Alert archive / Colorado / Flash Flood Warnings in 2021
Flash Flood Warning 66, NWS Denver/Boulder, CO
NWS Denver/Boulder, CO issued this flash flood warning at Aug 3, 2021, 4:05 PM MDT for Adams County, Arapahoe County, Colorado. It was in force for 115 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
- Aug 3, 2021, 4:05 PM MDT (22:05 UTC)
- Expired
- Aug 3, 2021, 6:00 PM MDT
- In force
- 115 min
- Issued by
- NWS Denver/Boulder, CO
- Area
- Storm-based polygon
- Flood severity
- None
Counties Adams County, CO, Arapahoe County, CO
The radar
The Denver radar (KFTG), 40 km from the middle of the area, began a volume at 22:07 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, 10.1 hours before the alert went out and 75 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
- 12 J/kg
- Mixed-layer CIN
- -226 J/kg
- Mixed-layer LCL
- 2110 m above ground
- 0-6 km bulk shear
- 13 kt
- 0-1 km storm-relative helicity
- -16 m²/s²
- 0-3 km storm-relative helicity
- -6 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
565
WGUS55 KBOU 032205
FFWBOU
COC001-005-040000-
/O.NEW.KBOU.FF.W.0066.210803T2205Z-210804T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Denver CO
405 PM MDT Tue Aug 3 2021
The National Weather Service in Denver has issued a
* Flash Flood Warning for...
Southeastern Adams County in northeastern Colorado...
Central Arapahoe County in northeastern Colorado...
* Until 600 PM MDT.
* At 405 PM MDT, Doppler radar indicated thunderstorms producing
heavy rain across the warned area. Between 1.5 and 2.5 inches of
rain have fallen. 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...
Byers.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Move to higher ground now. Act quickly to protect your life.
Be aware of your surroundings and do not drive on flooded roads.
Excessive runoff from this storm will cause flash flooding of small
creeks and streams, country roads, farmland along creeks, and other
low lying areas.
&&
LAT...LON 3985 10406 3984 10395 3974 10391 3973 10403
3970 10411 3959 10419 3965 10426 3973 10421
FLASH FLOOD...RADAR INDICATED
$$
MeierThe office that day
Everything else NWS Denver/Boulder, CO issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 2, 6:26 PM MDT | Flash Flood Warning | BOU | Larimer | 116 min |
| Aug 3, 3:41 AM MDT | Flash Flood Watch | BOU | Boulder, Clear Creek, Gilpin, Grand, Jackson, Jefferson and 3 more | 18 hr |
| Aug 3, 8:10 AM MDT | Areal Flood Advisory | BOU | Grand | 3 hr |
| Aug 3, 2:22 PM MDT | Areal Flood Advisory | BOU | Douglas, Jefferson | 113 min |
| Aug 3, 2:58 PM MDT | Flash Flood Warning | BOU | Elbert | 2 hr |
| Aug 3, 3:48 PM MDT | Areal Flood Advisory | BOU | Adams, Arapahoe, Elbert | 87 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.