Alert archive / Utah / Flash Flood Warnings in 2021

Flash Flood Warning 50, NWS Grand Junction, CO

July 28, 2021San Juan County, Utah

NWS Grand Junction, CO issued this flash flood warning at Jul 28, 2021, 6:32 PM MDT for San Juan County, Utah. It was in force for 75 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 28, 2021, 6:32 PM MDT (00:32 UTC)
Expired
Jul 28, 2021, 7:47 PM MDT
In force
75 min
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), 184 km from the middle of the area, began a volume at 00:34 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, 0.5 hours before the alert went out and 178 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.

651 
WGUS55 KGJT 290032
FFWGJT
UTC037-290230-
/O.NEW.KGJT.FF.W.0050.210729T0032Z-210729T0230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in Grand Junction has issued a

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

* Until 830 PM MDT.

* At 632 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. The expected rainfall rate is 
  0.5 to 1 inch 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...
  Blanding.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3780 10946 3777 10934 3770 10939 3765 10937
      3760 10941 3761 10951 3774 10950

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...0.5-1 INCH IN 1 HOUR

$$

MMS
1 follow-up statement
524 
WGUS75 KGJT 290147
FFSGJT

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

UTC037-290157-
/O.CAN.KGJT.FF.W.0050.000000T0000Z-210729T0230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Juan UT-
747 PM MDT Wed Jul 28 2021

...FLASH FLOOD WARNING IS CANCELLED FOR EAST CENTRAL SAN JUAN 
COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

LAT...LON 3780 10946 3777 10934 3770 10939 3765 10937
      3760 10941 3761 10951 3774 10950

$$

MMS

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 28, 7:23 PM MDTFlash Flood WarningGJTGrand, San Juan3 hr
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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.