Alert archive / Utah / Flash Flood Warnings in 2018

Flash Flood Warning 4, NWS Salt Lake City, UT

July 9, 2018Iron County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Jul 9, 2018, 2:36 PM MDT for 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 9, 2018, 2:36 PM MDT (20:36 UTC)
Expired: Jul 9, 2018, 5:30 PM MDT
In force: 3 hr
Issued by: NWS Salt Lake City, UT
Area: Storm-based polygon
Flood severity: None

County Iron County, UT

The radar

The Cedar City radar (KICX), 21 km from the middle of the area, began a volume at 20:38 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 9, 2:44 PM MDT	FLASH FLOOD	4 N Brian Head, UT	STATE ROUTE 143 CLOSED DUE TO WATER AND DEBRIS OVER ROADWAY.
Jul 9, 2:44 PM MDT	FLASH FLOOD	4 N Brian Head, UT	STATE ROUTE 143 CLOSED DUE TO WATER OVER ROADWAY.

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 12:00Z, 8.6 hours before the alert went out and 286 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: 71 J/kg
Mixed-layer CIN: -265 J/kg
Mixed-layer LCL: 3146 m above ground
0-6 km bulk shear: 6 kt
0-1 km storm-relative helicity: -19 m²/s²
0-3 km storm-relative helicity: -1 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

070 
WGUS55 KSLC 092036
FFWSLC
UTC021-092330-
/O.NEW.KSLC.FF.W.0004.180709T2036Z-180709T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
236 PM MDT MON JUL 9 2018

The National Weather Service in Salt Lake City has issued a

* Flash Flood Warning for...
  East central Iron County in southern Utah...

* Until 530 PM MDT

* At 233 PM MDT, it was indicated that portions of SR-143 near the 
  town of Brian Head is impassable due to flood water. Doppler radar 
  indicated that heavy rainfall has been falling over the area and 1 
  inch of rain has fallen over the past hour. 

* Due to proximity to the Brian Head Burn Scar, it is expected that 
  this amount of rainfall may result in flash flooding and a debris 
  flow through the Parowan Creek drainage including Benson, Center, 
  Bowery, and Soda Springs side drainages.
  State Route 143 is expected to receive debris, as well as locations
  along Parowan Creek downstream to the town of Parowan. People in
  this area should take action to ensure their safety!
  

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.

If a debris flow has occurred it is important to realize that the
runout area remains very dangerous. Additional debris flows may occur
within minutes of the original flow. Please remain vigilant and be
prepared to take swift action.

&&

LAT...LON 3770 11287 3784 11287 3786 11282 3786 11279
      3770 11276

$$

NC

2 follow-up statements

239 
WGUS75 KSLC 092205
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
405 PM MDT MON JUL 9 2018

UTC021-092330-
/O.CON.KSLC.FF.W.0004.000000T0000Z-180709T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Iron UT-
405 PM MDT MON JUL 9 2018

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 530 PM MDT FOR
EAST CENTRAL IRON COUNTY...

Media reports indicate that as of 4 PM portions of SR 143 between 
mileposts 12 and 14 remain closed to mud/debris covering the road 
from previous flash flooding. Additional flash flooding and debris 
flow from the Brian Head burn scar is possible in the Parowan Creek 
drainage including Benson, Center, Bowery, and Soda Springs side 
drainages. State Route 143 could receive debris, as well as 
locations along Parowan Creek downstream to the town of Parowan. 
People in this area should take action to ensure their safety!

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.

If a debris flow has occurred it is important to realize that the
runout area remains very dangerous. Additional debris flows may occur
within minutes of the original flow. Please remain vigilant and be
prepared to take swift action.

&&

LAT...LON 3770 11287 3784 11287 3786 11282 3786 11279
      3770 11276

$$

NC

683 
WGUS75 KSLC 092334
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
534 PM MDT MON JUL 9 2018

UTC021-092343-
/O.EXP.KSLC.FF.W.0004.000000T0000Z-180709T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Iron UT-
534 PM MDT MON JUL 9 2018

...THE FLASH FLOOD WARNING FOR EAST CENTRAL IRON COUNTY HAS
EXPIRED...

The heavy rain has ended. Flooding is no longer expected to pose a
threat. Please continue to heed any remaining road closures.

LAT...LON 3770 11287 3784 11287 3786 11282 3786 11279
      3770 11276

$$

NC

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 8, 6:48 PM MDT	Special Weather Statement	SLC	Salt Lake	42 min
Jul 9, 3:28 PM MDT	Special Weather Statement	SLC	Wasatch	47 min
Jul 9, 3:35 PM MDT	Special Weather Statement	SLC	Utah	40 min
Jul 9, 4:12 PM MDT	Special Weather Statement	SLC	Summit	48 min
Jul 9, 5:07 PM MDT	Special Weather Statement	SLC	Morgan	38 min

Nearby

Flash Flood Warnings in Utah, 2018 Every flash flood warning in 2018

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.