Alert archive / Utah / Flash Flood Warnings in 2017

Flash Flood Warning 30, NWS Salt Lake City, UT

July 28, 2017Kane County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Jul 28, 2017, 6:07 PM MDT for Kane County, Utah. It was in force for 6 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 28, 2017, 6:07 PM MDT (00:07 UTC)
Expired
Jul 29, 2017, 12:00 AM MDT
In force
6 hr
Issued by
NWS Salt Lake City, UT
Area
Storm-based polygon
Flood severity
None

County Kane County, UT

The radar

The Cedar City radar (KICX), 60 km from the middle of the area, began a volume at 00:08 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

Flgstf/Belemont, AZ (KFGZ), launched 00:00Z, 0.1 hours before the alert went out and 229 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, Flgstf/Belemont, AZ at 00:00Z on 2017-07-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 238 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Flgstf/Belemont, AZ at 00:00Z on 2017-07-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -49 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
238 J/kg
Mixed-layer CIN
-56 J/kg
Mixed-layer LCL
1363 m above ground
0-6 km bulk shear
15 kt
0-1 km storm-relative helicity
-49 m²/s²
0-3 km storm-relative helicity
-22 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

925 
WGUS55 KSLC 290007
FFWSLC
UTC025-290300-
/O.NEW.KSLC.FF.W.0030.170729T0007Z-170729T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
607 PM MDT FRI JUL 28 2017

The National Weather Service in Salt Lake City has issued a

* Flash Flood Warning for...
  Southwestern Kane County in southern Utah...

* Until 900 PM MDT
    
* At 602 PM MDT, Doppler radar indicated a thunderstorm producing 
  heavy rain over Johnson Canyon to the east of the town of Kanab. 
  Flash flooding is expected to begin shortly.

* Radar rainfall amounts indicate an average of 1.5 inches of 
  precipitation in a short period of time has fallen over the 
  headwaters of the canyon. Birch, Mineral, Lick Canyons are 
  included in the warning and are part of Johnson Canyon headwaters.

* Please stay away from this area through the evening and night time 
  hours.

LAT...LON 3725 11231 3700 11238 3713 11242 3742 11241
      3740 11225

$$

MCINERNEY
3 follow-up statements
113 
WGUS75 KSLC 290157
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
757 PM MDT FRI JUL 28 2017

UTC025-290300-
/O.CON.KSLC.FF.W.0030.000000T0000Z-170729T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kane UT-
757 PM MDT FRI JUL 28 2017

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 900 PM MDT FOR
SOUTHWESTERN KANE COUNTY...

At 753 PM MDT, Radar rainfall rates indicate that Johnson Canyon 
received an average of 1.5 inches of precipitation over most of the 
headwater area.  As such, it is inferred that flash flooding is 
taking place across a wide range of the canyon.

Currently thunderstorm activity has slowed over the area, but it 
will take until later this evening and into the night time hours for 
the flood to attenuate.

If you are traveling through the canyon this evening please be aware 
of the danger.

LAT...LON 3725 11231 3700 11238 3713 11242 3742 11241
      3740 11225

$$

MCINERNEY
340 
WGUS55 KSLC 290258
FFWSLC
UTC025-290600-
/O.EXT.KSLC.FF.W.0030.000000T0000Z-170729T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
858 PM MDT FRI JUL 28 2017

The National Weather Service in Salt Lake City has extended the

* Flash Flood Warning for...
  Southwestern Kane County in southern Utah...

* Until midnight MDT
    
* At 854 PM MDT, Flash flooding continues through the Johnson Wash 
  Drainage.  Observations have come in indicating that this is a 
  very large and dangerous flood.  If you are in or planning on 
  traveling through Johnson Canyon this evening and through the 
  night, please avoid any low lying areas.

* Earlier rainfall amounts indicated that the upper drainage 
  received up to 2+ inches of rainfall.  This amount has produced 
  flash flooding.

* As a result of the magnitude of the flood, the initial warning was 
  extended to allow the large volume of water to move through the 
  system.

* If you can, avoid this canyon through the evening and night time 
  hours.  If you are in Johnson Canyon be aware of the danger and 
  take actions to ensure for your safety.

LAT...LON 3725 11231 3700 11238 3713 11242 3742 11241
      3740 11225

$$

MCINERNEY
653 
WGUS75 KSLC 290433
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
1033 PM MDT FRI JUL 28 2017

UTC025-290600-
/O.CON.KSLC.FF.W.0030.000000T0000Z-170729T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kane UT-
1033 PM MDT FRI JUL 28 2017

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL MIDNIGHT MDT FOR
SOUTHWESTERN KANE COUNTY...

At 1025 PM MDT, a large and dangerous flash flood had been reported 
in the Johnson Wash drainage due to earlier heavy rain. Flood waters 
will continue to make their way through this drainage through late 
tonight. If you can, avoid this canyon through late tonight. If you 
are in Johnson Canyon, be aware of the danger and take actions to 
ensure our safety.

LAT...LON 3725 11231 3700 11238 3713 11242 3742 11241
      3740 11225

$$

LC

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 29, 2:05 PM MDTFlash Flood WarningSLCWashington4 hr
Jul 29, 2:35 PM MDTFlash Flood WarningSLCKane6 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.