Alert archive / Colorado / Flash Flood Warnings in 2011

Flash Flood Warning 28, NWS Denver/Boulder, CO

July 17, 2011Boulder County, Colorado

NWS Denver/Boulder, CO issued this flash flood warning at Jul 17, 2011, 3:44 PM MDT for Boulder County, Colorado. It was in force for 3 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 17, 2011, 3:44 PM MDT (21:44 UTC)
Expired: Jul 17, 2011, 6:45 PM MDT
In force: 3 hr
Issued by: NWS Denver/Boulder, CO
Area: Storm-based polygon
Flood severity: None

County Boulder County, CO

The radar

The Denver radar (KFTG), 86 km from the middle of the area, began a volume at 21:48 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, 9.7 hours before the alert went out and 196 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 94 J/kg
Mixed-layer CIN: -352 J/kg
Mixed-layer LCL: 1885 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: 17 m²/s²
0-3 km storm-relative helicity: 22 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

940 
WGUS55 KBOU 172144
FFWBOU
COC013-180045-
/O.NEW.KBOU.FF.W.0028.110717T2144Z-110718T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE DENVER CO
344 PM MDT SUN JUL 17 2011

THE NATIONAL WEATHER SERVICE IN DENVER HAS ISSUED A

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

* UNTIL 645 PM MDT

* AT 343 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  VERY HEAVY RAIN FROM A THUNDERSTORM NEAR NEDERLAND...OR 33 MILES
  NORTHWEST OF DENVER. THIS STORM WAS MOVING NORTH AT 10 MPH.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO NEDERLAND
  AND ELDORA.

DOPPLER RADAR ESTIMATES THAT UP TO 2 INCHES OF RAIN HAS FALLEN FROM 
THIS STORM IN THE LAST 30 MINUTES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM THIS STORM WILL CAUSE FLASH FLOODING OF CREEKS
AND STREAMS...ROADS AND ROADSIDE CULVERTS. THE HEAVY RAINS COULD ALSO
TRIGGER ROCK SLIDES OR DEBRIS FLOWS IN STEEP TERRAIN.

IT IS IMPORTANT TO KNOW WHERE YOU ARE RELATIVE TO STREAMS...RIVERS...
OR CREEKS...WHICH CAN BECOME KILLERS IN HEAVY RAINS. CAMPERS SHOULD
AVOID CAMPING ALONG STREAMS OR CREEKS DURING THREATENING RAINS.

&&

LAT...LON 4002 10555 4002 10546 3994 10548 3993 10558

$$

2 follow-up statements

893 
WGUS75 KBOU 172208
FFSBOU

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
408 PM MDT SUN JUL 17 2011

COC013-180045-
/O.CON.KBOU.FF.W.0028.000000T0000Z-110718T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BOULDER CO-
408 PM MDT SUN JUL 17 2011

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 645 PM MDT FOR
SOUTHWESTERN BOULDER COUNTY...

AT 407 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED 
HEAVY RAIN HAD ENDED OVER SOUTHWESTERN BOULDER COUNTY.

LOCATIONS REMAINING IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
NEDERLAND AND ELDORA.

DOPPLER RADAR ESTIMATES THAT OVER 2 INCHES OF RAIN HAS FALLEN FROM 
PREVIOUS STORMS IN 30 MINUTES. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM THIS STORM WILL CAUSE FLASH FLOODING OF CREEKS
AND STREAMS...ROADS AND ROADSIDE CULVERTS. THE HEAVY RAINS COULD ALSO
TRIGGER ROCK SLIDES OR DEBRIS FLOWS IN STEEP TERRAIN.

IT IS IMPORTANT TO KNOW WHERE YOU ARE RELATIVE TO STREAMS...RIVERS...
OR CREEKS...WHICH CAN BECOME KILLERS IN HEAVY RAINS. CAMPERS SHOULD
AVOID CAMPING ALONG STREAMS OR CREEKS DURING THREATENING RAINS.

&&

LAT...LON 4002 10555 4002 10546 3994 10548 3993 10558

$$

442 
WGUS75 KBOU 180041
FFSBOU

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
641 PM MDT SUN JUL 17 2011

COC013-180052-
/O.EXP.KBOU.FF.W.0028.000000T0000Z-110718T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BOULDER CO-
641 PM MDT SUN JUL 17 2011

...THE FLASH FLOOD WARNING WILL EXPIRE AT 645 PM MDT FOR SOUTHWESTERN
BOULDER COUNTY...

FLOOD WATERS HAVE SUBSIDED AND FLASH FLOODING IS NO LONGER EXPECTED.

LAT...LON 4002 10555 4002 10546 3994 10548 3993 10558

$$

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 16, 6:33 PM MDT	River Flood Advisory	BOU	Morgan	40 hr
Jul 16, 6:33 PM MDT	River Flood Advisory	BOU	Logan, Morgan, Washington	63 hr
Jul 16, 9:37 PM MDT	Severe Thunderstorm Warning	BOU	Weld	35 min
Jul 17, 12:55 PM MDT	Areal Flood Advisory	BOU	Boulder, Grand, Larimer	80 min
Jul 17, 2:20 PM MDT	Special Weather Statement	BOU	Gilpin	25 min
Jul 17, 2:25 PM MDT	Severe Thunderstorm Warning	BOU	Gilpin	35 min
Jul 17, 2:29 PM MDT	Areal Flood Advisory	BOU	Clear Creek, Gilpin	91 min
Jul 17, 2:57 PM MDT	Flash Flood Warning	BOU	Clear Creek, Gilpin	3 hr
Jul 17, 3:33 PM MDT	Special Weather Statement	BOU	Boulder	27 min
Jul 17, 3:37 PM MDT	Areal Flood Advisory	BOU	Boulder	83 min
Jul 17, 3:59 PM MDT	Special Weather Statement	BOU	Boulder	31 min
Jul 17, 4:16 PM MDT	Areal Flood Advisory	BOU	Boulder	89 min
Jul 17, 4:31 PM MDT	Special Weather Statement	BOU	Boulder	29 min
Jul 17, 4:57 PM MDT	Special Weather Statement	BOU	Boulder	33 min
Jul 17, 5:01 PM MDT	Areal Flood Advisory	BOU	Boulder	89 min
Jul 17, 5:25 PM MDT	Special Weather Statement	BOU	Boulder	35 min

Nearby

Flash Flood Warnings in Colorado, 2011 Every 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.