Alert archive / Colorado / Flash Flood Warnings in 2021

Flash Flood Warning 47, NWS Grand Junction, CO

July 28, 2021San Miguel County, Colorado

NWS Grand Junction, CO issued this flash flood warning at Jul 28, 2021, 3:19 PM MDT for San Miguel County, Colorado. It was in force for 3 hr. 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, 3:19 PM MDT (21:19 UTC)
Expired: Jul 28, 2021, 6:15 PM MDT
In force: 3 hr
Issued by: NWS Grand Junction, CO
Area: Storm-based polygon
Flood severity: None

County San Miguel County, CO

The radar

The Grand Junction radar (KGJX), 113 km from the middle of the area, began a volume at 21:22 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, 9.3 hours before the alert went out and 125 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.

457 
WGUS55 KGJT 282119
FFWGJT
COC113-290015-
/O.NEW.KGJT.FF.W.0047.210728T2119Z-210729T0015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in Grand Junction has issued a

* Flash Flood Warning for...
  North Central San Miguel County in southwestern Colorado...

* Until 615 PM MDT.

* At 319 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 0.5 and 1 inch of rain 
  has 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...
  mainly rural areas of North Central San Miguel County

This includes the following highways...
	Colorado 145 between mile markers 86 and 97.

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 3803 10807 3801 10809 3795 10812 3795 10815
      3799 10819 3805 10823 3813 10824 3814 10821
      3812 10819 3807 10814

FLASH FLOOD...RADAR INDICATED

$$

ERW

1 follow-up statement

979 
WGUS75 KGJT 290007 RRA
FFSGJT

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

COC113-290017-
/O.EXP.KGJT.FF.W.0047.000000T0000Z-210729T0015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Miguel CO-
607 PM MDT Wed Jul 28 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 615 PM MDT THIS EVENING FOR 
NORTH CENTRAL SAN MIGUEL COUNTY...

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

LAT...LON 3803 10807 3801 10809 3795 10812 3795 10815
      3799 10819 3805 10823 3813 10824 3814 10821
      3812 10819 3807 10814

$$

ERW

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, 3:40 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, 5:22 PM MDT	Flash Flood Warning	GJT	Mesa, Montrose	77 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.