Alert archive / Utah / Flash Flood Warnings in 2021

Flash Flood Warning 12, NWS Salt Lake City, UT

July 15, 2021Beaver County, Iron County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Jul 15, 2021, 8:39 PM MDT for Beaver County, Iron 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: Jul 15, 2021, 8:39 PM MDT (02:39 UTC)
Expired: Jul 15, 2021, 11:45 PM MDT
In force: 3 hr
Issued by: NWS Salt Lake City, UT
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

Counties Beaver County, UT, Iron County, UT

The radar

The Cedar City radar (KICX), 79 km from the middle of the area, began a volume at 02:40 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 15, 10:10 PM MDT	FLASH FLOOD	Lund, UT	* 3 INJ * TRAIN DERAILMENT REPORTED DUE TO HIGH WATER FROM FLASH FLOODING.14 TRAIN CARS WERE DERAILED. EMERGENCY RESPONDER VEHICLE WAS OVERTAKEN BY WATER ON THE WAY TO THE SITE.
Jul 15, 10:10 PM MDT	FLASH FLOOD	Lund, UT	* 3 INJ * TRAIN DERAILMENT REPORTED DUE TO HIGH WATER FROM FLASH FLOODING. 95 TRAIN CARS WERE DERAILED.

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, 2.7 hours before the alert went out and 264 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: 688 J/kg
Mixed-layer CIN: -18 J/kg
Mixed-layer LCL: 3158 m above ground
0-6 km bulk shear: 12 kt
0-1 km storm-relative helicity: 9 m²/s²
0-3 km storm-relative helicity: 16 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

278 
WGUS55 KSLC 160239
FFWSLC
UTC001-021-160545-
/O.NEW.KSLC.FF.W.0012.210716T0239Z-210716T0545Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
839 PM MDT Thu Jul 15 2021

The National Weather Service in Salt Lake City has issued a

* Flash Flood Warning for...
  Southwestern Beaver County in southern Utah...
  Northwestern Iron County in southern Utah...

* Until 1145 PM MDT.

* At 839 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 3 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,
           urban areas, highways, streets and underpasses.

* Some locations that will experience flash flooding include...
  Lund.

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.

&&

LAT...LON 3814 11375 3822 11341 3823 11320 3814 11318
      3803 11327 3790 11359 3798 11376

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

$$

Church

2 follow-up statements

113 
WGUS75 KSLC 160359
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
959 PM MDT Thu Jul 15 2021

UTC001-021-160545-
/O.CON.KSLC.FF.W.0012.000000T0000Z-210716T0545Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Beaver UT-Iron UT-
959 PM MDT Thu Jul 15 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1145 PM MDT THIS 
EVENING FOR SOUTHWESTERN BEAVER AND NORTHWESTERN IRON COUNTIES...

At 959 PM MDT, Doppler radar and automated rain gauges indicated 
thunderstorms producing heavy rain across the warned area. Between 3 
and 7 inches of rain have fallen across portions of the warned area 
northwest of Lund. Jensen Spring reported 1.18" of rain in an hour 
on the periphery of the heaviest rainfall. Flash flooding is ongoing 
or expected to begin shortly.

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

SOURCE...Radar and automated gauges.

IMPACT...Life threatening flash flooding of creeks and streams,
         urban areas, highways, streets and underpasses.

Some locations that will experience flash flooding include...
  Lund.

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.

&&

LAT...LON 3814 11375 3822 11341 3823 11320 3814 11318
      3803 11327 3790 11359 3798 11376

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

$$

CRK

338 
WGUS75 KSLC 160538
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
1138 PM MDT Thu Jul 15 2021

UTC001-021-160548-
/O.EXP.KSLC.FF.W.0012.000000T0000Z-210716T0545Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Beaver UT-Iron UT-
1138 PM MDT Thu Jul 15 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 1145 PM MDT THIS EVENING FOR 
SOUTHWESTERN BEAVER AND NORTHWESTERN IRON COUNTIES...

The heavy rain has ended.  Additional light rainfall may continue 
across the area through 2 AM MDT.  Streams and washes may continue 
to have elevated flows through the overnight hours.

A Flash Flood Watch remains in effect until 1200 AM MDT for portions 
of southern Utah and southwest Utah.

LAT...LON 3814 11375 3822 11341 3823 11320 3814 11318
      3803 11327 3790 11359 3798 11376

$$

CRK

The office that day

Everything else NWS Salt Lake City, UT issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 15, 6:35 PM MDT	Special Weather Statement	SLC	Salt Lake	40 min
Jul 15, 7:08 PM MDT	Severe Thunderstorm Warning	SLC	Iron	52 min
Jul 16, 12:39 AM MDT	Flash Flood Warning Considerable damage threat	SLC	Kane, Washington	3 hr
Jul 16, 1:05 AM MDT	Flash Flood Warning Considerable damage threat	SLC	Kane, Washington	3 hr
Jul 16, 1:09 AM MDT	Areal Flood Advisory	SLC	Washington	3 hr
Jul 16, 1:07 PM MDT	Special Weather Statement	SLC	Kane	38 min
Jul 16, 1:27 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Kane	3 hr
Jul 16, 1:58 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Garfield, Kane	3 hr
Jul 16, 3:20 PM MDT	Special Weather Statement	SLC		40 min
Jul 16, 3:47 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Garfield, Kane	3 hr
Jul 16, 4:46 PM MDT	Special Weather Statement	SLC	Millard	44 min
Jul 16, 5:04 PM MDT	Severe Thunderstorm Warning	SLC	Millard	56 min

Nearby

Flash Flood Warnings in Utah, 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.