Alert archive / Colorado / Flash Flood Warnings in 2021

Flash Flood Warning 77, NWS Denver/Boulder, CO

August 19, 2021Phillips County, Colorado

NWS Denver/Boulder, CO issued this flash flood warning at Aug 19, 2021, 5:09 PM MDT for Phillips County, Colorado. It was in force for 3 hr. 6 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: Aug 19, 2021, 5:09 PM MDT (23:09 UTC)
Expired: Aug 19, 2021, 8:15 PM MDT
In force: 3 hr
Issued by: NWS Denver/Boulder, CO
Area: Storm-based polygon
Flood severity: None

County Phillips County, CO

The radar

The Goodland radar (KGLD), 133 km from the middle of the area, began a volume at 23:12 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

Time	Report	Where	Remark
Aug 19, 7:37 PM MDT	FLASH FLOOD	Holyoke, CO	SIGNIFICANT STREET FLOODING INCLUDING MAIN STREET IN AND NEAR HOLYOKE.
Aug 19, 7:55 PM MDT	HEAVY RAIN 3.4	1 E Holyoke, CO
Aug 19, 7:58 PM MDT	FLASH FLOOD	1 E Holyoke, CO	SEVERAL HOUSES HAD WATER RISE UP TO THE FRONT DOORS.
Aug 19, 8:05 PM MDT	FLASH FLOOD	5 Wsw Pleasant Valley, CO	SIGNIFICANT FLASH FLOODING 6 MILES EAST OF HOLYOKE ON U.S. HIGHWAY 6.
Aug 19, 8:08 PM MDT	HEAVY RAIN 5.29	5 S Holyoke, CO
Aug 19, 8:13 PM MDT	HEAVY RAIN 6.61	4 Ese Pleasant Valley, CO

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

The nearest sounding before it

Denver, CO (KDNR), launched 12:00Z, 11.2 hours before the alert went out and 118 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 246 J/kg
Mixed-layer CIN: -241 J/kg
Mixed-layer LCL: 927 m above ground
0-6 km bulk shear: 40 kt
0-1 km storm-relative helicity: -59 m²/s²
0-3 km storm-relative helicity: 35 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

Open this sounding in Storm Lab

The text

As transmitted.

680 
WGUS55 KBOU 192309
FFWBOU
COC095-200215-
/O.NEW.KBOU.FF.W.0077.210819T2309Z-210820T0215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Denver CO
509 PM MDT Thu Aug 19 2021

The National Weather Service in Denver has issued a

* Flash Flood Warning for...
  Southeastern Phillips County in northeastern Colorado...

* Until 815 PM MDT.

* At 509 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2.5 inches of 
  rain have fallen. The expected rainfall rate is 2 to 3 inches in 1 
  hour. Additional rainfall amounts of 1 to 2 inches 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, gulches,
           roads, and poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Holyoke and Pleasant Valley.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Move to higher ground now. Act quickly to protect your life.

Excessive runoff from this storm will cause flash flooding of small 
creeks and streams, country roads, farmland along creeks, and other 
low lying areas.

&&

LAT...LON 4044 10205 4044 10220 4044 10236 4059 10235
      4065 10220 4061 10205 4055 10205 4054 10205
      4050 10205 4049 10205 4047 10205

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...2-3 INCHES IN 1 HOUR

$$

Direnzo

2 follow-up statements

104 
WGUS75 KBOU 200012
FFSBOU

Flash Flood Statement
National Weather Service Denver CO
612 PM MDT Thu Aug 19 2021

COC095-200215-
/O.CON.KBOU.FF.W.0077.000000T0000Z-210820T0215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Phillips CO-
612 PM MDT Thu Aug 19 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 815 PM MDT THIS 
EVENING FOR SOUTHEASTERN PHILLIPS COUNTY...

At 612 PM MDT, gauge reports indicated thunderstorms producing heavy 
rain across the warned area. Between 3 and 5 inches of rain have 
fallen. Additional rainfall amounts of 1 to 3 inches are possible in 
the warned area. Flash flooding is ongoing or expected to begin 
shortly.

HAZARD...Life threatening flash flooding. Thunderstorms producing
         flash flooding.

SOURCE...Gauges reported.

IMPACT...Life threatening flash flooding of creeks and streams,
         roads, and low lying areas.

Some locations that will experience flash flooding include...
  Holyoke and Pleasant Valley.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Move to higher ground now. Act quickly to protect your life.

Excessive runoff from this storm will cause flash flooding of small 
creeks and streams, country roads, farmland along creeks, and other 
low lying areas.

&&

LAT...LON 4044 10205 4044 10220 4044 10236 4059 10235
      4065 10220 4061 10205 4055 10205 4054 10205
      4050 10205 4049 10205 4047 10205

FLASH FLOOD...GAUGE INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

Direnzo

058 
WGUS75 KBOU 200058
FFSBOU

Flash Flood Statement
National Weather Service Denver CO
658 PM MDT Thu Aug 19 2021

COC095-200215-
/O.CON.KBOU.FF.W.0077.000000T0000Z-210820T0215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Phillips CO-
658 PM MDT Thu Aug 19 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 815 PM MDT THIS 
EVENING FOR SOUTHEASTERN PHILLIPS COUNTY...

