Alert archive / Colorado / Flash Flood Warnings in 2011

Flash Flood Warning 32, NWS Denver/Boulder, CO

July 19, 2011Boulder County, Colorado

NWS Denver/Boulder, CO issued this flash flood warning at Jul 19, 2011, 3:27 PM MDT for Boulder County, Colorado. It was in force for 2 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Jul 19, 2011, 3:27 PM MDT (21:27 UTC)
Expired
Jul 19, 2011, 5:30 PM MDT
In force
2 hr
Issued by
NWS Denver/Boulder, CO
Area
Storm-based polygon
Flood severity
None

County Boulder County, CO

The radar

The Denver radar (KFTG), 78 km from the middle of the area, began a volume at 21:29 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

Denver, CO (KDNR), launched 12:00Z, 9.5 hours before the alert went out and 185 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, Denver, CO at 12:00Z on 2011-07-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 928 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, Denver, CO at 12:00Z on 2011-07-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -4 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
928 J/kg
Mixed-layer CIN
-229 J/kg
Mixed-layer LCL
1803 m above ground
0-6 km bulk shear
23 kt
0-1 km storm-relative helicity
-4 m²/s²
0-3 km storm-relative helicity
6 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.9

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

202 
WGUS55 KBOU 192127
FFWBOU
COC013-192330-
/O.NEW.KBOU.FF.W.0032.110719T2127Z-110719T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE DENVER CO
327 PM MDT TUE JUL 19 2011

THE NATIONAL WEATHER SERVICE IN DENVER HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  CENTRAL BOULDER COUNTY IN NORTHEAST COLORADO

* UNTIL 530 PM MDT

* AT 327 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  VERY HEAVY RAIN FROM A THUNDERSTORM 7 MILES SOUTH OF WALLSTREET...
  OR 28 MILES NORTHWEST OF DENVER. THIS STORM WAS MOVING NORTH AT 20
  MPH.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
  WALLSTREET...SUNSHINE...SUMMERVILLE...SALINA...CRISMAN AND GOLD
  HILL.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLASH FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR OCCURRING.
IF YOU ARE IN THE WARNING AREA MOVE TO HIGHER GROUND IMMEDIATELY.
RESIDENTS LIVING ALONG STREAMS AND CREEKS SHOULD TAKE IMMEDIATE
PRECAUTIONS TO PROTECT LIFE AND PROPERTY. DO NOT ATTEMPT TO CROSS
SWIFTLY FLOWING WATERS OR WATERS OF UNKNOWN DEPTH BY FOOT OR BY
AUTOMOBILE. TURN AROUND...DO NOT DROWN.

THIS IS A LIFE THREATENING SITUATION. HEAVY RAINFALL WILL CAUSE
EXTENSIVE AND SEVERE FLASH FLOODING OF CREEKS...STREAMS...AND DITCHES
IN THE FOURMILE BURN AREA. SOME DRAINAGE BASINS IMPACTED INCLUDE
FOURMILE CREEK...GOLD RUN...AND FOURMILE CANYON CREEK. SEVERE DEBRIS
FLOWS CAN ALSO BE ANTICIPATED ACROSS ROADS. ROADS AND DRIVEWAYS MAY
BE WASHED AWAY IN PLACES. IF YOU ENCOUNTER FLOOD WATERS...CLIMB TO
SAFETY.

&&

LAT...LON 4006 10544 4008 10540 4009 10537 4008 10533
      4004 10533 4001 10538 4004 10544

$$



RJK
2 follow-up statements
959 
WGUS75 KBOU 192223
FFSBOU

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
423 PM MDT TUE JUL 19 2011

COC013-192330-
/O.CON.KBOU.FF.W.0032.000000T0000Z-110719T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BOULDER CO-
423 PM MDT TUE JUL 19 2011

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 530 PM MDT FOR THE 
FOURMILE BURN AREA IN CENTRAL BOULDER COUNTY...

