Alert archive / Utah / Flash Flood Warnings in 2017

Flash Flood Warning 7, NWS Salt Lake City, UT

July 18, 2017Iron County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Jul 18, 2017, 1:59 PM MDT for Iron 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 18, 2017, 1:59 PM MDT (19:59 UTC)
Expired
Jul 18, 2017, 5:00 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), 18 km from the middle of the area, began a volume at 20:00 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, 8.0 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-pSkew-T log-p diagram, Las Vegas, NV at 12:00Z on 2017-07-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 750 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Las Vegas, NV at 12:00Z on 2017-07-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -5 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
750 J/kg
Mixed-layer CIN
-232 J/kg
Mixed-layer LCL
2438 m above ground
0-6 km bulk shear
7 kt
0-1 km storm-relative helicity
-5 m²/s²
0-3 km storm-relative helicity
36 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

547 
WGUS55 KSLC 181959
FFWSLC
UTC021-182300-
/O.NEW.KSLC.FF.W.0007.170718T1959Z-170718T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
159 PM MDT TUE JUL 18 2017

The National Weather Service in Salt Lake City has issued a

* Flash Flood Warning for...
  Brian Head Burn Scar in East central Iron County in southern 
  Utah...

* Until 500 PM MDT
    
* At 153 PM MDT, Doppler radar indicated a thunderstorm producing 
  heavy rain over the Brian Head burn scar just north of the town of 
  Brian Head. Up to one inch of rain has already fallen with 
  additional precipitation expected. Flash flooding is 
  imminent.

* Some locations that will experience flooding include...
  State Route 143 north of Brian Head and Parowan. 

Excessive rainfall over the Brian Head burn scar will result in 
debris flow impacting State Route 143 and potentially the community 
of Parowan. The debris flow can consist of rock, mud, vegetation and 
other loose materials.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3769 11279 3769 11288 3784 11283 3784 11280

$$

RG
1 follow-up statement
524 
WGUS75 KSLC 182256
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
456 PM MDT TUE JUL 18 2017

UTC021-182303-
/O.EXP.KSLC.FF.W.0007.000000T0000Z-170718T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Iron UT-
456 PM MDT TUE JUL 18 2017

...THE FLASH FLOOD WARNING FOR EAST CENTRAL IRON COUNTY WILL EXPIRE
AT 500 PM MDT...

The intense rainfall that had fallen over the Brian Head Burn Scar 
produced a small amount of debris over SR 143.  Rainfall has since 
ceased and flash flooding is no longer a threat.



 LAT...LON 3769 11279 3769 11288 3784 11283 3784 11280

$$

mcinerney

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 17, 6:05 PM MDTSevere Thunderstorm WarningSLCSalt Lake, Tooele40 min
Jul 17, 7:28 PM MDTSpecial Weather StatementSLCRich47 min
Jul 17, 8:12 PM MDTFlash Flood WarningSLCIron, Kane, Washington6 hr
Jul 18, 11:38 AM MDTRed Flag WarningSLCBox Elder, Davis, Salt Lake, Tooele, Utah34 hr
Jul 18, 3:09 PM MDTFlash Flood WatchSLC31 hr

Nearby

Flash Flood Warnings in Utah, 2017Every flash flood warning in 2017

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.