Alert archive / Colorado / Flash Flood Warnings in 2021
Flash Flood Warning 47, NWS Denver/Boulder, CO
NWS Denver/Boulder, CO issued this flash flood warning at Jul 30, 2021, 2:51 PM MDT for Grand County, Colorado. It was in force for 4 hr. 1 report came from inside the area while it was in force.
The area
The outline as issued, with what was reported inside it.
The facts
- Issued
- Jul 30, 2021, 2:51 PM MDT (20:51 UTC)
- Expired
- Jul 30, 2021, 7:17 PM MDT
- In force
- 4 hr
- Issued by
- NWS Denver/Boulder, CO
- Area
- Storm-based polygon
- Flood severity
- None
County Grand County, CO
The radar
The Denver radar (KFTG), 136 km from the middle of the area, began a volume at 20:53 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.
What was reported inside it
| Time | Report | Where | Remark |
|---|---|---|---|
| Jul 30, 4:30 PM MDT | FLASH FLOOD | 10 Nne Hot Sulphur Spri, CO | SEVERAL MUD AND DEBRIS FLOWS ACROSS HIGHWAY 125. |
Local storm reports filed while the alert was in force, from inside its polygon or its counties.
The nearest sounding before it
Denver, CO (KDNR), launched 12:00Z, 8.9 hours before the alert went out and 241 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.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 2523 m above ground
- 0-6 km bulk shear
- 18 kt
- 0-1 km storm-relative helicity
- -18 m²/s²
- 0-3 km storm-relative helicity
- 2 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
295
WGUS55 KBOU 302051
FFWBOU
COC049-310000-
/O.NEW.KBOU.FF.W.0047.210730T2051Z-210731T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Denver CO
251 PM MDT Fri Jul 30 2021
The National Weather Service in Denver has issued a
* Flash Flood Warning for...
North Central Grand County in north central Colorado...
* Until 600 PM MDT.
* At 251 PM MDT, Doppler radar indicated thunderstorms producing
heavy rain across the warned area. Between 0.2 and 0.5 inches of
rain have fallen. Additional rainfall amounts of 0.5 to 1.5 inches
are possible in the warned area. Flash flooding is ongoing or
expected to begin shortly.
HAZARD...Flash flooding caused by thunderstorms.
SOURCE...Radar.
IMPACT...Flash flooding of small creeks and streams, gulches,
roads, and poor drainage and low-lying areas.
* Some locations that will experience flash flooding include...
mainly rural areas of North Central Grand County
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
Heavy Rainfall will cause flash flooding of small creeks, streams,
and ditches in the East Troublesome burn area. Some areas affected
include the Willow Creek valley along Highway 125 and Drowsy Water
Creek. Rock slides or debris flows can also be expected across rural
roads.
&&
LAT...LON 4033 10598 4029 10597 4025 10595 4012 10591
4010 10607 4021 10613 4028 10613 4034 10609
4036 10600
FLASH FLOOD...RADAR INDICATED
$$
Danielson4 follow-up statements
206
WGUS75 KBOU 302129
FFSBOU
Flash Flood Statement
National Weather Service Denver CO
329 PM MDT Fri Jul 30 2021
COC049-310000-
/O.CON.KBOU.FF.W.0047.000000T0000Z-210731T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Grand CO-
329 PM MDT Fri Jul 30 2021
...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 6 PM MDT THIS EVENING
FOR NORTH CENTRAL GRAND COUNTY...
At 329 PM MDT, Doppler radar indicated thunderstorms producing heavy
rain across the warned area. Between 1 and 1.7 inches of rain have
fallen. Additional rainfall amounts of 0.5 to 2 inches are possible
in the warned area. Flash flooding is ongoing or expected to begin
shortly.
HAZARD...Life threatening flash flooding. Thunderstorms producing
flash flooding.
SOURCE...Radar.
IMPACT...Life threatening flash flooding of creeks and streams,
roads, and low lying areas.
Some locations that will experience flash flooding include...
mainly rural areas of North Central Grand County
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
Heavy Rainfall will cause flash flooding of small creeks, streams,
and ditches in the East Troublesome burn area. Some areas affected
include the Willow Creek valley along Highway 125 and Drowsy Water
Creek. Rock slides or debris flows can also be expected across rural
roads.
&&
LAT...LON 4033 10598 4029 10597 4025 10595 4012 10591
4010 10607 4021 10613 4028 10613 4034 10609
4036 10600
FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
$$
Danielson966
WGUS75 KBOU 302253
FFSBOU
Flash Flood Statement
National Weather Service Denver CO
453 PM MDT Fri Jul 30 2021
COC049-310000-
/O.CON.KBOU.FF.W.0047.000000T0000Z-210731T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Grand CO-
453 PM MDT Fri Jul 30 2021
...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 6 PM MDT THIS EVENING
FOR NORTH CENTRAL GRAND COUNTY...
At 453 PM MDT, LAW ENFORCEMENT REPORTED MULTIPLE MUDSLIDES ON
HIGHWAY 125 IN THE EAST TROUBLESOME BURN SCAR. THUNDERSTORMS WITH
HEAVY RAIN HAVE MOVED SOUT OF THE WARNED AREA. HOWEVER, ADDITIONAL
HEAVY RAIN IS POSSIBLE IN THE NEXT HOUR.
HAZARD...Life threatening flash flooding. Thunderstorms producing
flash flooding.
SOURCE...Radar.
IMPACT...Life threatening flash flooding of creeks and streams,
roads, and low lying areas.
Some locations that will experience flash flooding include...
mainly rural areas of North Central Grand County
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
Move to higher ground now. Act quickly to protect your life.
