Alert archive / Utah / Flash Flood Warnings in 2021
Flash Flood Warning 76, NWS Salt Lake City, UT
NWS Salt Lake City, UT issued this flash flood warning at Jul 31, 2021, 5:39 PM MDT for Kane County, Washington County, Utah. It was in force for 5 hr. 3 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
- Jul 31, 2021, 5:39 PM MDT (23:39 UTC)
- Expired
- Jul 31, 2021, 10:45 PM MDT
- In force
- 5 hr
- Issued by
- NWS Salt Lake City, UT
- Area
- Storm-based polygon
- Damage threat
- Considerable
- Flood severity
- None
Counties Kane County, UT, Washington County, UT
The radar
The Cedar City radar (KICX), 40 km from the middle of the area, began a volume at 23:38 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 |
|---|---|---|---|
| Jul 31, 6:15 PM MDT | FLASH FLOOD | Zion Np, UT | ZIOIN NP DISPATCH REPORTS ALL SLOT CANYONS IN ZION NP ARE EXPERIENCING FLOODING PINE CREEK AND SPRY CANYON IN PARTICULAR. THE ZION RAWS REPORTED 1.29 INCHES OF RAIN IN ONE HOUR. STILL RAINING AT OBSERVATION TIME. |
| Jul 31, 6:30 PM MDT | FLASH FLOOD | 3 Se Springdale, UT | STREAM GAUGE ON THE EAST FORK OF THE VIRGIN RIVER RECORDED A PEAK FLOW OF 2790 CFS. |
| Jul 31, 7:15 PM MDT | FLASH FLOOD | 3 Ssw Zion Np, UT | USGS STREAM GAUGE RECORDED FLOWS OF 2400 CFS ON THE NORTH FORK OF THE VIRGIN RIVER NEAR SPRINGDALE. |
Local storm reports filed while the alert was in force, from inside its polygon or its counties.
The nearest sounding before it
Flgstf/Belemont, AZ (KFGZ), launched 12:00Z, 11.7 hours before the alert went out and 244 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
- 319 J/kg
- Mixed-layer CIN
- -38 J/kg
- Mixed-layer LCL
- 865 m above ground
- 0-6 km bulk shear
- 4 kt
- 0-1 km storm-relative helicity
- 29 m²/s²
- 0-3 km storm-relative helicity
- -25 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
443
WGUS55 KSLC 312339
FFWSLC
UTC025-053-010245-
/O.NEW.KSLC.FF.W.0076.210731T2339Z-210801T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
539 PM MDT Sat Jul 31 2021
The National Weather Service in Salt Lake City has issued a
* Flash Flood Warning for...
West Central Kane County in southern Utah...
East Central Washington County in southwestern Utah...
* Until 845 PM MDT.
* At 539 PM MDT, Doppler radar indicated thunderstorms producing
intense rainfall moving into Zion National Park from the east
southeast. The expected rainfall rate is 1 to 3 inches in 1 hour.
Flash flooding is expected to begin shortly, with rainfall moving
into the East Fork of the Virgin River region now, and shortly
into Pine Creek, Keyhole, and Spry slot canyons over the next few
minutes.
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...
Zion National Park and Springdale.
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.
Flooding is occurring or is imminent. It is important to know where
you are relative to streams, rivers, or creeks which can become
killers in heavy rains. Campers and hikers should avoid streams or
creeks.
&&
LAT...LON 3713 11301 3744 11300 3741 11281 3719 11279
3711 11282
FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
EXPECTED RAINFALL...1-3 INCHES IN 1 HOUR
$$
GM5 follow-up statements
104
WGUS75 KSLC 312358
FFSSLC
Flash Flood Statement
National Weather Service Salt Lake City UT
558 PM MDT Sat Jul 31 2021
UTC025-053-010245-
/O.CON.KSLC.FF.W.0076.000000T0000Z-210801T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kane UT-Washington UT-
558 PM MDT Sat Jul 31 2021
...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 845 PM MDT THIS
EVENING FOR WEST CENTRAL KANE AND EAST CENTRAL WASHINGTON COUNTIES...
At 558 PM MDT, Thunderstorms producing intense rain have overspread
the eastern half of Zion National Park. Between 0.4 and 1 inch of
rain has fallen over the last 20 minutes and amounts are climbing
fast. The expected rainfall rate is between 1 to 3 inches in 1 hour.
Flash flooding is ongoing or expected to begin shortly.
