Alert archive / Utah / Flash Flood Warnings in 2021

Flash Flood Warning 53, NWS Grand Junction, CO

July 28, 2021Grand County, San Juan County, Utah

NWS Grand Junction, CO issued this flash flood warning at Jul 28, 2021, 7:23 PM MDT for Grand County, San Juan County, Utah. It was in force for 3 hr. 4 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Jul 28, 2021, 7:23 PM MDT (01:23 UTC)
Expired
Jul 28, 2021, 10:30 PM MDT
In force
3 hr
Issued by
NWS Grand Junction, CO
Area
Storm-based polygon
Flood severity
None

Counties Grand County, UT, San Juan County, UT

The radar

The Grand Junction radar (KGJX), 133 km from the middle of the area, began a volume at 01:22 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.

What was reported inside it

TimeReportWhereRemark
Jul 28, 7:30 PM MDTHEAVY RAIN 0.7Moab, UT
Jul 28, 8:00 PM MDTFLASH FLOODMoab, UTNUMEROUS REPORTS OF FLASH FLOODING VIA SOCIAL MEDIA.
Jul 28, 8:53 PM MDTHEAVY RAIN 0.794 Sse Moab, UT
Jul 28, 9:00 PM MDTHEAVY RAIN 1.624 Se Moab, UT

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Grand Junction, CO (KGJT), launched 00:00Z, 1.4 hours before the alert went out and 115 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-pSkew-T log-p diagram, Grand Junction, CO at 00:00Z on 2021-07-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 405 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Grand Junction, CO at 00:00Z on 2021-07-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -5 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
405 J/kg
Mixed-layer CIN
-60 J/kg
Mixed-layer LCL
3067 m above ground
0-6 km bulk shear
19 kt
0-1 km storm-relative helicity
-5 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.

688 
WGUS55 KGJT 290123
FFWGJT
UTC019-037-290430-
/O.NEW.KGJT.FF.W.0053.210729T0123Z-210729T0430Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Grand Junction CO
723 PM MDT Wed Jul 28 2021

The National Weather Service in Grand Junction has issued a

* Flash Flood Warning for...
  South Central Grand County in east central Utah...
  Northern San Juan County in southeastern Utah...

* Until 1030 PM MDT.

* At 723 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 0.4 and 0.8 inches of 
  rain have 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, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Moab and Spanish Valley.

This includes the following streams and drainages...
  Mill Creek, Hunters Canyon, Pack Creek, Dry Fork, North Fork Mill 
  Creek and Kane Springs Canyon.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be aware of your surroundings and do not drive on flooded roads.

Flooding is occurring or is imminent. It is important to know where 
you are relative to streams, rivers, or creeks which can become 
killers in heavy rains. Campers and hikers should avoid streams or 
creeks.

&&

LAT...LON 3860 10978 3867 10968 3869 10955 3847 10935
      3845 10939 3838 10949 3850 10972

FLASH FLOOD...RADAR INDICATED

$$

JDC
2 follow-up statements
335 
WGUS75 KGJT 290227
FFSGJT

Flash Flood Statement
National Weather Service Grand Junction CO
827 PM MDT Wed Jul 28 2021

UTC019-037-290430-
/O.CON.KGJT.FF.W.0053.000000T0000Z-210729T0430Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Grand UT-San Juan UT-
827 PM MDT Wed Jul 28 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1030 PM MDT THIS 
EVENING FOR SOUTH CENTRAL GRAND AND NORTHERN SAN JUAN COUNTIES...

At 827 PM MDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. Between 1 and 2 inches of rain have 
fallen. Additional rainfall amounts of 0.1 to 0.2 inches are 
possible in the warned area. Flash flooding is ongoing in and around 
Moab, UT.

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...
  Moab and Spanish Valley.

This includes the following streams and drainages...
  Mill Creek, Hunters Canyon, Pack Creek, Dry Fork, Colorado River, 
  North Fork Mill Creek and Kane Springs Canyon.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be aware of your surroundings and do not drive on flooded roads.

Flooding is occurring or is imminent. It is important to know where 
you are relative to streams, rivers, or creeks which can become 
killers in heavy rains. Campers and hikers should avoid streams or 
creeks.

&&

LAT...LON 3860 10978 3867 10968 3869 10955 3847 10935
      3845 10939 3838 10949 3850 10972

FLASH FLOOD...RADAR INDICATED

$$

JDC
694 
WGUS75 KGJT 290422
FFSGJT

Flash Flood Statement
National Weather Service Grand Junction CO
1022 PM MDT Wed Jul 28 2021

UTC019-037-290432-
/O.EXP.KGJT.FF.W.0053.000000T0000Z-210729T0430Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Grand UT-San Juan UT-
1022 PM MDT Wed Jul 28 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 1030 PM MDT THIS EVENING FOR 
SOUTH CENTRAL GRAND AND NORTHERN SAN JUAN COUNTIES...

Flood waters have receded. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

LAT...LON 3860 10978 3867 10968 3869 10955 3847 10935
      3845 10939 3838 10949 3850 10972

$$

JDC

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 28, 6:32 PM MDTFlash Flood WarningGJTSan Juan75 min
Jul 28, 7:38 PM MDTAreal Flood WarningGJTGrand5 min
Jul 28, 7:43 PM MDTFlash Flood WarningGJTGrand3 hr
Jul 29, 5:39 PM MDTAreal Flood AdvisoryGJTSan Juan3 hr

Nearby

Flash Flood Warnings in Utah, 2021Every 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.