Heavy Rainfall will cause flash flooding of small creeks, streams,
and ditches in the East Troublesome burn area. Some areas affected
include the North Inlet in the town of Grand Lake, the burned areas
on the west side of Rocky Mountain National Park, the Colorado River
above Shadow Mountain Reservoir, the Willow Creek valley along
Highway 125, Drowsy Water Creek, and the East Troublesome Creek
valley. Rock slides or debris flows can also be expected across
rural roads.
&&
LAT...LON 4033 10598 4029 10597 4025 10595 4012 10591
4010 10607 4021 10613 4028 10613 4034 10609
4036 10600
FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
$$
TH769
WGUS55 KBOU 302351
FFWBOU
COC049-310200-
/O.EXT.KBOU.FF.W.0047.000000T0000Z-210731T0200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Denver CO
551 PM MDT Fri Jul 30 2021
The National Weather Service in Denver has extended the
* Flash Flood Warning for...
North Central Grand County in north central Colorado...
* Until 800 PM MDT.
* At 551 PM MDT, Local law enforcement reported a mudslide closing
Highway 125 between Granby Dump Road and Forest Service Road 124.
HAZARD...Flash flooding caused by thunderstorms.
SOURCE...Law enforcement reported.
IMPACT...Flash flooding of small creeks and streams, gulches,
roads, and poor drainage and low-lying areas.
* Some locations that will experience flash flooding include...
mainly rural areas of North Central Grand County
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
Heavy Rainfall will cause flash flooding of small creeks, streams,
and ditches in the East Troublesome burn area. Some areas affected
include the Willow Creek valley along Highway 125. Rock slides or
debris flows can also be expected across rural roads.
&&
LAT...LON 4033 10598 4029 10597 4025 10595 4012 10591
4010 10607 4021 10613 4028 10613 4034 10609
4036 10600
FLASH FLOOD...OBSERVED
$$
Danielson311
WGUS75 KBOU 310117
FFSBOU
Flash Flood Statement
National Weather Service Denver CO
717 PM MDT Fri Jul 30 2021
COC049-310127-
/O.CAN.KBOU.FF.W.0047.000000T0000Z-210731T0200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Grand CO-
717 PM MDT Fri Jul 30 2021
...FLASH FLOOD WARNING IS CANCELLED FOR NORTH CENTRAL GRAND COUNTY...
Flood waters have receded. Flooding is no longer expected to pose a
threat. Please continue to heed remaining road closures.
A Flash Flood Watch remains in effect until 900 PM MDT Saturday for
Portions of central and north central Colorado.
LAT...LON 4033 10598 4029 10597 4025 10595 4012 10591
4010 10607 4021 10613 4028 10613 4034 10609
4036 10600
$$
DanielsonThe office that day
Everything else NWS Denver/Boulder, CO issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 29, 6:37 PM MDT | Areal Flood Advisory | BOU | Grand | 83 min |
| Jul 29, 7:27 PM MDT | Areal Flood Advisory | BOU | Grand | 93 min |
| Jul 29, 7:50 PM MDT | Flash Flood Warning | BOU | Jackson, Larimer | 3 hr |
| Jul 29, 8:14 PM MDT | Flash Flood Warning | BOU | Grand | 112 min |
| Jul 29, 9:32 PM MDT | Special Weather Statement | BOU | Jackson | 28 min |
| Jul 29, 10:19 PM MDT | Areal Flood Advisory | BOU | Larimer | 86 min |
| Jul 30, 1:01 PM MDT | Flash Flood Warning | BOU | Larimer | 7 hr |
| Jul 30, 1:08 PM MDT | Areal Flood Advisory | BOU | Larimer | 6 min |
| Jul 30, 1:14 PM MDT | Flash Flood Warning | BOU | Larimer | 3 hr |
| Jul 30, 1:34 PM MDT | Flash Flood Warning | BOU | Larimer | 6 hr |
| Jul 30, 2:07 PM MDT | Flash Flood Warning | BOU | Larimer | 5 hr |
| Jul 30, 2:30 PM MDT | Flash Flood Warning | BOU | Clear Creek, Grand | 3 hr |
| Jul 30, 2:48 PM MDT | Areal Flood Advisory | BOU | Larimer | 87 min |
| Jul 30, 3:02 PM MDT | Flash Flood Warning | BOU | Grand | 3 hr |
| Jul 30, 3:02 PM MDT | Special Weather Statement | BOU | Larimer | 43 min |
| Jul 30, 3:26 PM MDT | Severe Thunderstorm Warning | BOU | Larimer, Weld | 49 min |
| Jul 30, 3:45 PM MDT | Areal Flood Advisory | BOU | Grand | 2 hr |
| Jul 30, 3:59 PM MDT | Areal Flood Advisory | BOU | Larimer, Weld | 61 min |
| Jul 30, 4:11 PM MDT | Severe Thunderstorm Warning | BOU | Larimer, Weld | 49 min |
| Jul 30, 4:16 PM MDT | Flash Flood Warning | BOU | Grand | 3 hr |
| Jul 30, 4:28 PM MDT | Flash Flood Warning | BOU | Park | 3 hr |
| Jul 30, 4:30 PM MDT | Flash Flood Warning | BOU | Larimer | 4 hr |
| Jul 30, 5:36 PM MDT | Flash Flood Warning | BOU | Larimer | 3 hr |
| Jul 30, 5:37 PM MDT | Flash Flood Warning | BOU | Grand | 99 min |
Nearby
Flash Flood Warnings in Colorado, 2021Every flash flood warning in 2021
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.