Alert archive / Colorado / Flash Flood Warnings in 2021

Flash Flood Warning 23, NWS Grand Junction, CO

July 24, 2021Garfield County, Mesa County, Colorado

NWS Grand Junction, CO issued this flash flood warning at Jul 24, 2021, 1:49 PM MDT for Garfield County, Mesa County, Colorado. It was in force for 3 hr. 2 reports 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 24, 2021, 1:49 PM MDT (19:49 UTC)
Expired: Jul 24, 2021, 4:45 PM MDT
In force: 3 hr
Issued by: NWS Grand Junction, CO
Area: Storm-based polygon
Flood severity: None

Counties Garfield County, CO, Mesa County, CO

The radar

The Grand Junction radar (KGJX), 29 km from the middle of the area, began a volume at 19:49 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 24, 2:30 PM MDT	FLASH FLOOD	1 W Collbran, CO	EVIDENCE OF ROCKS, MUD AND WATER ALONG MAIN STREET IN COLLBRAN. SANDBAGS IN FRONT OF CERTAIN BUSINESSES. SPOTTER ALSO REPORTED 2 TREES BEING UPROOTED DUE TO FLASH FLOODING 2 MILES DOWN ON HIGHWAY 330.
Jul 24, 3:44 PM MDT	HEAVY RAIN 0.93	Collbran, CO	HEAVY RAIN FELL IN 2 HOURS.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Grand Junction, CO (KGJT), launched 12:00Z, 7.8 hours before the alert went out and 41 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: 19 J/kg
Mixed-layer CIN: -266 J/kg
Mixed-layer LCL: 1844 m above ground
0-6 km bulk shear: 5 kt
0-1 km storm-relative helicity: 40 m²/s²
0-3 km storm-relative helicity: 94 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

019 
WGUS55 KGJT 241949
FFWGJT
COC045-077-242245-
/O.NEW.KGJT.FF.W.0023.210724T1949Z-210724T2245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Grand Junction CO
149 PM MDT Sat Jul 24 2021

The National Weather Service in Grand Junction has issued a

* Flash Flood Warning for...
  South Central Garfield County in west central Colorado...
  Northeastern Mesa County in west central Colorado...

* Until 445 PM MDT.

* At 149 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 0.7 and 0.9 inches of 
  rain have fallen. Additional rainfall amounts of 0.5 to 1 inch 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, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Collbran.

This includes the following streams and drainages...
  Salt Creek, West Fork Kimball Creek, Pete and Bill Creek, Little 
  Horsethief Creek, Buzzard Creek, Spring Creek, Grove Creek, Big 
  Creek, Plateau Creek, Wallace Creek, North Fork Wallace Creek, 
  East Hawxhurst Creek, Horsethief Creek, Cottonwood Creek, Kimball 
  Creek, Little Alkali Creek and Alkali Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

In hilly terrain there are hundreds of low water crossings which are 
potentially dangerous in heavy rain. Do not attempt to cross flooded 
roads. Find an alternate route.

&&

LAT...LON 3930 10824 3933 10820 3935 10816 3937 10815
      3938 10814 3938 10813 3940 10810 3941 10803
      3936 10794 3929 10791 3928 10791 3926 10791
      3924 10793 3922 10798 3919 10807 3923 10810
      3926 10812 3928 10816 3929 10819

FLASH FLOOD...RADAR INDICATED

$$

JDC

2 follow-up statements

403 
WGUS75 KGJT 242028
FFSGJT

Flash Flood Statement
National Weather Service Grand Junction CO
228 PM MDT Sat Jul 24 2021

COC045-077-242245-
/O.CON.KGJT.FF.W.0023.000000T0000Z-210724T2245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Garfield CO-Mesa CO-
228 PM MDT Sat Jul 24 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 445 PM MDT THIS 
AFTERNOON FOR SOUTH CENTRAL GARFIELD AND NORTHEASTERN MESA 
COUNTIES...

At 228 PM MDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. Between 0.7 and 1 inch of rain has 
fallen. Additional rainfall amounts of 0.1 to 0.5 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, urban areas,
         highways, streets and underpasses as well as other poor
         drainage and low-lying areas.

Some locations that will experience flash flooding include...
  Collbran.

This includes the following streams and drainages...
  Salt Creek, West Fork Kimball Creek, Pete and Bill Creek, Little 
  Horsethief Creek, Buzzard Creek, Spring Creek, Grove Creek, Big 
  Creek, Plateau Creek, Wallace Creek, North Fork Wallace Creek, 
  East Hawxhurst Creek, Horsethief Creek, Cottonwood Creek, Kimball 
  Creek, Little Alkali Creek and Alkali Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

In hilly terrain there are hundreds of low water crossings which are 
potentially dangerous in heavy rain. Do not attempt to cross flooded 
roads. Find an alternate route.

