Alert archive / Colorado / Flash Flood Warnings in 2021
Flash Flood Warning 78, NWS Denver/Boulder, CO
NWS Denver/Boulder, CO issued this flash flood warning at Aug 19, 2021, 7:43 PM MDT for Phillips County, Colorado. It was in force for 3 hr. 12 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, 7:43 PM MDT (01:43 UTC)
- Expired
- Aug 19, 2021, 10:45 PM MDT
- In force
- 3 hr
- Issued by
- NWS Denver/Boulder, CO
- Area
- Storm-based polygon
- Damage threat
- Considerable
- Flood severity
- None
County Phillips County, CO
The radar
The Goodland radar (KGLD), 135 km from the middle of the area, began a volume at 01:47 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, 7:52 PM MDT | HEAVY RAIN 2.48 | 1 Ne Amherst, CO | |
| Aug 19, 7:53 PM MDT | HEAVY RAIN 2 | 2 N Amherst, CO | |
| 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 | |
| Aug 19, 8:27 PM MDT | FLASH FLOOD | 7 Ssw Pleasant Valley, CO | WIDESPREAD FLOODING OF ROADS, DITCHES, AND FIELDS. AT LEAST ONE ROAD CROSSING FRENCHMAN CREEK ARE IMPASSABLE. FRENCHMAN CREEK AND OTHER STREAMS HAVE SIGNIFICANT FLOODING. |
| Aug 19, 8:36 PM MDT | HEAVY RAIN 3.94 | 3 Sw Holyoke, CO | |
| Aug 19, 8:40 PM MDT | FLASH FLOOD | 8 Sse Pleasant Valley, CO | THREE 6 INCH RAIN GAUGES ON HIS FARM OVERFLOWED. |
| Aug 19, 8:44 PM MDT | HEAVY RAIN 7 | 4 Ese Pleasant Valley, CO | |
| Aug 19, 8:54 PM MDT | HEAVY RAIN 7.5 | 7 Se Holyoke, 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 00:00Z, 1.7 hours before the alert went out and 108 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.
- Mixed-layer CAPE
- 56 J/kg
- Mixed-layer CIN
- -210 J/kg
- Mixed-layer LCL
- 1497 m above ground
- 0-6 km bulk shear
- 52 kt
- 0-1 km storm-relative helicity
- 52 m²/s²
- 0-3 km storm-relative helicity
- 222 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- -0.0
The text
As transmitted.
937
WGUS55 KBOU 200143
FFWBOU
COC095-200445-
/O.NEW.KBOU.FF.W.0078.210820T0143Z-210820T0445Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Denver CO
743 PM MDT Thu Aug 19 2021
The National Weather Service in Denver has issued a
* Flash Flood Warning for...
Eastern Phillips County in northeastern Colorado...
* Until 1045 PM MDT.
* At 743 PM MDT, Doppler radar indicated thunderstorms producing
heavy rain across the warned area. Between 3 and 6 inches of rain
have fallen with locally higher amounts. Flash flooding is ongoing
in Holyoke with Main Street flooded. Flooding is likely far worse
southeast of Holyoke where the heaviest rain has fallen.
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, Amherst and Pleasant Valley.
Additional storms continue to move north northeast into the warned
area.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles. do not drive through flooded areas
especially at night since it is difficult to determine flood depths.
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 10245 4060 10240 4069 10227 4075 10205
4044 10205 4044 10209 4044 10218 4044 10222
4044 10225 4044 10234 4044 10242
FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
$$
TH1 follow-up statement
431
WGUS75 KBOU 200257
FFSBOU
Flash Flood Statement
National Weather Service Denver CO
857 PM MDT Thu Aug 19 2021
COC095-200445-
/O.CON.KBOU.FF.W.0078.000000T0000Z-210820T0445Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Phillips CO-
857 PM MDT Thu Aug 19 2021
...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1045 PM MDT THIS
EVENING FOR EASTERN PHILLIPS COUNTY...
At 857 PM MDT, the public reported heavy rain across the warned
area. Between 4 and 8 inches of rain have fallen. Flash flooding is
already occurring.
HAZARD...Life threatening flash flooding. Thunderstorms producing
flash flooding.
SOURCE...Public reported.
IMPACT...Life threatening flash flooding of creeks and streams,
roads, and low lying areas.
Some locations that will experience flash flooding include...
Holyoke, Amherst and Pleasant Valley.
This includes the following streams and drainages...
Sandy Creek, North Fork Frenchman Creek, Frenchman Creek,
Wildhorse Creek and Patent Creek.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
Be especially cautious at night when it is harder to recognize the
dangers of flooding.
Excessive runoff from this storm will cause flash flooding of small
creeks and streams, country roads, farmland along creeks, and other
low lying areas.
&&
LAT...LON 4044 10245 4060 10240 4069 10227 4075 10205
4044 10205 4044 10209 4044 10218 4044 10222
4044 10225 4044 10234 4044 10242
FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
$$
RPKThe office that day
Everything else NWS Denver/Boulder, CO issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 19, 6:21 PM MDT | Severe Thunderstorm Warning | BOU | Phillips | 24 min |
| Aug 19, 6:41 PM MDT | Severe Thunderstorm Warning | BOU | Phillips | 49 min |
| Aug 19, 6:43 PM MDT | Areal Flood Advisory | BOU | Phillips | 2 hr |
| Aug 19, 10:38 PM MDT | Flash Flood Warning | BOU | Phillips | 4 hr |
| Aug 20, 2:12 AM MDT | Areal Flood Advisory | BOU | Larimer | 93 min |
| Aug 20, 2:15 AM MDT | Flash Flood Warning | BOU | Larimer | 2 hr |
| Aug 20, 2:58 AM MDT | Areal Flood Warning | BOU | Phillips | 9 hr |
| Aug 20, 4:01 AM MDT | Special Weather Statement | BOU | Morgan | 44 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.