Alert archive / Utah / Flash Flood Warnings in 2021
Flash Flood Warning 117, NWS Salt Lake City, UT
NWS Salt Lake City, UT issued this flash flood warning at Aug 18, 2021, 9:39 PM MDT for Iron County, Washington County, Utah. It was in force for 3 hr. 2 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 18, 2021, 9:39 PM MDT (03:39 UTC)
- Expired
- Aug 19, 2021, 12:45 AM MDT
- In force
- 3 hr
- Issued by
- NWS Salt Lake City, UT
- Area
- Storm-based polygon
- Damage threat
- Considerable
- Flood severity
- None
Counties Iron County, UT, Washington County, UT
The radar
The Cedar City radar (KICX), 30 km from the middle of the area, began a volume at 03:41 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 18, 11:30 PM MDT | FLASH FLOOD | Kanarraville, UT | IRON COUNTY EMERGENCY MANAGER REPORTED AN OLD DIKE COLLAPSED DUE TO HEAVY RAINFALL WITH A LARGE AMOUNT OF DEBRIS ACROSS OLD US 91 CLOSING THE ROAD. |
| Aug 19, 12:00 AM MDT | FLASH FLOOD | 9 Ese New Harmony, UT | ZION NATIONAL PARK REPORTED KOLOB CANYONS SECTION OF THE PARK WAS CLOSED DUE TO A LARGE AMOUNT OF MUD AND ROCK SLIDES FROM OVERNIGHT FLASH FLOODING. EXACT TIME OF FLOODING UNKNOW DUE TO OVERNIGHT TIMING, BUT ESTIMATED FROM RADAR. |
Local storm reports filed while the alert was in force, from inside its polygon or its counties.
The nearest sounding before it
Las Vegas, NV (KVEF), launched 00:00Z, 3.7 hours before the alert went out and 243 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 3543 m above ground
- 0-6 km bulk shear
- 23 kt
- 0-1 km storm-relative helicity
- 11 m²/s²
- 0-3 km storm-relative helicity
- 14 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
053
WGUS55 KSLC 190339
FFWSLC
UTC021-053-190645-
/O.NEW.KSLC.FF.W.0117.210819T0339Z-210819T0645Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
939 PM MDT Wed Aug 18 2021
The National Weather Service in Salt Lake City has issued a
* Flash Flood Warning for...
Southern Iron County in southern Utah...
Northeastern Washington County in southwestern Utah...
* Until 1245 AM MDT.
* At 939 PM MDT, Doppler radar indicated thunderstorms producing
heavy rain across the warned area. Between 0.75 and 1 inch of rain
has fallen. Additional rainfall amounts of 0.75 to 1.5 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...Radar.
IMPACT...Life threatening flash flooding of creeks and streams,
urban areas, highways, streets and underpasses.
* Some locations that will experience flash flooding include...
Kolob Canyon and La Verkin Creek section of Zion National Park,
New Harmony, Kanarraville, and Pintura.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
&&
LAT...LON 3753 11328 3761 11313 3761 11312 3763 11298
3754 11294 3735 11308 3731 11322 3730 11335
3740 11340
FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
$$
MPS2 follow-up statements
405
WGUS75 KSLC 190526
FFSSLC
Flash Flood Statement
National Weather Service Salt Lake City UT
1126 PM MDT Wed Aug 18 2021
UTC021-053-190645-
/O.CON.KSLC.FF.W.0117.000000T0000Z-210819T0645Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Iron UT-Washington UT-
1126 PM MDT Wed Aug 18 2021
...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1245 AM MDT THURSDAY
FOR SOUTHERN IRON AND NORTHEASTERN WASHINGTON COUNTIES...
At 1126 PM MDT, Doppler radar indicated thunderstorms producing
heavy rain across the warned area. Between 1 and 2 inches of rain
have fallen. Additional rainfall amounts of 0.25 to 0.5 inches are
possible in the warned area. Flash flooding is ongoing or expected
to begin shortly.
HAZARD...Life threatening flash flooding. Thunderstorms producing
flash flooding.
SOURCE...Radar.
