Alert archive / Colorado / Flash Flood Warnings in 2021

Flash Flood Warning 18, NWS Grand Junction, CO

July 22, 2021La Plata County, Montezuma County, Colorado

NWS Grand Junction, CO issued this flash flood warning at Jul 22, 2021, 4:30 PM MDT for La Plata County, Montezuma County, Colorado. It was in force for 6 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 22, 2021, 4:30 PM MDT (22:30 UTC)
Expired: Jul 22, 2021, 4:36 PM MDT
In force: 6 min
Issued by: NWS Grand Junction, CO
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

Counties La Plata County, CO, Montezuma County, CO

The radar

The Grand Junction radar (KGJX), 196 km from the middle of the area, began a volume at 22:29 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, 10.5 hours before the alert went out and 206 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: 1949 m above ground
0-6 km bulk shear: 4 kt
0-1 km storm-relative helicity: 42 m²/s²
0-3 km storm-relative helicity: -22 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

275 
WGUS55 KGJT 222230
FFWGJT
COC067-083-230030-
/O.NEW.KGJT.FF.W.0018.210722T2230Z-210723T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Grand Junction CO
430 PM MDT Thu Jul 22 2021

The National Weather Service in Grand Junction has issued a

* Flash Flood Warning for...
  The East Canyon Fire Burn Area in...
  Western La Plata County in southwestern Colorado...
  East Central Montezuma County in southwestern Colorado...

* Until 630 PM MDT.

* At 430 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain over the East Canyon Fire Burn Area. Flash flooding is 
  ongoing or expected to begin shortly.

Excessive rainfall over the burn scar will result in debris flow 
moving through the East Canyon Burn Area including County Road 105. 
The debris flow can consist of rock, mud, vegetation and other loose 
materials.

  HAZARD...Life threatening flash flooding. Thunderstorms
           producing flash flooding in and around the East Canyon
           Fire Burn Area.

  SOURCE...Radar.

  IMPACT...Life threatening flash flooding of areas in and around
           the East Canyon Fire Burn Area.

* Some locations that will experience flash flooding include...
  mainly rural areas of Western La Plata and East Central Montezuma 
  Counties

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This is a life threatening situation. Heavy rainfall will cause 
extensive and severe flash flooding of creeks...streams...and 
ditches in the East Canyon Fire Burn Area. Severe debris flows can 
also be anticipated across roads. Roads and driveways may be washed 
away in places. If you encounter flood waters...climb to safety.

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

&&

LAT...LON 3727 10824 3730 10822 3731 10822 3733 10821
      3733 10820 3733 10819 3728 10819 3724 10822

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

NL

1 follow-up statement

319 
WGUS75 KGJT 222236
FFSGJT

Flash Flood Statement
National Weather Service Grand Junction CO
436 PM MDT Thu Jul 22 2021

COC067-083-222246-
/O.CAN.KGJT.FF.W.0018.000000T0000Z-210723T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
La Plata CO-Montezuma CO-
436 PM MDT Thu Jul 22 2021

...FLASH FLOOD WARNING FOR THE EAST CANYON FIRE BURN AREA IS 
CANCELLED FOR WESTERN LA PLATA AND EAST CENTRAL MONTEZUMA COUNTIES...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat.

A Flash Flood Watch remains in effect until 1200 AM MDT Friday for a 
portion of southwest Colorado.

LAT...LON 3727 10824 3730 10822 3731 10822 3733 10821
      3733 10820 3733 10819 3728 10819 3724 10822

$$

MDA

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 21, 6:19 PM MDT	Special Weather Statement	GJT	Montrose	41 min
Jul 21, 6:37 PM MDT	Areal Flood Advisory	GJT	Delta, Mesa, Montrose	2 hr
Jul 22, 2:38 AM MDT	Areal Flood Advisory	GJT	Dolores	3 hr
Jul 22, 1:50 PM MDT	Flash Flood Watch	GJT	Archuleta, Delta, Dolores, Eagle, Garfield, Gunnison and 11 more	36 hr
Jul 22, 2:23 PM MDT	Special Weather Statement	GJT	Pitkin	52 min
Jul 22, 3:46 PM MDT	Areal Flood Advisory	GJT	Eagle	3 hr
Jul 22, 4:10 PM MDT	Areal Flood Advisory	GJT	Garfield	3 hr
Jul 22, 4:36 PM MDT	Flash Flood Warning Considerable damage threat	GJT	Eagle, Garfield	3 hr
Jul 22, 5:07 PM MDT	Flash Flood Warning	GJT	Eagle, Garfield	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.