Flash Flooding July 13 in Boulder and Fourmile Canyon

Last night, some of the worst fears came true for the Fourmile Canyon and Boulder.  I would argue that it could be worse, the storms they got could have been bigger, more stationary, and more pleantiful, but apparently what they got was enough to do some big damage.  This is particularly disturbing because this monsoon season isn't over yet and today could bring more problems for the area, depending on the placement of the storms.  Here's a collection of information I put together from the events.

Wednesday evening a very intense thunderstorm dropped large amounts of rain over the fourmile burn area.  Here's the text from the NWS's flash flood warning:

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 915 PM MDT FOR
CENTRAL BOULDER COUNTY...

AT 703 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED VERY
HEAVY RAIN FROM A THUNDERSTORM NEAR SUNSHINE...OR ABOUT 32 MILES
NORTHWEST OF DENVER. THIS STORM WAS MOVING NORTHEAST AT 15 MPH...
AND HEAVY RAIN WILL END BY 720 PM.

AUTOMATED RAIN GAUGES AND WEATHER SPOTTERS REPORTED BETWEEN FOUR
TENTHS AND 1.18 INCHES OF RAINFALL IN THE FOURMILE BURN AREA.  THE
HEAVIEST RAINFALL HAD OCCURRED OVER THE NORTHERN AND WESTERN
PORTIONS OF THE BURN AREA.

THE BOULDER COUNTY EMERGENCY MANAGER REPORTED DEBRIS FLOWS IN THE
FOURMILE BURN AREA.  IN ADDITION...FOURMILE CREEK WAS ALSO RISING.

LOCATIONS REMAINING IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
WALLSTREET...SUNSHINE...SUMMERVILLE...SALINA...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. IF YOU ENCOUNTER FLOOD WATERS...CLIMB TO
SAFETY.

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.

and an update to this

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.

This map of the Boulder Flood areas might be of interest. 

Here are some pictures from twitter, not from me, that show just a few glimpses of what was going on up there.

Gold Run Rd at mid-Salina after the flood 

Sunshine flooding: Car washed away CR 83 and Whispering Pines 

Sunshine canyon flooding 

Corner of Fourmile and Gold Run post flood 

 Our office of emergency management is always ontop of things and 

the Daily Camera has a nice summary of what happened.

While this was happening, sun was setting and I ran out to photograph a storm southeast of me from the top of Lehigh/Greenbriar, so this is all in the opposite direction as the canyons at risk.  I'll share more pics after I sort through them, but here's a highlight.  

Thunderstorm southeast of Boulder on July 13, 2011.  Photograph taken by me!

A little before this picture was taken, the sirens went off and I was warned that "You have a flash flood warning, the flooding of South Boulder Creek is imminent."  I was up on Shanahan Ridge as this was happening, so I wasn't too worried about this, but realized if anything big happened, I'd have a nice view of it.  In fact, looking back, I'm pretty sure the sirens were going off for people below our neighborhood, or they would have been much louder.  Nothing big happened, just a surge of water.  (See flood map above.)  Similarly, the same thing happened downtown in Boulder.  

I spend a lot of time telling my meteorology students to pay attention to the weather, turn on the radio for information, etc.  I was extremely impressed to find that during an emergency situation, I got sirens, a man explaining the situation over a loudspeaker, a text message from CU, and my weather radio going off (although I didn't have those last two pieces with me since I was outside).  What more could a meteorologist ask for?  Well done, Boulder!  

Here's a video of the sirens.  

And the loudspeaker man.  (Sorry, I'd love to have combined and edited my video, but my video editing software seems to have disappeared since the last time I wiped my computer)

My good friend Jason has taken a video of his bike trip down Boulder Creek just a few days ago to show you how high the water already is from a full week of monsoon rains.  It is well worth a look!

 Around 11:30 PM my weather radio started going off again.  This thing is LOUD.  I ran over to shut off the alarm and listen to the warning and it was indicating what is shown below.  That the Fourmile canyon was getting another thunderstorm and was having a flash flood warning.  Similarly to earlier, they sent out evacuation phone calls to tell people to get to higher ground.  A small surge went through the city while we were all sleeping, but no one was hurt through any of this (at least as far as I have heard).  There is plenty of cleanup to be done, though.  Let's hope they get a break today. 

This little guy in the green outline just west of Boulder prompted a second warning around 11:30pm.