Alert archive / Colorado / Flash Flood Warnings in 2011

Flash Flood Warning 20, NWS Denver/Boulder, CO

July 13, 2011Boulder County, Colorado

NWS Denver/Boulder, CO issued this flash flood warning at Jul 13, 2011, 8:08 PM MDT for Boulder County, Colorado. It was in force for 103 min. 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 13, 2011, 8:08 PM MDT (02:08 UTC)
Expired
Jul 13, 2011, 9:51 PM MDT
In force
103 min
Issued by
NWS Denver/Boulder, CO
Area
Storm-based polygon
Flood severity
None

County Boulder County, CO

The radar

The Denver radar (KFTG), 73 km from the middle of the area, began a volume at 02:09 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 00:00Z, 2.1 hours before the alert went out and 180 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 00:00Z on 2011-07-14Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 856 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Denver, CO at 00:00Z on 2011-07-14The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -31 square meters per square second.193958Sfc1 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
856 J/kg
Mixed-layer CIN
-22 J/kg
Mixed-layer LCL
2153 m above ground
0-6 km bulk shear
28 kt
0-1 km storm-relative helicity
-31 m²/s²
0-3 km storm-relative helicity
110 m²/s²
Significant tornado parameter
0.0
Supercell composite
2.0

Open this sounding in Storm Lab

The text

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

013 
WGUS55 KBOU 140208
FFWBOU
COC013-140500-
/O.NEW.KBOU.FF.W.0020.110714T0208Z-110714T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE DENVER CO
808 PM MDT WED JUL 13 2011

THE NATIONAL WEATHER SERVICE IN DENVER HAS ISSUED A

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

* UNTIL 1100 PM MDT

* AT 806 PM MDT...FLASH FLOODING WAS OBSERVED ALONG FOURMILE CREEK.  
  THE CREST OF THE FLOOD WATERS WAS REACHING BOULDER CREEK...WITH
  A RAPID SURGE AND INCREASE OF AT LEAST 4 FEET OF WATER.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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. 

THIS WARNING ALSO INCLUDES BOULDER CREEK FROM FOURMILE CREEK 
DOWNSTREAM TO THE CANYON MOUTH WEST OF BOULDER.

IF YOU ENCOUNTER FLOOD WATERS...CLIMB TO SAFETY.

&&

LAT...LON 4009 10536 4008 10530 4007 10527 4004 10527
      4000 10525 4000 10532 4002 10540 4005 10544

$$
BARJENBRUCH
2 follow-up statements
360 
WGUS75 KBOU 140259
FFSBOU

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
859 PM MDT WED JUL 13 2011

COC013-140500-
/O.CON.KBOU.FF.W.0020.000000T0000Z-110714T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BOULDER CO-
859 PM MDT WED JUL 13 2011

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1100 PM MDT FOR
CENTRAL BOULDER COUNTY...

SIGNIFICANT FLASH FLOODING WAS OBSERVED EARLIER THIS EVENING IN THE 
FOURMILE BURN AREA AND ALONG FOURMILE CREEK DOWN TO BOULDER CREEK. 
 
THE CREST OF THE FLOOD WATERS WAS NOW MOVING EASTWARD THROUGH THE 
CITY OF BOULDER...WITH A SLOW DECREASE IN FLOWS EXPECTED THROUGH THE 
COURSE OF THE EVENING.  WHILE NO SIGNIFICANT FLASH FLOODING WAS 
OBSERVED IN BOULDER...SOME TRAILS AND BIKE PATHS ALONG BOULDER CREEK 
MAY BE FLOODED IN TOWN.

THERE WERE REPORTS FROM EARLIER THIS EVENING OF 3 TO 4 FEET OF WATER 
RUNNING OVER THE ROAD NEAR THE JUNCTION OF FOURMILE CANYON ROAD AND 
GOLD RUN ROAD.  SOME HOMES HAD WATER UP TO THE WINDOWS AT THAT 
LOCATION AS WELL.  THOSE FLOOD WATERS HAVE SUBSIDED.  HOWEVER...MANY 
ROADS AND DRIVEWAYS MAY BE WASHED OUT.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS IS A LIFE THREATENING SITUATION. HEAVY RAINFALL HAS CAUSED
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 HAVE 
BEEN WASHED AWAY IN PLACES...AND TRAVEL MAY BE IMPOSSIBLE IN THE 
FOURMILE BURN AREA.

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE 
ROADWAY AS THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO 
CROSS SAFELY. DO NOT UNDERESTIMATE THE POWER OF FLOOD WATERS. ONLY A 
FEW INCHES OF RAPIDLY FLOWING WATER CAN QUICKLY CARRY AWAY YOUR 
VEHICLE. TURN AROUND...DO NOT DROWN.

&&

LAT...LON 4009 10536 4008 10530 4007 10527 4004 10527
      4000 10525 4000 10532 4002 10540 4005 10544

$$
BARJENBRUCH
194 
WGUS75 KBOU 140351
FFSBOU

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
951 PM MDT WED JUL 13 2011

COC013-140357-
/O.CAN.KBOU.FF.W.0020.000000T0000Z-110714T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BOULDER CO-
951 PM MDT WED JUL 13 2011

...THE FLASH FLOOD WARNING HAS BEEN CANCELLED FOR CENTRAL BOULDER
COUNTY...

