Alert archive / Colorado / Flash Flood Warnings in 2021

Flash Flood Warning 39, NWS Grand Junction, CO

July 26, 2021Mesa County, Montrose County, Colorado

NWS Grand Junction, CO issued this flash flood warning at Jul 26, 2021, 5:50 PM MDT for Mesa County, Montrose County, Colorado. It was in force for 114 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 26, 2021, 5:50 PM MDT (23:50 UTC)
Expired: Jul 26, 2021, 7:44 PM MDT
In force: 114 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), 83 km from the middle of the area, began a volume at 23:50 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 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: 3 J/kg
Mixed-layer CIN: -335 J/kg
Mixed-layer LCL: 1886 m above ground
0-6 km bulk shear: 10 kt
0-1 km storm-relative helicity: -9 m²/s²
0-3 km storm-relative helicity: 88 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

413 
WGUS55 KGJT 262350
FFWGJT
COC077-085-270300-
/O.NEW.KGJT.FF.W.0039.210726T2350Z-210727T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Grand Junction CO
550 PM MDT Mon Jul 26 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 900 PM MDT.

* At 550 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across 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...
  Uravan.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3859 10900 3867 10884 3847 10870 3837 10869
      3832 10884

FLASH FLOOD...RADAR INDICATED

$$

MMS

1 follow-up statement

729 
WGUS75 KGJT 270144
FFSGJT

Flash Flood Statement
National Weather Service Grand Junction CO
744 PM MDT Mon Jul 26 2021

COC077-085-270154-
/O.CAN.KGJT.FF.W.0039.000000T0000Z-210727T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Mesa CO-Montrose CO-
744 PM MDT Mon Jul 26 2021

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

The threat for heavy rain has ended and flooding is no longer 
expected to pose a threat. However, additional showers capable of 
producing light to moderate rain will be possible for the next few 
hours. Please continue to heed remaining road closures.

A Flash Flood Watch remains in effect until 1000 PM MDT for portions 
of west-central and southwest Colorado.

LAT...LON 3859 10900 3867 10884 3847 10870 3837 10869
      3832 10884

$$

MMS

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, 7:19 PM MDT	Flash Flood Warning	GJT	Mesa	3 hr
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, 5:52 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.