Alert archive / Colorado / Flash Flood Warnings in 2021

Flash Flood Warning 68, NWS Grand Junction, CO

July 31, 2021Pitkin County, Colorado

NWS Grand Junction, CO issued this flash flood warning at Jul 31, 2021, 5:48 PM MDT for Pitkin County, Colorado. It was in force for 117 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 31, 2021, 5:48 PM MDT (23:48 UTC)
Expired: Jul 31, 2021, 7:45 PM MDT
In force: 117 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), 81 km from the middle of the area, began a volume at 23:48 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, 11.8 hours before the alert went out and 104 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1449 m above ground
0-6 km bulk shear: 4 kt
0-1 km storm-relative helicity: 66 m²/s²
0-3 km storm-relative helicity: 112 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

705 
WGUS55 KGJT 312348
FFWGJT
COC097-010145-
/O.NEW.KGJT.FF.W.0068.210731T2348Z-210801T0145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Grand Junction CO
548 PM MDT Sat Jul 31 2021

The National Weather Service in Grand Junction has issued a

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

* Until 745 PM MDT.

* At 548 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, and streets and as well as other poor
           drainage and low-lying areas.

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

This includes the following highways...
	Colorado 133 between mile markers 49 and 56.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3917 10732 3917 10734 3920 10737 3923 10738
      3923 10731 3922 10726 3925 10724 3924 10720
      3920 10720 3914 10720 3915 10730 3916 10730
      3916 10731 3916 10732

FLASH FLOOD...RADAR INDICATED

$$

ERW

1 follow-up statement

292 
WGUS75 KGJT 010142
FFSGJT

Flash Flood Statement
National Weather Service Grand Junction CO
742 PM MDT Sat Jul 31 2021

COC097-010152-
/O.EXP.KGJT.FF.W.0068.000000T0000Z-210801T0145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Pitkin CO-
742 PM MDT Sat Jul 31 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 745 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 3917 10732 3917 10734 3920 10737 3923 10738
      3923 10731 3922 10726 3925 10724 3924 10720
      3920 10720 3914 10720 3915 10730 3916 10730
      3916 10731 3916 10732

$$

ERW

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 30, 6:23 PM MDT	Flash Flood Warning	GJT	Pitkin	112 min
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, 5:52 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.