At 658 PM MDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. Between 4 and 6 inches of rain have 
fallen. Flash flooding is ongoing or expected to begin shortly.

HAZARD...Life threatening flash flooding. Thunderstorms producing
         flash flooding.

SOURCE...Radar.

IMPACT...Life threatening flash flooding of creeks and streams,
         roads, and low lying areas.

Some locations that will experience flash flooding include...
  Holyoke and Pleasant Valley.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Move to higher ground now. Act quickly to protect your life.

Excessive runoff from this storm will cause flash flooding of small 
creeks and streams, country roads, farmland along creeks, and other 
low lying areas.

&&

LAT...LON 4044 10205 4044 10220 4044 10236 4059 10235
      4065 10220 4061 10205 4055 10205 4054 10205
      4050 10205 4049 10205 4047 10205

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

Direnzo

The office that day

Everything else NWS Denver/Boulder, CO issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 19, 1:23 PM MDT	Special Weather Statement	BOU	Logan	22 min
Aug 19, 2:01 PM MDT	Special Weather Statement	BOU	Logan	29 min
Aug 19, 2:13 PM MDT	Special Weather Statement	BOU	Broomfield	17 min
Aug 19, 2:17 PM MDT	Special Weather Statement	BOU	Broomfield	28 min
Aug 19, 2:24 PM MDT	Severe Thunderstorm Warning Considerable damage threat	BOU	Boulder, Broomfield, Jefferson	36 min
Aug 19, 2:30 PM MDT	Severe Thunderstorm Warning	BOU	Douglas	30 min
Aug 19, 2:39 PM MDT	Tornado Warning	BOU	Adams, Broomfield, Jefferson	36 min
Aug 19, 2:46 PM MDT	Severe Thunderstorm Warning	BOU	Adams, Weld	29 min
Aug 19, 2:59 PM MDT	Areal Flood Advisory	BOU	Adams	61 min
Aug 19, 3:05 PM MDT	Tornado Warning	BOU	Adams, Weld	25 min
Aug 19, 3:12 PM MDT	Tornado Warning	BOU	Douglas	18 min
Aug 19, 3:14 PM MDT	Severe Thunderstorm Warning	BOU	Weld	31 min
Aug 19, 3:35 PM MDT	Severe Thunderstorm Warning	BOU	Douglas, Elbert	25 min
Aug 19, 3:42 PM MDT	Severe Thunderstorm Warning Considerable damage threat	BOU	Weld	33 min
Aug 19, 3:44 PM MDT	Severe Thunderstorm Warning	BOU	Adams, Arapahoe	31 min
Aug 19, 3:46 PM MDT	Tornado Warning	BOU	Douglas, Elbert	14 min
Aug 19, 3:49 PM MDT	Severe Thunderstorm Warning	BOU	Phillips	41 min
Aug 19, 3:51 PM MDT	Severe Thunderstorm Warning	BOU	Sedgwick	24 min
Aug 19, 3:55 PM MDT	Areal Flood Advisory	BOU	Arapahoe, Denver, Douglas	22 min
Aug 19, 3:58 PM MDT	Areal Flood Advisory	BOU	Weld	30 min
Aug 19, 4:04 PM MDT	Severe Thunderstorm Warning	BOU	Arapahoe, Elbert	41 min
Aug 19, 4:06 PM MDT	Areal Flood Advisory	BOU	Logan	54 min
Aug 19, 4:07 PM MDT	Severe Thunderstorm Warning Considerable damage threat	BOU	Morgan	32 min
Aug 19, 4:10 PM MDT	Areal Flood Advisory	BOU	Phillips	95 min
Aug 19, 4:17 PM MDT	Severe Thunderstorm Warning	BOU	Adams	43 min
Aug 19, 4:18 PM MDT	Severe Thunderstorm Warning	BOU	Elbert	42 min
Aug 19, 4:25 PM MDT	Severe Thunderstorm Warning Considerable damage threat	BOU	Phillips	35 min
Aug 19, 4:32 PM MDT	Severe Thunderstorm Warning Considerable damage threat	BOU	Arapahoe	28 min
Aug 19, 4:34 PM MDT	Tornado Warning	BOU	Phillips	26 min
Aug 19, 4:52 PM MDT	Severe Thunderstorm Warning Considerable damage threat	BOU	Arapahoe, Elbert	23 min
Aug 19, 4:57 PM MDT	Areal Flood Advisory	BOU	Logan	50 min
Aug 19, 4:57 PM MDT	Tornado Warning	BOU	Phillips	33 min
Aug 19, 5:00 PM MDT	Severe Thunderstorm Warning	BOU	Adams, Morgan	30 min
Aug 19, 5:04 PM MDT	Severe Thunderstorm Warning	BOU	Logan	25 min
Aug 19, 5:34 PM MDT	Severe Thunderstorm Warning	BOU	Phillips	26 min

Nearby

Flash Flood Warnings in Colorado, 2021 Every 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.