Alert archive / Colorado / Flash Flood Warnings in 2021

Flash Flood Warning 64, NWS Grand Junction, CO

July 30, 2021Pitkin County, Colorado

NWS Grand Junction, CO issued this flash flood warning at Jul 30, 2021, 6:23 PM MDT for Pitkin County, Colorado. It was in force for 112 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 30, 2021, 6:23 PM MDT (00:23 UTC)
Expired: Jul 30, 2021, 8:15 PM MDT
In force: 112 min
Issued by: NWS Grand Junction, CO
Area: Storm-based polygon
Flood severity: None

County Pitkin County, CO

The radar

The Grand Junction radar (KGJX), 85 km from the middle of the area, began a volume at 00:26 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 00:00Z, 0.4 hours before the alert went out and 109 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: 153 J/kg
Mixed-layer CIN: -45 J/kg
Mixed-layer LCL: 2676 m above ground
0-6 km bulk shear: 11 kt
0-1 km storm-relative helicity: -27 m²/s²
0-3 km storm-relative helicity: 36 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

447 
WGUS55 KGJT 310023
FFWGJT
COC097-310215-
/O.NEW.KGJT.FF.W.0064.210731T0023Z-210731T0215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Grand Junction CO
623 PM MDT Fri Jul 30 2021

The National Weather Service in Grand Junction has issued a

* Flash Flood Warning for...
  West Central Pitkin County in west central Colorado...

* Until 815 PM MDT.

* At 623 PM MDT, Doppler radar indicated additional thunderstorms 
  developing West of Redstone producing moderate to heavy rainfall 
  rates.  Areas along Highway 133 near Redstone have already 
  experienced mud and debris flows and additional rainfall should 
  continue this threat. Between 0.6 and 1 inch of rain has fallen. 
  The expected rainfall rate is 0.8 to 1.2 inches in 1 hour. Flash 
  flooding is already occurring.

  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...
   Areas along Highway 133 near Redstone. 

This includes the following highways...
	Colorado 133 between mile markers 48 and 54.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3922 10722 3922 10721 3913 10726 3914 10729
      3923 10724

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

$$

15

1 follow-up statement

470 
WGUS75 KGJT 310213
FFSGJT

Flash Flood Statement
National Weather Service Grand Junction CO
813 PM MDT Fri Jul 30 2021

COC097-310223-
/O.EXP.KGJT.FF.W.0064.000000T0000Z-210731T0215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Pitkin CO-
813 PM MDT Fri Jul 30 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 815 PM MDT THIS EVENING FOR 
WEST CENTRAL PITKIN COUNTY...

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

A Flash Flood Watch remains in effect until 1200 AM MDT for portions 
of northwest Colorado and west central Colorado.

A Flash Flood Watch remains in effect until 1200 AM MDT for portions 
of northwest Colorado and west central Colorado.

LAT...LON 3922 10722 3922 10721 3913 10726 3914 10729
      3923 10724

$$

ERW

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 30, 6:29 PM MDT	Special Weather Statement	GJT	Pitkin	31 min
Jul 30, 7:26 PM MDT	Special Weather Statement	GJT		34 min
Jul 30, 7:37 PM MDT	Severe Thunderstorm Warning	GJT	Mesa	23 min
Jul 30, 7:46 PM MDT	Areal Flood Advisory	GJT	Garfield	119 min
Jul 30, 7:52 PM MDT	Areal Flood Advisory	GJT	Garfield	113 min
Jul 30, 7:55 PM MDT	Areal Flood Advisory	GJT	Mesa, Montrose	3 hr
Jul 30, 8:00 PM MDT	Severe Thunderstorm Warning	GJT	Mesa	30 min
Jul 30, 9:04 PM MDT	Special Weather Statement	GJT	Mesa	26 min
Jul 30, 9:28 PM MDT	Special Weather Statement	GJT	Mesa	32 min
Jul 30, 10:44 PM MDT	Areal Flood Advisory	GJT	Mesa	2 hr
Jul 30, 11:14 PM MDT	Areal Flood Advisory	GJT	Mesa	3 hr
Jul 31, 12:13 AM MDT	Areal Flood Advisory	GJT	Mesa	3 hr
Jul 31, 12:30 AM MDT	Areal Flood Advisory	GJT	Moffat, Rio Blanco	3 hr
Jul 31, 1:08 PM MDT	Special Weather Statement	GJT		22 min
Jul 31, 2:45 PM MDT	Flash Flood Warning	GJT	San Miguel	2 hr
Jul 31, 3:00 PM MDT	Special Weather Statement	GJT	San Miguel	30 min
Jul 31, 3:50 PM MDT	Flash Flood Warning Considerable damage threat	GJT	Eagle, Garfield	115 min
Jul 31, 4:16 PM MDT	Flash Flood Warning Considerable damage threat	GJT	Garfield, Mesa	104 min
Jul 31, 4:32 PM MDT	Areal Flood Advisory	GJT	Dolores, Montezuma	118 min
Jul 31, 5:48 PM MDT	Flash Flood Warning	GJT	Pitkin	117 min
Jul 31, 5:52 PM MDT	Areal Flood Advisory	GJT	Rio Blanco	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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.