Alert archive / Colorado / Flash Flood Warnings in 2021

Flash Flood Warning 2, NWS Denver/Boulder, CO

May 31, 2021Grand County, Colorado

NWS Denver/Boulder, CO issued this flash flood warning at May 31, 2021, 3:36 PM MDT for Grand County, Colorado. It was in force for 84 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
May 31, 2021, 3:36 PM MDT (21:36 UTC)
Expired
May 31, 2021, 5:00 PM MDT
In force
84 min
Issued by
NWS Denver/Boulder, CO
Area
Storm-based polygon
Flood severity
None

County Grand County, CO

The radar

The Denver radar (KFTG), 126 km from the middle of the area, began a volume at 21:36 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, 9.6 hours before the alert went out and 227 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 2021-05-31Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 12:00Z on 2021-05-31The 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1713 m above ground
0-6 km bulk shear
18 kt
0-1 km storm-relative helicity
5 m²/s²
0-3 km storm-relative helicity
20 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

176 
WGUS55 KBOU 312136
FFWBOU
COC049-312300-
/O.NEW.KBOU.FF.W.0002.210531T2136Z-210531T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Denver CO
336 PM MDT Mon May 31 2021

The National Weather Service in Denver has issued a

* Flash Flood Warning for...
  South Central Grand County in north central Colorado...

* Until 500 PM MDT.

* At 336 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 0.5 and 1 inch of rain 
  has fallen. 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. Expect
           flooding along Darling and Kinney Creek

* Some locations that will experience flash flooding include...
  mainly rural areas of South Central Grand County

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy Rainfall will cause minor flooding of small creeks, streams, 
and ditches in the Williams Fork burn area. The heavy rains could 
also trigger rock slides or debris flows.

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

&&

LAT...LON 3985 10607 3988 10598 3977 10593 3979 10603

FLASH FLOOD...RADAR INDICATED

$$

Entrekin
1 follow-up statement
439 
WGUS75 KBOU 312253
FFSBOU

Flash Flood Statement
National Weather Service Denver CO
453 PM MDT Mon May 31 2021

COC049-312303-
/O.EXP.KBOU.FF.W.0002.000000T0000Z-210531T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Grand CO-
453 PM MDT Mon May 31 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 5 PM MDT THIS AFTERNOON FOR 
SOUTH CENTRAL GRAND COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures. Expect 
additional light rain showers through the early evening, but 
flooding impacts will be very low.

LAT...LON 3985 10607 3988 10598 3977 10593 3979 10603

$$

Entrekin

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.