Alert archive / Colorado / Flash Flood Watches in 2021

Flash Flood Watch 2, NWS Denver/Boulder, CO

July 5, 20215 counties in Colorado

NWS Denver/Boulder, CO issued this flash flood watch at Jul 5, 2021, 3:13 AM MDT for 5 counties in Colorado. It took effect at Jul 5, 2021, 12:00 PM MDT. It was in force for 12 hr.

The area

The counties it named.

The facts

Issued
Jul 5, 2021, 3:13 AM MDT (09:13 UTC)
In effect from
Jul 5, 2021, 12:00 PM MDT
Expired
Jul 6, 2021, 12:00 AM MDT
In force
12 hr
Issued by
NWS Denver/Boulder, CO
Flood severity
None

Counties Boulder County, CO, Grand County, CO, Jackson County, CO, Larimer County, CO, Summit County, CO

The radar

The Denver radar (KFTG), 124 km from the middle of the area, began a volume at 09:14 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 00:00Z, 9.2 hours before the alert went out and 229 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-pSkew-T log-p diagram, Denver, CO at 00:00Z on 2021-07-05Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Denver, CO at 00:00Z on 2021-07-05The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -65 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
2682 m above ground
0-6 km bulk shear
21 kt
0-1 km storm-relative helicity
-65 m²/s²
0-3 km storm-relative helicity
75 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.1

Open this sounding in Storm Lab

The text

As transmitted.

490 
WGUS65 KBOU 050913
FFABOU

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service Denver CO
313 AM MDT Mon Jul 5 2021

.The flash flood threat will increase today due to slow moving 
thunderstorms, slightly greater moisture, and an increase in the 
number of thunderstorms. The main threat area will be across the 
East Troublesome, Williams Fork, Cameron Peak, and Calwood burn 
areas.

COZ032-033-035-052100-
/O.NEW.KBOU.FF.A.0002.210705T1800Z-210706T0600Z/
/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-Larimer and Boulder Counties Between
6000 and 9000 Feet-
Including the cities of Hot Sulphur Springs, Glendevey,
Kremmling, Nederland, Red Feather Lakes, Dillon, Fraser, Laramie
and Medicine Bow Mountains, Grand Lake, Cameron Pass, Granby,
Estes Park, Rocky Mountain National Park, Willow Creek Pass, and
Rabbit Ears Range
313 AM MDT Mon Jul 5 2021

...FLASH FLOOD WATCH IN EFFECT FROM NOON MDT TODAY THROUGH THIS 
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. 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.

* From Noon MDT today through this evening.

* Heavy rain will accompany slow moving thunderstorms this afternoon 
  and evening.

* Heavy rain may cause flashing flooding and debris flow in and near 
  the East Troublesome, Williams Fork, Cameron Peak, and Calwood 
  burn areas. Rapid increases in water in creeks and small drainages 
  could make roads become quickly impassable.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$

Meier
2 follow-up statements
483 
WGUS65 KBOU 052058
FFABOU

Flood Watch
National Weather Service Denver/Boulder CO
258 PM MDT Mon Jul 5 2021

.Thunderstorms are ongoing this afternoon with the stronger storms
producing heavy rainfall and flash flooding. Another round of
showers and storms will be possible tonight which the flash flood
risk continuing until midnight. The main threat area will be 
across the East Troublesome, Williams Fork, Cameron Peak, and 
Calwood burn areas.

COZ032-033-035-060600-
/O.CON.KBOU.FF.A.0002.000000T0000Z-210706T0600Z/
/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-
Larimer and Boulder Counties Between 6000 and 9000 Feet-
Including the cities of Dillon, Fraser, Granby, Grand Lake, 
Hot Sulphur Springs, Kremmling, Cameron Pass, 
Laramie and Medicine Bow Mountains, Rabbit Ears Range, 
Rocky Mountain National Park, Willow Creek Pass, Estes Park, 
Glendevey, Nederland, and Red Feather Lakes
258 PM MDT Mon Jul 5 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT UNTIL MIDNIGHT MDT
TONIGHT...

The Flash Flood Watch continues for

* Portions of central Colorado and north central Colorado, 
  including the following areas, in central Colorado, Grand and 
  Summit Counties Below 9000 Feet. In north central Colorado, 
  Rocky Mountain National Park and the Medicine Bow Range and 
  The Northern Front Range Foothills. 

* Until midnight MDT tonight

* Heavy rain will accompany slow moving thunderstorms this 
  afternoon and evening. 

* Heavy rain may cause flashing flooding and debris flow in and 
  near the East Troublesome, Williams Fork, Cameron Peak, and 
  Calwood burn areas. Rapid increases in water in creeks and 
  small drainages could make roads become quickly impassable. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action
should Flash Flood Warnings be issued.

&&

$$
825 
WGUS65 KBOU 060536
FFABOU

Flood Watch
National Weather Service Denver CO
1136 PM MDT Mon Jul 5 2021

COZ032-033-035-060645-
/O.EXP.KBOU.FF.A.0002.000000T0000Z-210706T0600Z/
/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-Larimer and Boulder Counties Between
6000 and 9000 Feet-
Including the cities of Hot Sulphur Springs, Glendevey,
Kremmling, Nederland, Red Feather Lakes, Dillon, Fraser, Laramie
and Medicine Bow Mountains, Grand Lake, Cameron Pass, Granby,
Estes Park, Rocky Mountain National Park, Willow Creek Pass, and
Rabbit Ears Range
1136 PM MDT Mon Jul 5 2021

...FLASH FLOOD WATCH WILL EXPIRE AT MIDNIGHT MDT TONIGHT...

The 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. 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 Midnight MDT tonight.

Flooding is no longer expected to pose a threat. Please continue to 
heed remaining road closures, including Colorado Highway 125 in 
Grand county.

$$

Meier

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 5, 1:29 PM MDTAreal Flood AdvisoryBOUPark91 min
Jul 5, 1:36 PM MDTAreal Flood AdvisoryBOUGrand84 min
Jul 5, 1:39 PM MDTFlash Flood WarningBOULarimer96 min
Jul 5, 1:53 PM MDTAreal Flood AdvisoryBOULarimer82 min
Jul 5, 2:00 PM MDTFlash Flood WarningBOUGrand90 min
Jul 5, 2:12 PM MDTFlash Flood WarningBOULarimer93 min
Jul 5, 2:22 PM MDTSpecial Weather StatementBOUTeller23 min
Jul 5, 2:23 PM MDTAreal Flood AdvisoryBOUPark97 min
Jul 5, 2:44 PM MDTSpecial Weather StatementBOUClear Creek31 min
Jul 5, 3:28 PM MDTFlash Flood WarningBOUGrand92 min
Jul 5, 4:18 PM MDTAreal Flood AdvisoryBOUClear Creek, Park87 min
Jul 5, 5:14 PM MDTAreal Flood AdvisoryBOUArapahoe, Douglas91 min
Jul 5, 5:31 PM MDTFlash Flood WarningBOUGrand89 min
Jul 5, 5:51 PM MDTSpecial Weather StatementBOUDenver24 min
Jul 5, 5:53 PM MDTAreal Flood AdvisoryBOUArapahoe97 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.