Alert archive / Utah / Flash Flood Warnings in 2021

Flash Flood Warning 70, NWS Salt Lake City, UT

July 30, 2021Washington County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Jul 30, 2021, 2:17 PM MDT for Washington County, Utah. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Jul 30, 2021, 2:17 PM MDT (20:17 UTC)
Expired: Jul 30, 2021, 5:15 PM MDT
In force: 3 hr
Issued by: NWS Salt Lake City, UT
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

County Washington County, UT

The radar

The Cedar City radar (KICX), 39 km from the middle of the area, began a volume at 20:18 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.

The nearest sounding before it

Las Vegas, NV (KVEF), launched 12:00Z, 8.3 hours before the alert went out and 248 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: 17 J/kg
Mixed-layer CIN: -233 J/kg
Mixed-layer LCL: 2114 m above ground
0-6 km bulk shear: 6 kt
0-1 km storm-relative helicity: 14 m²/s²
0-3 km storm-relative helicity: -15 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

187 
WGUS55 KSLC 302017
FFWSLC
UTC053-302315-
/O.NEW.KSLC.FF.W.0070.210730T2017Z-210730T2315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
217 PM MDT Fri Jul 30 2021

The National Weather Service in Salt Lake City has issued a

* Flash Flood Warning for...
  Eastern Washington County in southwestern Utah...

* Until 515 PM MDT.

* At 217 PM MDT, Rangers at Zion National Park reported flash 
  flooding from heavy rain beginning in Spry Canyon, Clear Creek, 
  and Telephone Canyon. Doppler radar estimates that between 0.25 
  and 0.5 inches of rain have already fallen. Flash flooding is 
  ongoing or expected to begin shortly.

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

  SOURCE...Trained spotters reported.

  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, including Clear Creek, Spry Canyon, and 
  Telephone Canyon.

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 3720 11299 3730 11302 3730 11301 3731 11293
      3721 11290

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

MT

1 follow-up statement

660 
WGUS75 KSLC 302312
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
512 PM MDT Fri Jul 30 2021

UTC053-302322-
/O.EXP.KSLC.FF.W.0070.000000T0000Z-210730T2315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Washington UT-
512 PM MDT Fri Jul 30 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 515 PM MDT THIS AFTERNOON FOR 
EASTERN WASHINGTON COUNTY...

Flooding is no longer expected to pose a threat. Please continue to 
heed remaining road closures.

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

LAT...LON 3720 11299 3730 11302 3730 11301 3731 11293
      3721 11290

$$

MT

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 29, 6:03 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Garfield	117 min
Jul 29, 6:03 PM MDT	Special Weather Statement	SLC	Kane	27 min
Jul 29, 6:24 PM MDT	Special Weather Statement	SLC	Kane	36 min
Jul 29, 7:06 PM MDT	Special Weather Statement	SLC	Washington	24 min
Jul 29, 7:16 PM MDT	Special Weather Statement	SLC	Wayne	29 min
Jul 29, 7:23 PM MDT	Special Weather Statement	SLC	Wayne	37 min
Jul 29, 7:40 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Kane	3 hr
Jul 29, 7:41 PM MDT	Severe Thunderstorm Warning	SLC	Garfield, Wayne	34 min
Jul 29, 7:46 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Kane	3 hr
Jul 29, 7:52 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Garfield, Wayne	113 min
Jul 29, 8:11 PM MDT	Special Weather Statement	SLC	Iron	19 min
Jul 29, 8:51 PM MDT	Special Weather Statement	SLC	Iron	39 min
Jul 29, 9:01 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Washington	3 hr
Jul 29, 9:42 PM MDT	Special Weather Statement	SLC	Carbon	63 min
Jul 30, 3:38 AM MDT	Flash Flood Watch	SLC	Beaver, Garfield, Iron, Kane, Piute, Washington and 1 more	19 hr
Jul 30, 2:18 PM MDT	Special Weather Statement	SLC	Sevier	42 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.