Alert archive / Colorado / Flash Flood Warnings in 2021

Flash Flood Warning 36, NWS Grand Junction, CO

July 25, 2021Mesa County, Colorado

NWS Grand Junction, CO issued this flash flood warning at Jul 25, 2021, 7:19 PM MDT for Mesa 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 25, 2021, 7:19 PM MDT (01:19 UTC)
Expired: Jul 25, 2021, 10:30 PM MDT
In force: 3 hr
Issued by: NWS Grand Junction, CO
Area: Storm-based polygon
Flood severity: None

County Mesa County, CO

The radar

The Grand Junction radar (KGJX), 11 km from the middle of the area, began a volume at 01:19 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, 1.3 hours before the alert went out and 24 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: 126 J/kg
Mixed-layer CIN: -77 J/kg
Mixed-layer LCL: 2890 m above ground
0-6 km bulk shear: 9 kt
0-1 km storm-relative helicity: 4 m²/s²
0-3 km storm-relative helicity: 11 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

516 
WGUS55 KGJT 260119
FFWGJT
COC077-260430-
/O.NEW.KGJT.FF.W.0036.210726T0119Z-210726T0430Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Grand Junction CO
719 PM MDT Sun Jul 25 2021

The National Weather Service in Grand Junction has issued a

* Flash Flood Warning for...
  North Central Mesa County in west central Colorado...

* Until 1030 PM MDT.

* At 719 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. The expected rainfall rate is 
  0.8 to 1.3 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 North Central Mesa County

This includes the following highways...
	Interstate 70 in Colorado between mile markers 51 and 57.
	Colorado 65 between mile markers 52 and 59.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Please report observed flooding to local emergency services or law 
enforcement and request they pass this information to the National 
Weather Service when you can do so safely.

&&

LAT...LON 3909 10823 3916 10823 3923 10831 3928 10827
      3921 10815 3909 10814

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...0.8-1.3 INCHES IN 1 HOUR

$$

NL

1 follow-up statement

841 
WGUS75 KGJT 260429
FFSGJT

Flash Flood Statement
National Weather Service Grand Junction CO
1029 PM MDT Sun Jul 25 2021

COC077-260439-
/O.EXP.KGJT.FF.W.0036.000000T0000Z-210726T0430Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Mesa CO-
1029 PM MDT Sun Jul 25 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 1030 PM MDT THIS EVENING FOR 
NORTH CENTRAL MESA COUNTY...

The heavy rain has ended. Minor flooding may continue into the early 
morning hours as the water continues to recede. Please continue to 
heed remaining road closures.

LAT...LON 3909 10823 3916 10823 3923 10831 3928 10827
      3921 10815 3909 10814

$$

15

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 25, 6:03 PM MDT	Special Weather Statement	GJT		42 min
Jul 25, 6:51 PM MDT	Flash Flood Warning Considerable damage threat	GJT	Garfield, Mesa	114 min
Jul 25, 7:39 PM MDT	Flash Flood Warning Considerable damage threat	GJT	Eagle, Garfield	81 min
Jul 25, 8:03 PM MDT	Special Weather Statement	GJT	Mesa	42 min
Jul 25, 8:42 PM MDT	Areal Flood Advisory	GJT	Mesa	3 hr
Jul 25, 11:03 PM MDT	Areal Flood Advisory	GJT	Mesa	2 hr
Jul 25, 11:35 PM MDT	Flash Flood Warning	GJT	Mesa	115 min
Jul 26, 12:03 PM MDT	Flash Flood Watch	GJT	Delta, Dolores, Eagle, Garfield, Mesa, Moffat and 6 more	10 hr
Jul 26, 4:06 PM MDT	Areal Flood Advisory	GJT	La Plata	3 hr
Jul 26, 4:37 PM MDT	Areal Flood Advisory	GJT	Montezuma	3 hr
Jul 26, 5:14 PM MDT	Areal Flood Advisory	GJT	Dolores	3 hr
Jul 26, 5:50 PM MDT	Flash Flood Warning	GJT	Mesa, Montrose	114 min
Jul 26, 5:52 PM MDT	Special Weather Statement	GJT		38 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.