HAZARD...Life threatening flash flooding. Thunderstorms producing
flash flooding.
SOURCE...Radar.
IMPACT...Life threatening flash flooding of all slot canyons
surrounding Zion Canyon initially, then the North Fork
of the Virgin River.
Some locations that will experience flash flooding include...
Zion National Park and Springdale.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
Be aware of your surroundings and do not drive on flooded roads.
Flooding is occurring or is imminent. It is important to know where
you are relative to streams, rivers, or creeks which can become
killers in heavy rains. Campers and hikers should avoid streams or
creeks.
&&
LAT...LON 3713 11301 3744 11300 3741 11281 3719 11279
3711 11282
FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
EXPECTED RAINFALL...1-3 INCHES IN 1 HOUR
$$
GM333
WGUS75 KSLC 010043
FFSSLC
Flash Flood Statement
National Weather Service Salt Lake City UT
643 PM MDT Sat Jul 31 2021
UTC025-053-010245-
/O.CON.KSLC.FF.W.0076.000000T0000Z-210801T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kane UT-Washington UT-
643 PM MDT Sat Jul 31 2021
...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 845 PM MDT THIS
EVENING FOR WEST CENTRAL KANE AND EAST CENTRAL WASHINGTON COUNTIES...
At 643 PM MDT, Zion National Park Dispatch has reported that slot
canyons within and adjacent to Zion National Park, including Spry
Canyon, are currently flashing. Debris has crossed roadways within
the park in some locations. Between 0.5 and 1.5 inches of rain have
fallen. Flash flooding is already occurring.
HAZARD...Life threatening flash flooding. Thunderstorms producing
flash flooding.
SOURCE...Zion National Park Dispatch.
IMPACT...Life threatening flash flooding of slot canyons, creeks
and streams
Some locations that will experience flash flooding include...
Zion National Park and Springdale.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
Flooding is occurring. It is important to know where you are
relative to streams, rivers, or creeks which can become killers in
heavy rains. Campers and hikers should avoid streams or creeks and
move to higher ground immediately.
&&
LAT...LON 3713 11301 3744 11300 3741 11281 3719 11279
3711 11282
FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
$$
GM788
WGUS75 KSLC 010118
FFSSLC
Flash Flood Statement
National Weather Service Salt Lake City UT
718 PM MDT Sat Jul 31 2021
UTC025-053-010245-
/O.CON.KSLC.FF.W.0076.000000T0000Z-210801T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kane UT-Washington UT-
718 PM MDT Sat Jul 31 2021
...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 845 PM MDT THIS
EVENING FOR WEST CENTRAL KANE AND EAST CENTRAL WASHINGTON COUNTIES...
At 718 PM MDT, In addition to flash flooding of slot canyons within
Zion Canyon, gauge reports from the North Fork of the Virgin River
have risen from 60 cubic feet per second (cfs) to 1570 cfs over the
last hour. River levels are continuing to rise. Flash flooding is
already occurring.
HAZARD...Life threatening flash flooding from earlier
thunderstorms
SOURCE...Zion National Park Dispatch and USGS River Gauges.
IMPACT...Life threatening flash flooding of slot canyons, creeks,
and streams.
Some locations that will experience flash flooding include...
Zion National Park and Springdale.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
Flooding is occurring or is imminent. It is important to know where
you are relative to streams, rivers, or creeks which can become
killers in heavy rains. Campers and hikers should avoid streams or
creeks.
&&
LAT...LON 3713 11301 3744 11300 3741 11281 3719 11279
3711 11282
FLASH FLOOD...GAUGE INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
$$
GM019
WGUS55 KSLC 010234
FFWSLC
UTC025-053-010445-
/O.EXT.KSLC.FF.W.0076.000000T0000Z-210801T0445Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
834 PM MDT Sat Jul 31 2021
The National Weather Service in Salt Lake City has extended the
* Flash Flood Warning for...
West Central Kane County in southern Utah...
East Central Washington County in southwestern Utah...
* Until 1045 PM MDT.
* At 834 PM MDT, USGS gauge reports show declining flows along the
North Fork of the Virgin River after a peak of just over 2400
cubic feet per second (cfs), but flows remain elevated at 1280 cfs
currently. Flash flooding continues, but will gradually improve
over the next several hours.
HAZARD...Life threatening flash flooding along the North Fork
of the Virgin River and its tributaries.
SOURCE...Zion National Park Dispatch and USGS River gauges.