ALL STREAMS INCLUDING FOURMILE CREEK AND BOULDER CREEK WERE RECEDING 
QUICKLY AND RETURNING TO NORMAL FLOWS.

BOULDER COUNTY EMERGENCY MANAGEMENT REPORTED NUMEROUS ROADS AND 
DRIVEWAYS IN THE FOURMILE BURN AREA AND ALONG FOURMILE CREEK WERE 
WASHED OUT EARLIER THIS EVENING.  NUMEROUS DEBRIS FLOWS HAVE ALSO 
OCCURRED.  TRAVEL MAY BE IMPOSSIBLE IN THE BURN AREA AND IS NOT 
RECOMMENDED.

THERE IS STILL A CHANCE OF THUNDERSTORMS INTO THE EARLY MORNING 
HOURS...SO RESIDENTS AND EMERGENCY OFFICIALS ARE URGED TO REMAIN 
ALERT FOR RAPIDLY CHANGING WEATHER CONDITIONS.

LAT...LON 4009 10536 4008 10530 4007 10527 4004 10527
      4000 10525 4000 10532 4002 10540 4005 10544

$$
BARJENBRUCH

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 13, 6:17 PM MDTFlash Flood WarningBOUBoulder3 hr
Jul 13, 6:32 PM MDTAreal Flood AdvisoryBOUAdams, Arapahoe, Denver, Jefferson43 min
Jul 13, 6:40 PM MDTSevere Thunderstorm WarningBOUAdams, Arapahoe, Denver, Jefferson19 min
Jul 13, 6:54 PM MDTAreal Flood AdvisoryBOUGrand22 hr
Jul 13, 7:13 PM MDTSevere Thunderstorm WarningBOUBoulder, Larimer34 min
Jul 13, 7:34 PM MDTSevere Thunderstorm WarningBOULarimer26 min
Jul 13, 7:59 PM MDTSevere Thunderstorm WarningBOULarimer, Weld28 min
Jul 13, 8:37 PM MDTAreal Flood AdvisoryBOUBoulder75 min
Jul 13, 9:01 PM MDTSevere Thunderstorm WarningBOUDouglas, Jefferson44 min
Jul 13, 9:05 PM MDTSevere Thunderstorm WarningBOUAdams, Arapahoe, Denver55 min
Jul 13, 9:28 PM MDTAreal Flood AdvisoryBOUAdams, Arapahoe, Broomfield, Denver, Douglas, Jefferson77 min
Jul 13, 9:55 PM MDTSevere Thunderstorm WarningBOUAdams, Weld33 min
Jul 13, 10:58 PM MDTAreal Flood AdvisoryBOUArapahoe, Douglas92 min
Jul 13, 11:15 PM MDTFlash Flood WarningBOUBoulder3 hr
Jul 13, 11:16 PM MDTFlash Flood WarningBOUBoulder3 hr
Jul 13, 11:48 PM MDTAreal Flood AdvisoryBOUAdams, Morgan, Washington87 min
Jul 14, 12:35 AM MDTAreal Flood AdvisoryBOUAdams, Arapahoe, Morgan, Washington81 min
Jul 14, 5:25 AM MDTFlash Flood WatchBOUAdams, Arapahoe, Boulder, Broomfield, Clear Creek, Denver and 10 more16 hr
Jul 14, 11:03 AM MDTAreal Flood AdvisoryBOUMorgan, Weld71 hr
Jul 14, 1:00 PM MDTFlash Flood WarningBOUBoulder3 hr
Jul 14, 1:10 PM MDTSpecial Weather StatementBOUJefferson35 min
Jul 14, 1:48 PM MDTAreal Flood AdvisoryBOUDouglas87 min
Jul 14, 1:57 PM MDTSevere Thunderstorm WarningBOUDouglas, Elbert48 min
Jul 14, 2:09 PM MDTFlash Flood WarningBOUBoulder2 hr
Jul 14, 2:40 PM MDTSevere Thunderstorm WarningBOUArapahoe, Denver, Douglas50 min
Jul 14, 3:02 PM MDTAreal Flood AdvisoryBOUArapahoe, Denver26 min
Jul 14, 3:22 PM MDTFlash Flood WarningBOUArapahoe, Denver, Jefferson2 hr
Jul 14, 3:28 PM MDTSevere Thunderstorm WarningBOUAdams, Arapahoe, Denver47 min
Jul 14, 4:00 PM MDTSevere Thunderstorm WarningBOUAdams, Arapahoe22 min
Jul 14, 4:16 PM MDTAreal Flood AdvisoryBOUArapahoe, Elbert89 min
Jul 14, 4:31 PM MDTAreal Flood AdvisoryBOUGrand71 hr
Jul 14, 5:10 PM MDTAreal Flood AdvisoryBOUBoulder55 min
Jul 14, 5:21 PM MDTSpecial Weather StatementBOUAdams24 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.