Alert archive / Colorado / Flash Flood Warnings in 2021

Flash Flood Warning 49, NWS Grand Junction, CO

July 28, 2021Mesa County, Montrose County, Colorado

NWS Grand Junction, CO issued this flash flood warning at Jul 28, 2021, 5:22 PM MDT for Mesa County, Montrose County, Colorado. It was in force for 77 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: Jul 28, 2021, 5:22 PM MDT (23:22 UTC)
Expired: Jul 28, 2021, 6:39 PM MDT
In force: 77 min
Issued by: NWS Grand Junction, CO
Area: Storm-based polygon
Flood severity: None

Counties Mesa County, CO, Montrose County, CO

The radar

The Grand Junction radar (KGJX), 84 km from the middle of the area, began a volume at 23:22 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

Grand Junction, CO (KGJT), launched 12:00Z, 11.4 hours before the alert went out and 76 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: 68 J/kg
Mixed-layer CIN: -138 J/kg
Mixed-layer LCL: 1671 m above ground
0-6 km bulk shear: 10 kt
0-1 km storm-relative helicity: -38 m²/s²
0-3 km storm-relative helicity: 37 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

766 
WGUS55 KGJT 282322
FFWGJT
COC077-085-290230-
/O.NEW.KGJT.FF.W.0049.210728T2322Z-210729T0230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Grand Junction CO
522 PM MDT Wed Jul 28 2021

The National Weather Service in Grand Junction has issued a

* Flash Flood Warning for...
  Southwestern Mesa County in west central Colorado...
  West Central Montrose County in west central Colorado...

* Until 830 PM MDT.

* At 522 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. The expected rainfall rate is 
  0.8 to 1.2 inches in 1 hour. 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...
  mainly rural areas of Southwestern Mesa and West Central Montrose 
  Counties

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3856 10906 3859 10904 3858 10883 3855 10869
      3850 10869 3842 10875 3841 10882 3848 10906

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...0.8-1.2 INCHES IN 1 HOUR

$$

MMS

1 follow-up statement

696 
WGUS75 KGJT 290039
FFSGJT

Flash Flood Statement
National Weather Service Grand Junction CO
639 PM MDT Wed Jul 28 2021

COC077-085-290049-
/O.CAN.KGJT.FF.W.0049.000000T0000Z-210729T0230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Mesa CO-Montrose CO-
639 PM MDT Wed Jul 28 2021

...FLASH FLOOD WARNING IS CANCELLED FOR SOUTHWESTERN MESA AND WEST 
CENTRAL MONTROSE COUNTIES...

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

LAT...LON 3856 10906 3859 10904 3858 10883 3855 10869
      3850 10869 3842 10875 3841 10882 3848 10906

$$

MMS

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 27, 6:16 PM MDT	Special Weather Statement	GJT	La Plata	29 min
Jul 27, 7:28 PM MDT	Areal Flood Advisory	GJT	La Plata	3 hr
Jul 27, 8:58 PM MDT	Special Weather Statement	GJT	Montezuma	47 min
Jul 28, 1:54 PM MDT	Areal Flood Advisory	GJT	Dolores, Montezuma	3 hr
Jul 28, 2:08 PM MDT	Flash Flood Watch	GJT	Eagle, Garfield, Moffat, Pitkin, Rio Blanco, Routt	8 hr
Jul 28, 2:14 PM MDT	Flash Flood Warning	GJT	San Miguel	3 hr
Jul 28, 2:28 PM MDT	Flash Flood Watch	GJT	Archuleta, Delta, Dolores, Eagle, Garfield, Gunnison and 12 more	34 hr
Jul 28, 2:28 PM MDT	Flash Flood Watch	GJT	Archuleta, Delta, Dolores, Eagle, Garfield, Gunnison and 12 more	58 hr
Jul 28, 2:35 PM MDT	Areal Flood Advisory	GJT	Rio Blanco	3 hr
Jul 28, 3:08 PM MDT	Areal Flood Advisory	GJT	Rio Blanco	3 hr
Jul 28, 3:14 PM MDT	Special Weather Statement	GJT	Rio Blanco	46 min
Jul 28, 3:19 PM MDT	Flash Flood Warning	GJT	San Miguel	3 hr
Jul 28, 3:40 PM MDT	Special Weather Statement	GJT	Ouray	50 min
Jul 28, 3:47 PM MDT	Flash Flood Warning	GJT	Rio Blanco	2 hr
Jul 28, 3:56 PM MDT	Special Weather Statement	GJT	Archuleta	49 min
Jul 28, 4:04 PM MDT	Special Weather Statement	GJT	La Plata	26 min
Jul 28, 4:08 PM MDT	Special Weather Statement	GJT	Montrose	22 min
Jul 28, 4:28 PM MDT	Special Weather Statement	GJT	Garfield	32 min
Jul 28, 4:47 PM MDT	Areal Flood Advisory	GJT	Mesa	3 hr
Jul 28, 5:07 PM MDT	Special Weather Statement	GJT		23 min
Jul 28, 5:25 PM MDT	Severe Thunderstorm Warning	GJT	Mesa, Montrose	35 min
Jul 28, 5:31 PM MDT	Severe Thunderstorm Warning	GJT	Mesa	29 min

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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.