IMPACT...Life threatening flash flooding of slot canyons,
creeks and streams.
* Some locations that will experience flash flooding include...
The North Fork of the Virgin River within Zion National Park.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
Flooding is occurring. It is important to know where you are
relative to streams, rivers, or creeks which can become killers in
heavy rains. Campers and hikers should avoid streams or creeks and
remain at higher ground if trapped.
&&
LAT...LON 3713 11301 3744 11300 3741 11281 3719 11279
3711 11282
FLASH FLOOD...GAUGE INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
$$
GM384
WGUS75 KSLC 010440
FFSSLC
Flash Flood Statement
National Weather Service Salt Lake City UT
1040 PM MDT Sat Jul 31 2021
UTC025-053-010450-
/O.EXP.KSLC.FF.W.0076.000000T0000Z-210801T0445Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kane UT-Washington UT-
1040 PM MDT Sat Jul 31 2021
...FLASH FLOOD WARNING WILL EXPIRE AT 1045 PM MDT THIS EVENING FOR
WEST CENTRAL KANE AND EAST CENTRAL WASHINGTON COUNTIES...
The heavy rain has ended and flood waters will gradually decrease
through the overnight hours. Peak flows were observed to be nearly
2400 CFS at the USGS stream gauge on the North Fork of the Virgin
River, but are beginning to decrease. Runoff from the earlier heavy
rainfall will continue downstream to the confluence with the Virgin
River. Flooding is not anticipated to pose any imminent threat,
however, waters will likely remain high through the overnight hours.
Please continue to heed any road closures.
LAT...LON 3713 11301 3744 11300 3741 11281 3719 11279
3711 11282
$$
SWThe office that day
Everything else NWS Salt Lake City, UT issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 30, 7:17 PM MDT | Special Weather Statement | SLC | Beaver | 43 min |
| Jul 30, 7:31 PM MDT | Special Weather Statement | SLC | 44 min | |
| Jul 31, 12:31 PM MDT | Special Weather Statement | SLC | Summit | 44 min |
| Jul 31, 1:12 PM MDT | Special Weather Statement | SLC | Iron | 33 min |
| Jul 31, 1:23 PM MDT | Flash Flood Warning | SLC | Duchesne, Wasatch | 3 hr |
| Jul 31, 1:30 PM MDT | Severe Thunderstorm Warning | SLC | Iron, Washington | 30 min |
| Jul 31, 1:39 PM MDT | Special Weather Statement | SLC | Morgan | 36 min |
| Jul 31, 2:10 PM MDT | Special Weather Statement | SLC | Morgan | 50 min |
| Jul 31, 2:38 PM MDT | Special Weather Statement | SLC | Morgan | 37 min |
| Jul 31, 2:47 PM MDT | Severe Thunderstorm Warning | SLC | Morgan, Rich, Summit | 28 min |
| Jul 31, 2:52 PM MDT | Special Weather Statement | SLC | Rich | 23 min |
| Jul 31, 3:00 PM MDT | Areal Flood Advisory | SLC | Iron | 107 min |
| Jul 31, 3:10 PM MDT | Special Weather Statement | SLC | Morgan | 20 min |
| Jul 31, 3:16 PM MDT | Severe Thunderstorm Warning | SLC | Box Elder, Cache, Weber | 29 min |
| Jul 31, 3:35 PM MDT | Flash Flood Warning | SLC | Iron | 3 hr |
| Jul 31, 3:41 PM MDT | Special Weather Statement | SLC | Cache | 19 min |
| Jul 31, 4:00 PM MDT | Severe Thunderstorm Warning | SLC | Iron | 30 min |
| Jul 31, 4:06 PM MDT | Special Weather Statement | SLC | Beaver | 24 min |
| Jul 31, 4:10 PM MDT | Flash Flood Warning | SLC | Utah | 3 hr |
| Jul 31, 4:19 PM MDT | Flash Flood Warning | SLC | Duchesne | 3 hr |
| Jul 31, 4:39 PM MDT | Special Weather Statement | SLC | Rich | 66 min |
| Jul 31, 5:01 PM MDT | Special Weather Statement | SLC | 29 min | |
| Jul 31, 5:11 PM MDT | Flash Flood Warning | SLC | Washington | 3 hr |
| Jul 31, 5:25 PM MDT | Special Weather Statement | SLC | Juab | 35 min |
| Jul 31, 5:37 PM MDT | Special Weather Statement | SLC | Washington | 38 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.