Alert archive / Colorado / Flash Flood Watches in 2021
Flash Flood Watch 8, NWS Denver/Boulder, CO
NWS Denver/Boulder, CO issued this flash flood watch at Aug 1, 2021, 2:04 PM MDT for 9 counties in Colorado. It took effect at Aug 2, 2021, 12:00 PM MDT. It was in force for 10 hr.
The area
The counties it named.
The facts
- Issued
- Aug 1, 2021, 2:04 PM MDT (20:04 UTC)
- In effect from
- Aug 2, 2021, 12:00 PM MDT
- Expired
- Aug 2, 2021, 10:00 PM MDT
- In force
- 10 hr
- Issued by
- NWS Denver/Boulder, CO
- Flood severity
- None
Counties Boulder County, CO, Clear Creek County, CO, Gilpin County, CO, Grand County, CO, Jackson County, CO, Jefferson County, CO, Larimer County, CO, Park County, CO, Summit County, CO
The radar
The Denver radar (KFTG), 102 km from the middle of the area, began a volume at 20:03 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, 8.1 hours before the alert went out and 213 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
- 5 J/kg
- Mixed-layer CIN
- -51 J/kg
- Mixed-layer LCL
- 1076 m above ground
- 0-6 km bulk shear
- 4 kt
- 0-1 km storm-relative helicity
- -14 m²/s²
- 0-3 km storm-relative helicity
- 3 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
312 WGUS65 KBOU 012004 FFABOU URGENT - IMMEDIATE BROADCAST REQUESTED Flood Watch National Weather Service Denver CO 204 PM MDT Sun Aug 1 2021 COZ032>034-020415- /O.NEW.KBOU.FF.A.0008.210802T1800Z-210803T0400Z/ /00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/ Grand and Summit Counties Below 9000 Feet-South and East Jackson/Larimer/North and Northeast Grand/Northwest Boulder Counties Above 9000 Feet-South and Southeast Grand/West Central and Southwest Boulder/Gilpin/Clear Creek/Summit/North and West Park Counties Above 9000 Feet- Including the cities of Kenosha Mountains, Hot Sulphur Springs, Kremmling, Indian Peaks, Dillon, Eisenhower Tunnel, Fraser, East Slopes Southern Gore Range, Mount Evans, Laramie and Medicine Bow Mountains, Grand Lake, Cameron Pass, Granby, Breckenridge, Winter Park, Rocky Mountain National Park, Willow Creek Pass, Rabbit Ears Range, East Slopes Mosquito Range, Williams Fork Mountains, and Berthoud Pass 204 PM MDT Sun Aug 1 2021 ...FLASH FLOOD WATCH IN EFFECT FROM MONDAY AFTERNOON THROUGH MONDAY EVENING... The National Weather Service in Denver has issued a * Flash Flood Watch for Portions of central and north central Colorado, including the following areas, in central Colorado, Grand and Summit Counties Below 9000 Feet and South and Southeast Grand/West Central and Southwest Boulder/Gilpin/Clear Creek/Summit/North and West Park Counties Above 9000 Feet. In north central Colorado, South and East Jackson/Larimer/North and Northeast Grand/Northwest Boulder Counties Above 9000 Feet. * From Monday afternoon through Monday evening. * Thunderstorms with locally heavy rainfall are expected to develop across the mountains Monday afternoon, and continue into the evening. Stronger storms will be capable of producing up to 1 inch of rain in 40 minutes. Burn areas west of the Continental Divide like East Troublesome and Williams Fork will be most prone to flash flooding, although there may be a risk of flooding in portions of the Cameron Peak burn area by late in the day. * Burn scars will be especially susceptible to heavy rainfall, leading to quick runoff and debris and mud flows. PRECAUTIONARY/PREPAREDNESS ACTIONS... You should monitor later forecasts and be prepared to take action should Flash Flood Warnings be issued. && $$ Barjenbruch
2 follow-up statements
960 WGUS65 KBOU 020803 FFABOU URGENT - IMMEDIATE BROADCAST REQUESTED Flood Watch National Weather Service Denver CO 203 AM MDT Mon Aug 2 2021 COZ035-037-030400- /O.EXA.KBOU.FF.A.0008.210802T1800Z-210803T0400Z/ /00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/ Larimer and Boulder Counties Between 6000 and 9000 Feet-Central and Southeast Park County- Including the cities of Glendevey, Hartsel, Nederland, Fairplay, Red Feather Lakes, Estes Park, Lake George, and South Park 203 AM MDT Mon Aug 2 2021 ...FLASH FLOOD WATCH IN EFFECT FROM NOON MDT TODAY THROUGH THIS EVENING... The National Weather Service in Denver has expanded the * Flash Flood Watch to include Portions of central and north central Colorado, including the following areas, in central Colorado, Central and Southeast Park County. In north central Colorado, Larimer and Boulder Counties Between 6000 and 9000 Feet. * From Noon MDT today through this evening. * Thunderstorms with locally heavy rainfall are expected to develop across the mountains this afternoon, and continue into the