&&

LAT...LON 3930 10824 3933 10820 3935 10816 3937 10815
      3938 10814 3938 10813 3940 10810 3941 10803
      3936 10794 3929 10791 3928 10791 3926 10791
      3924 10793 3922 10798 3919 10807 3923 10810
      3926 10812 3928 10816 3929 10819

FLASH FLOOD...RADAR INDICATED

$$

JDC

745 
WGUS75 KGJT 242235
FFSGJT

Flash Flood Statement
National Weather Service Grand Junction CO
435 PM MDT Sat Jul 24 2021

COC045-077-242245-
/O.EXP.KGJT.FF.W.0023.000000T0000Z-210724T2245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Garfield CO-Mesa CO-
435 PM MDT Sat Jul 24 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 445 PM MDT THIS AFTERNOON FOR 
SOUTH CENTRAL GARFIELD AND NORTHEASTERN MESA COUNTIES...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

LAT...LON 3930 10824 3933 10820 3935 10816 3937 10815
      3938 10814 3938 10813 3940 10810 3941 10803
      3936 10794 3929 10791 3928 10791 3926 10791
      3924 10793 3922 10798 3919 10807 3923 10810
      3926 10812 3928 10816 3929 10819

$$

JDC

The office that day

Everything else NWS Grand Junction, CO issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 23, 6:04 PM MDT	Areal Flood Advisory	GJT	Rio Blanco	116 min
Jul 23, 6:11 PM MDT	Areal Flood Advisory	GJT	Delta	2 hr
Jul 23, 6:17 PM MDT	Special Weather Statement	GJT	Delta	28 min
Jul 23, 6:37 PM MDT	Special Weather Statement	GJT		38 min
Jul 23, 7:04 PM MDT	Areal Flood Advisory	GJT	Mesa, Montrose	109 min
Jul 23, 7:14 PM MDT	Areal Flood Advisory	GJT	Garfield, Mesa	3 hr
Jul 23, 8:44 PM MDT	Areal Flood Advisory	GJT	Dolores, San Miguel	2 hr
Jul 24, 3:51 AM MDT	Flash Flood Watch	GJT	Archuleta, Delta, Dolores, Eagle, Garfield, Gunnison and 12 more	17 hr
Jul 24, 11:57 AM MDT	Special Weather Statement	GJT	Garfield	48 min
Jul 24, 12:34 PM MDT	Areal Flood Advisory	GJT	Delta, Gunnison, Mesa, Pitkin	3 hr
Jul 24, 12:41 PM MDT	Special Weather Statement	GJT	Delta	49 min
Jul 24, 1:30 PM MDT	Special Weather Statement	GJT	Delta	30 min
Jul 24, 1:30 PM MDT	Special Weather Statement	GJT	Garfield	45 min
Jul 24, 1:32 PM MDT	Special Weather Statement	GJT	Ouray	28 min
Jul 24, 1:36 PM MDT	Areal Flood Advisory	GJT	Garfield, Mesa	13 min
Jul 24, 1:46 PM MDT	Areal Flood Advisory	GJT	San Miguel	3 hr
Jul 24, 2:09 PM MDT	Areal Flood Advisory	GJT	San Miguel	55 min
Jul 24, 2:15 PM MDT	Special Weather Statement	GJT	Montezuma	30 min
Jul 24, 2:34 PM MDT	Areal Flood Advisory	GJT	Montrose, San Miguel	30 min
Jul 24, 2:45 PM MDT	Special Weather Statement	GJT	Montezuma	15 min
Jul 24, 3:03 PM MDT	Flash Flood Warning	GJT	Montrose, San Miguel	3 hr
Jul 24, 3:12 PM MDT	Flash Flood Warning Considerable damage threat	GJT	Garfield, Mesa	82 min
Jul 24, 3:27 PM MDT	Areal Flood Advisory	GJT	Montezuma	2 hr
Jul 24, 3:28 PM MDT	Flash Flood Warning Considerable damage threat	GJT	Eagle, Garfield	69 min
Jul 24, 3:45 PM MDT	Areal Flood Advisory	GJT	Montrose	4 min
Jul 24, 3:47 PM MDT	Flash Flood Warning	GJT	Montrose	3 hr
Jul 24, 3:55 PM MDT	Flash Flood Warning	GJT	Mesa, Montrose	3 hr

Nearby

Flash Flood Warnings in Colorado, 2021 Every 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.