AT 410 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED 
HEAVY RAIN FROM A THUNDERSTORM 3 MILES SOUTH OF WALLSTREET...OR 
ABOUT 30 MILES NORTHWEST OF DENVER. THIS STORM WAS MOVING NORTH AT 
20 MPH. 

AUTOMATED RAIN GAUGES INDICATE THAT UP TO 0.2 INCH OF RAIN HAS 
FALLEN IN THE FOURMILE BURN AREA. 0.5 TO 1 INCH FELL WITH THE SAME 
STORM FARTHER SOUTH IN BOULDER COUNTY.

THE POTENTIAL REMAINS FOR MORE STORMS TO MOVE FROM THE SOUTH INTO 
BOULDER COUNTY WITHIN THE NEXT HOUR.  

LOCATIONS REMAINING IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
WALLSTREET...SUNSHINE...SUMMERVILLE...SALINA...CRISMAN AND GOLD HILL.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

MOST FLASH FLOOD DEATHS OCCUR IN AUTOMOBILES. DO NOT ATTEMPT TO CROSS
BRIDGES...DIPS...OR OTHER LOW SPOTS IF WATER COVERS THE ROADWAY.
NEVER TRY TO CROSS A FLOWING STREAM...EVEN A SMALL ONE...ON FOOT. TO
ESCAPE RISING WATER CLIMB TO HIGHER GROUND.

&&

LAT...LON 4006 10544 4008 10540 4009 10537 4008 10533
      4004 10533 4001 10538 4004 10544

$$
163 
WGUS75 KBOU 192330
FFSBOU

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
530 PM MDT TUE JUL 19 2011

COC013-192345-
/O.EXP.KBOU.FF.W.0032.000000T0000Z-110719T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BOULDER CO-
530 PM MDT TUE JUL 19 2011

...THE FLASH FLOOD WARNING WILL EXPIRE AT 530 PM MDT FOR THE 
FOURMILE BURN AREA IN CENTRAL BOULDER COUNTY...

THE HEAVY RAINFALL OVER THE FOURMILE BURN AREA ENDED NEARLY AN HOUR 
AGO. THEREFORE THE FLASH FLOOD WARNING IS BEING ALLOWED TO EXPIRE.

LAT...LON 4006 10544 4008 10540 4009 10537 4008 10533
      4004 10533 4001 10538 4004 10544

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 18, 6:08 PM MDTFlash Flood WarningBOULarimer2 hr
Jul 18, 6:57 PM MDTAreal Flood AdvisoryBOUSummit93 min
Jul 18, 7:25 PM MDTFlash Flood WarningBOUSummit95 min
Jul 18, 7:29 PM MDTAreal Flood AdvisoryBOUSummit91 min
Jul 18, 8:30 PM MDTAreal Flood AdvisoryBOUPark2 hr
Jul 18, 8:52 PM MDTFlash Flood WarningBOUSummit113 min
Jul 18, 9:28 PM MDTAreal Flood AdvisoryBOUGrand24 hr
Jul 18, 10:52 PM MDTAreal Flood AdvisoryBOUSummit20 hr
Jul 19, 11:13 AM MDTFlash Flood WatchBOUBoulder, Clear Creek, Gilpin, Grand, Jackson, Jefferson and 3 more9 hr
Jul 19, 2:53 PM MDTSpecial Weather StatementBOUGilpin37 min
Jul 19, 4:19 PM MDTSpecial Weather StatementBOUBroomfield26 min
Jul 19, 4:21 PM MDTAreal Flood AdvisoryBOUClear Creek, Gilpin, Jefferson, Park95 min
Jul 19, 4:58 PM MDTSpecial Weather StatementBOUBroomfield32 min
Jul 19, 5:09 PM MDTSpecial Weather StatementBOULarimer36 min
Jul 19, 5:11 PM MDTSevere Thunderstorm WarningBOUAdams, Weld49 min
Jul 19, 5:37 PM MDTSpecial Weather StatementBOUDenver23 min
Jul 19, 5:59 PM MDTSpecial Weather StatementBOUDenver31 min

Nearby

Flash Flood Warnings in Colorado, 2011Every flash flood warning 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.