST ADAMS AND ARAPAHOE COUNTIES-
NORTH AND NORTHEAST ELBERT COUNTY BELOW 6000 FEET/NORTH LINCOLN
COUNTY-SOUTHEAST ELBERT COUNTY BELOW 6000 FEET/SOUTH LINCOLN
COUNTY-LOGAN COUNTY-WASHINGTON COUNTY-SEDGWICK COUNTY-PHILLIPS
COUNTY-
1046 AM MDT FRI JUL 30 2010

...FLASH FLOOD WATCH REMAINS IN EFFECT FOR THIS AFTERNOON AND
EVENING ACROSS THE PALMER DIVIDE...SOUTHERN FRONT RANGE FOOTHILLS
AND PARK COUNTY...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST AND NORTH CENTRAL
COLORADO.

.DAY ONE...TODAY AND TONIGHT

SCATTERED THUNDERSTORMS WILL AGAIN DEVELOP EARLY THIS AFTERNOON
ACROSS THE MOUNTAINS AND FRONT RANGE FOOTHILLS...THEN SPREAD OUT
ONTO THE ADJACENT PLAINS BY LATER THIS AFTERNOON. STORMS WILL BE
MORE NUMEROUS ALONG AND SOUTH OF THE INTERSTATE 70 CORRIDOR WHERE
MOISTURE LEVELS ARE HIGHER.  DRIER AND A BIT MORE STABLE AIRMASS IS
MOVING IN FROM NORTHWEST COLORADO...SO LOCATIONS NORTH OF INTERSTATE
70 AND STRETCHING OUT INTO THE FAR NORTHEAST PLAINS WILL SEE LESS
THUNDERSTORM ACTIVITY.

AS IN PREVIOUS DAYS...THE MAIN THREAT WITH THE STORMS WILL BE HEAVY
RAIN AND POSSIBLE FLASH FLOODING WITH THE WEAK FLOW ALOFT IN THE
ATMOSPHERE. PARK...SOUTHERN JEFFERSON...AND DOUGLAS COUNTIES WILL
SEE THE HIGHEST THREAT OF FLASH FLOODING.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THERE WILL BE A CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS EACH
DAY THIS WEEKEND...A BIT MORE NUMEROUS ACROSS THE MOUNTAINS AND
HIGHER TERRAIN. THE MAIN THREAT WITH THESE STORMS WILL BE HEAVY
RAIN.  THE CHANCE WILL INCREASE FOR THE PLAINS MONDAY AS A COOL
FRONT MOVES SOUTH INTO NORTHERN COLORADO. TEMPERATURES WILL BE
SLIGHTLY ABOVE SEASONABLE NORMALS FOR THE WEEKEND THEN DROP TO NEAR
NORMAL MONDAY THROUGH THURSDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY OR TONIGHT...HOWEVER
HEAVY RAINFALL AND FLOODING REPORTS WILL BE APPRECIATED.

ENTREKIN/KRIEDERMAN

The office that day

Everything else NWS Denver/Boulder, CO issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 30, 6:33 PM MDTAreal Flood AdvisoryBOUArapahoe, Denver, Douglas79 min
Jul 30, 7:06 PM MDTAreal Flood AdvisoryBOUDouglas84 min
Jul 30, 7:55 PM MDTAreal Flood AdvisoryBOUDouglas95 min
Jul 31, 12:20 AM MDTAreal Flood AdvisoryBOULincoln85 min
Jul 31, 2:30 PM MDTAreal Flood AdvisoryBOUWashington90 min

Nearby

Flash Flood Watches in Colorado, 2010Every flash flood watch in 2010

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.