Alert archive / Utah / Flash Flood Warnings in 2021

Flash Flood Warning 127, NWS Salt Lake City, UT

September 1, 2021Kane County, Washington County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Sep 1, 2021, 8:21 AM MDT for Kane County, Washington County, Utah. It was in force for 3 hr. 1 report 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: Sep 1, 2021, 8:21 AM MDT (14:21 UTC)
Expired: Sep 1, 2021, 11:30 AM MDT
In force: 3 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), 36 km from the middle of the area, began a volume at 14:27 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
Sep 1, 8:21 AM MDT	FLASH FLOOD	Zion Np, UT	ZION NATIONAL PARK RANGERS REPORTED FLASH FLOOIDING ACROSS SLOT CANYONS BETWEEN TEMPLE OF THE SUN AND TWINS.

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, 2.4 hours before the alert went out and 249 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 611 m above ground
0-6 km bulk shear: 42 kt
0-1 km storm-relative helicity: 35 m²/s²
0-3 km storm-relative helicity: 48 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

143 
WGUS55 KSLC 011421
FFWSLC
UTC025-053-011730-
/O.NEW.KSLC.FF.W.0127.210901T1421Z-210901T1730Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
821 AM MDT Wed Sep 1 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 1130 AM MDT.

* At 821 AM MDT, Zion National Park rangers indicated flash flooding 
  across slot canyons between Temple of the Sun and the Twins. Flash 
  flooding is ongoing. Additionally, rises on the North Fork of the 
  Virgin River are expected through late morning.

  HAZARD...Life threatening flash flooding. Prolonged moderate to
           heavy rainfall 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.

&&

LAT...LON 3720 11295 3720 11301 3737 11302 3738 11290
      3738 11287 3720 11285

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

$$

SW

2 follow-up statements

797 
WGUS75 KSLC 011608
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
1008 AM MDT Wed Sep 1 2021

UTC025-053-011730-
/O.CON.KSLC.FF.W.0127.000000T0000Z-210901T1730Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kane UT-Washington UT-
1008 AM MDT Wed Sep 1 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1130 AM MDT THIS 
MORNING FOR WEST CENTRAL KANE AND EAST CENTRAL WASHINGTON COUNTIES...

At 1008 AM MDT, Zion National Park rangers indicated flash flooding 
across slot canyons between Temple of the Sun and the Twins. Flash 
flooding is ongoing. Additionally, rises on the North Fork of the 
Virgin River are expected through late morning.

HAZARD...Life threatening flash flooding. Prolonged moderate to
         heavy rainfall 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.

&&

LAT...LON 3720 11295 3720 11301 3737 11302 3738 11290
      3738 11287 3720 11285

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

$$

SW

433 
WGUS75 KSLC 011725
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
1125 AM MDT Wed Sep 1 2021

UTC025-053-011735-
/O.EXP.KSLC.FF.W.0127.000000T0000Z-210901T1730Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kane UT-Washington UT-
1125 AM MDT Wed Sep 1 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 1130 AM MDT THIS MORNING FOR 
WEST CENTRAL KANE AND EAST CENTRAL WASHINGTON COUNTIES...

Flash flooding within some of the slot canyon areas in Zion Canyon 
has ended. Flooding is no longer expected to pose a threat. However, 
modest rises to flows are expected to continue along the North Fork 
of the Virgin River through this afternoon, tapering during the 
evening hours. Please continue to heed any closures in place.

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

LAT...LON 3720 11295 3720 11301 3737 11302 3738 11290
      3738 11287 3720 11285

$$

SW

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 31, 6:17 PM MDT	Special Weather Statement	SLC	Tooele	43 min
Aug 31, 7:22 PM MDT	Special Weather Statement	SLC	Davis	38 min
Sep 1, 1:37 AM MDT	Areal Flood Advisory	SLC	Washington	3 hr
Sep 1, 3:25 PM MDT	Special Weather Statement	SLC	Iron	35 min
Sep 1, 4:59 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Garfield, Wayne	2 hr

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.