Alert archive / Colorado / Flash Flood Warnings in 2021

Flash Flood Warning 77, NWS Grand Junction, CO

August 3, 2021San Miguel County, Colorado

NWS Grand Junction, CO issued this flash flood warning at Aug 3, 2021, 3:21 PM MDT for San Miguel County, Colorado. It was in force for 104 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
Aug 3, 2021, 3:21 PM MDT (21:21 UTC)
Expired
Aug 3, 2021, 5:05 PM MDT
In force
104 min
Issued by
NWS Grand Junction, CO
Area
Storm-based polygon
Flood severity
None

County San Miguel County, CO

The radar

The Grand Junction radar (KGJX), 121 km from the middle of the area, began a volume at 21:24 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, 9.4 hours before the alert went out and 134 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 12:00Z on 2021-08-03Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 5 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 12:00Z on 2021-08-03The 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
5 J/kg
Mixed-layer CIN
-176 J/kg
Mixed-layer LCL
1792 m above ground
0-6 km bulk shear
6 kt
0-1 km storm-relative helicity
-5 m²/s²
0-3 km storm-relative helicity
48 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

591 
WGUS55 KGJT 032121
FFWGJT
COC113-032315-
/O.NEW.KGJT.FF.W.0077.210803T2121Z-210803T2315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Grand Junction CO
321 PM MDT Tue Aug 3 2021

The National Weather Service in Grand Junction has issued a

* Flash Flood Warning for...
  East Central San Miguel County in southwestern Colorado...

* Until 515 PM MDT.

* At 321 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 0.5 and 1 inch of rain 
  has 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...
  Sawpit, Fall Creek and Placerville.

This includes the following highways...
	Colorado 62 near mile marker 1.
	Colorado 145 between mile markers 76 and 87.

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.

&&

LAT...LON 3803 10811 3805 10811 3805 10809 3800 10797
      3798 10793 3795 10793 3793 10795 3792 10797
      3792 10800 3794 10801 3796 10804 3798 10807
      3801 10808 3802 10810

FLASH FLOOD...RADAR INDICATED

$$

ERW
1 follow-up statement
219 
WGUS75 KGJT 032305
FFSGJT

Flash Flood Statement
National Weather Service Grand Junction CO
505 PM MDT Tue Aug 3 2021

COC113-032315-
/O.CAN.KGJT.FF.W.0077.000000T0000Z-210803T2315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Miguel CO-
505 PM MDT Tue Aug 3 2021

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

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 1200 AM MDT Wednesday 
for portions of northwest Colorado, southwest Colorado and west 
central Colorado.

LAT...LON 3803 10811 3805 10811 3805 10809 3800 10797
      3798 10793 3795 10793 3793 10795 3792 10797
      3792 10800 3794 10801 3796 10804 3798 10807
      3801 10808 3802 10810

$$

ERW

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 2, 6:41 PM MDTSpecial Weather StatementGJT49 min
Aug 2, 7:44 PM MDTAreal Flood AdvisoryGJTGarfield, Mesa2 hr
Aug 2, 8:21 PM MDTAreal Flood AdvisoryGJTMesa114 min
Aug 2, 8:27 PM MDTFlash Flood Warning Considerable damage threatGJTEagle, Garfield2 hr
Aug 2, 8:43 PM MDTFlash Flood Warning Considerable damage threatGJTGarfield, Mesa2 hr
Aug 3, 9:32 AM MDTAreal Flood AdvisoryGJTEagle3 hr
Aug 3, 12:16 PM MDTFlash Flood Warning Considerable damage threatGJTSan Miguel88 min
Aug 3, 2:54 PM MDTFlash Flood Warning Considerable damage threatGJTEagle, Garfield111 min
Aug 3, 3:27 PM MDTFlash Flood Warning Considerable damage threatGJTEagle, Garfield, Pitkin2 hr
Aug 3, 4:04 PM MDTSpecial Weather StatementGJTSan Miguel41 min

Nearby

Flash Flood Warnings in Colorado, 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.