IMPACT...Life threatening flash flooding of creeks and streams,
urban areas, highways, streets and underpasses.
Some locations that will experience flash flooding include...
Kolob Canyon and La Verkin Creek section of Zion National Park,
New Harmony, Kanarraville, and Pintura.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
&&
LAT...LON 3753 11328 3761 11313 3761 11312 3763 11298
3754 11294 3735 11308 3731 11322 3730 11335
3740 11340
FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
$$
MPS411
WGUS75 KSLC 190647
FFSSLC
Flash Flood Statement
National Weather Service Salt Lake City UT
1247 AM MDT Thu Aug 19 2021
UTC021-053-190657-
/O.EXP.KSLC.FF.W.0117.000000T0000Z-210819T0645Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Iron UT-Washington UT-
1247 AM MDT Thu Aug 19 2021
...FLASH FLOOD WARNING HAS EXPIRED FOR SOUTHERN IRON AND
NORTHEASTERN WASHINGTON COUNTIES...
The heavy rain has ended across southern Iron and northeastern
Washington Counties. Flooding is no longer expected to pose an
immediate threat. Runoff from earlier heavy rain will continue to
gradually decrease, although light to occasionally moderate rain
will continue through late tonight. Please continue to heed any
remaining road closures.
A Flash Flood Watch remains in effect until 600 AM MDT for portions
of central Utah, northern Utah and southern Utah.
A Flash Flood Watch remains in effect until 600 AM MDT for a portion
of southwest Utah.
LAT...LON 3753 11328 3761 11313 3761 11312 3763 11298
3754 11294 3735 11308 3731 11322 3730 11335
3740 11340
$$
LCThe office that day
Everything else NWS Salt Lake City, UT issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 18, 7:43 PM MDT | Flash Flood Warning | SLC | Kane | 4 hr |
| Aug 18, 8:01 PM MDT | Flash Flood Warning | SLC | Garfield | 3 hr |
| Aug 18, 8:46 PM MDT | Special Weather Statement | SLC | Iron | 44 min |
| Aug 18, 9:48 PM MDT | Areal Flood Advisory | SLC | Iron | 5 min |
| Aug 18, 9:53 PM MDT | Flash Flood Warning | SLC | Iron | 3 hr |
| Aug 18, 10:07 PM MDT | Flash Flood Warning | SLC | Iron | 3 hr |
| Aug 18, 11:11 PM MDT | Flash Flood Warning | SLC | Kane, Washington | 5 hr |
| Aug 19, 1:43 AM MDT | Flash Flood Warning | SLC | Garfield, Wayne | 3 hr |
| Aug 19, 2:03 AM MDT | Flash Flood Warning | SLC | Garfield, Kane, San Juan | 6 hr |
| Aug 19, 2:31 AM MDT | Flash Flood Warning | SLC | Kane | 3 hr |
| Aug 19, 3:50 AM MDT | Special Weather Statement | SLC | 25 min | |
| Aug 19, 9:39 AM MDT | Special Weather Statement | SLC | Kane | 36 min |
| Aug 19, 10:16 AM MDT | River Flood Warning | SLC | Duchesne | 4 hr |
| Aug 19, 10:54 AM MDT | Special Weather Statement | SLC | Juab | 51 min |
| Aug 19, 11:15 AM MDT | Areal Flood Advisory | SLC | Millard | 2 hr |
| Aug 19, 11:42 AM MDT | Special Weather Statement | SLC | Sanpete | 48 min |
| Aug 19, 12:29 PM MDT | Special Weather Statement | SLC | Sanpete | 46 min |
| Aug 19, 12:49 PM MDT | Flash Flood Warning | SLC | Garfield, Wayne | 3 hr |
| Aug 19, 1:04 PM MDT | Special Weather Statement | SLC | Utah | 56 min |
| Aug 19, 1:25 PM MDT | Special Weather Statement | SLC | Carbon | 50 min |
| Aug 19, 2:12 PM MDT | Special Weather Statement | SLC | Carbon, Duchesne | 63 min |
| Aug 19, 2:59 PM MDT | Special Weather Statement | SLC | Duchesne | 61 min |
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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.