Alert archive / Utah / Flash Flood Warnings in 2021

Flash Flood Warning 40, NWS Grand Junction, CO

July 26, 2021San Juan County, Utah

NWS Grand Junction, CO issued this flash flood warning at Jul 26, 2021, 6:10 PM MDT for San Juan County, Utah. 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 26, 2021, 6:10 PM MDT (00:10 UTC)
Expired
Jul 26, 2021, 9:15 PM MDT
In force
3 hr
Issued by
NWS Grand Junction, CO
Area
Storm-based polygon
Flood severity
None

County San Juan County, UT

The radar

The Grand Junction radar (KGJX), 167 km from the middle of the area, began a volume at 00:11 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, 0.2 hours before the alert went out and 157 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 2021-07-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 143 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 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 2021-07-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 15 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
143 J/kg
Mixed-layer CIN
-69 J/kg
Mixed-layer LCL
3158 m above ground
0-6 km bulk shear
8 kt
0-1 km storm-relative helicity
15 m²/s²
0-3 km storm-relative helicity
70 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

791 
WGUS55 KGJT 270010
FFWGJT
UTC037-270315-
/O.NEW.KGJT.FF.W.0040.210727T0010Z-210727T0315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Grand Junction CO
610 PM MDT Mon Jul 26 2021

The National Weather Service in Grand Junction has issued a

* Flash Flood Warning for...
  East Central San Juan County in southeastern Utah...

* Until 915 PM MDT.

* At 610 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 0.7 and 1 inch of rain 
  has fallen. The expected rainfall rate is 1 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 East Central San Juan County including State 
  Road 211 northwest of Monticello.

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.

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 3792 10957 3800 10956 3807 10955 3802 10945
      3790 10947

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

$$

NL
1 follow-up statement
738 
WGUS75 KGJT 270310
FFSGJT

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

UTC037-270320-
/O.EXP.KGJT.FF.W.0040.000000T0000Z-210727T0315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Juan UT-
910 PM MDT Mon Jul 26 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 915 PM MDT THIS EVENING FOR 
EAST CENTRAL SAN JUAN COUNTY...

Flood waters have receded. 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 1000 PM MDT for a 
portion of southeast Utah.

LAT...LON 3792 10957 3800 10956 3807 10955 3802 10945
      3790 10947

$$

15

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 26, 6:11 PM MDTFlash Flood WarningGJTSan Juan3 hr
Jul 26, 6:21 PM MDTFlash Flood WarningGJTSan Juan3 hr
Jul 26, 7:07 PM MDTAreal Flood AdvisoryGJTGrand3 hr
Jul 26, 7:44 PM MDTFlash Flood WarningGJTGrand3 hr
Jul 26, 7:55 PM MDTSpecial Weather StatementGJTSan Juan50 min
Jul 26, 9:32 PM MDTAreal Flood AdvisoryGJTSan Juan118 min
Jul 27, 12:47 PM MDTAreal Flood AdvisoryGJTSan Juan3 hr
Jul 27, 1:27 PM MDTAreal Flood AdvisoryGJTGrand24 min
Jul 27, 1:51 PM MDTFlash Flood WarningGJTGrand88 min
Jul 27, 2:29 PM MDTAreal Flood AdvisoryGJTSan Juan2 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.