evening. Stronger storms will be capable of producing up to 1 inch of rain in 40 minutes. * The Cameron Peak and Weston Pass burn scars will be especially susceptible to heavy rainfall, leading to quick runoff and debris and mud flows. PRECAUTIONARY/PREPAREDNESS ACTIONS... You should monitor later forecasts and be prepared to take action should Flash Flood Warnings be issued. && $$ COZ032>034-030400- /O.CON.KBOU.FF.A.0008.210802T1800Z-210803T0400Z/ /00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/ Grand and Summit Counties Below 9000 Feet-South and East Jackson/Larimer/North and Northeast Grand/Northwest Boulder Counties Above 9000 Feet-South and Southeast Grand/West Central and Southwest Boulder/Gilpin/Clear Creek/Summit/North and West Park Counties Above 9000 Feet- Including the cities of Kenosha Mountains, Hot Sulphur Springs, Kremmling, Indian Peaks, Dillon, Eisenhower Tunnel, Fraser, East Slopes Southern Gore Range, Mount Evans, Laramie and Medicine Bow Mountains, Grand Lake, Cameron Pass, Granby, Breckenridge, Winter Park, Rocky Mountain National Park, Willow Creek Pass, Rabbit Ears Range, East Slopes Mosquito Range, Williams Fork Mountains, and Berthoud Pass 203 AM MDT Mon Aug 2 2021 ...FLASH FLOOD WATCH REMAINS IN EFFECT FROM NOON MDT TODAY THROUGH THIS EVENING... The Flash Flood Watch continues for * Portions of central and north central Colorado, including the following areas, in central Colorado, Grand and Summit Counties Below 9000 Feet and South and Southeast Grand/West Central and Southwest Boulder/Gilpin/Clear Creek/Summit/North and West Park Counties Above 9000 Feet. In north central Colorado, South and East Jackson/Larimer/North and Northeast Grand/Northwest Boulder Counties Above 9000 Feet. * From Noon MDT today through this evening. * Thunderstorms with locally heavy rainfall are expected to develop across the mountains Monday afternoon, and continue into the evening. Stronger storms will be capable of producing up to 1 inch of rain in 40 minutes. * The East Troublesome and Williams Fork burn scars will be especially susceptible to heavy rainfall, leading to quick runoff and debris and mud flows. PRECAUTIONARY/PREPAREDNESS ACTIONS... You should monitor later forecasts and be prepared to take action should Flash Flood Warnings be issued. && $$ Cooper
742 WGUS65 KBOU 030352 FFABOU Flood Watch National Weather Service Denver CO 952 PM MDT Mon Aug 2 2021 COZ032>035-037-030500- /O.EXP.KBOU.FF.A.0008.000000T0000Z-210803T0400Z/ /00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/ Grand and Summit Counties Below 9000 Feet-South and East Jackson/Larimer/North and Northeast Grand/Northwest Boulder Counties Above 9000 Feet-South and Southeast Grand/West Central and Southwest Boulder/Gilpin/Clear Creek/Summit/North and West Park Counties Above 9000 Feet-Larimer and Boulder Counties Between 6000 and 9000 Feet-Central and Southeast Park County- Including the cities of Winter Park, Hartsel, Rocky Mountain National Park, Laramie and Medicine Bow Mountains, Red Feather Lakes, Breckenridge, Williams Fork Mountains, Glendevey, Indian Peaks, Nederland, Eisenhower Tunnel, Kremmling, East Slopes Southern Gore Range, Mount Evans, Fairplay, Grand Lake, Cameron Pass, East Slopes Mosquito Range, Berthoud Pass, South Park, Granby, Kenosha Mountains, Estes Park, Willow Creek Pass, Hot Sulphur Springs, Dillon, Fraser, Lake George, and Rabbit Ears Range 952 PM MDT Mon Aug 2 2021 ...FLASH FLOOD WATCH WILL EXPIRE AT 10 PM MDT THIS EVENING... The Flash Flood Watch for Portions of central and north central Colorado, including the following areas, in central Colorado, Central and Southeast Park County, Grand and Summit Counties Below 9000 Feet and South and Southeast Grand/West Central and Southwest Boulder/Gilpin/Clear Creek/Summit/North and West Park Counties Above 9000 Feet. In north central Colorado, Larimer and Boulder Counties Between 6000 and 9000 Feet and South and East Jackson/Larimer/North and Northeast Grand/Northwest Boulder Counties Above 9000 Feet. will expire at 10 PM MDT this evening. The rainfall in the watch area continues to decrease at this time with only scattered light rain showers remaining. Flooding is no longer expected to pose a threat. Please continue to heed remaining road closures. $$ RJK
The office that day
Everything else NWS Denver/Boulder, CO issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 31, 6:48 PM MDT | Areal Flood Advisory | BOU | Douglas | 87 min |
Nearby
Flash Flood Watches in Colorado, 2021Every flash flood watch 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.