Alert archive / Utah / Flash Flood Warnings in 2017

Flash Flood Warning 31, NWS Salt Lake City, UT

July 29, 2017Washington County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Jul 29, 2017, 2:05 PM MDT for Washington County, Utah. It was in force for 4 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 29, 2017, 2:05 PM MDT (20:05 UTC)
Expired
Jul 29, 2017, 6:00 PM MDT
In force
4 hr
Issued by
NWS Salt Lake City, UT
Area
Storm-based polygon
Flood severity
None

County Washington County, UT

The radar

The Cedar City radar (KICX), 31 km from the middle of the area, began a volume at 20:07 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, 8.1 hours before the alert went out and 253 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 2017-07-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 20 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 2017-07-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 69 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
20 J/kg
Mixed-layer CIN
-343 J/kg
Mixed-layer LCL
3022 m above ground
0-6 km bulk shear
7 kt
0-1 km storm-relative helicity
69 m²/s²
0-3 km storm-relative helicity
117 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

535 
WGUS55 KSLC 292005
FFWSLC
UTC053-300000-
/O.NEW.KSLC.FF.W.0031.170729T2005Z-170730T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
205 PM MDT SAT JUL 29 2017

The National Weather Service in Salt Lake City has issued a

* Flash Flood Warning for...
  East central Washington County in northern Utah...

* Until 600 PM MDT
    
* At 202 PM MDT, Doppler radar indicated a thunderstorm producing 
  heavy rain over Zion National Park. This heavy rain is falling in 
  the North Fork of the Virgin River drainage and Orderville 
  Canyon. Flash flooding is expected to begin shortly.

* Some locations that will experience flooding include...
  Zion National Park including the Narrows on the North Fork of the 
  Virgin River. 

LAT...LON 3741 11290 3723 11290 3721 11298 3729 11300
      3738 11300

$$

PW
2 follow-up statements
005 
WGUS75 KSLC 292218
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
418 PM MDT SAT JUL 29 2017

UTC053-300000-
/O.CON.KSLC.FF.W.0031.000000T0000Z-170730T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Washington UT-
418 PM MDT SAT JUL 29 2017

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 600 PM MDT FOR
EAST CENTRAL WASHINGTON COUNTY...

At 414 PM MDT, thunderstorms have ended across the park but the 
heavy runoff from these storms is likely moving down the Virgin 
River towards the narrows. Flash flooding is still expected along 
the Virgin River through the rest of this afternoon. 

Some locations that will experience flooding include...
Zion National Park.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 3741 11290 3723 11290 3721 11298 3729 11300
      3738 11300

$$

PW
354 
WGUS75 KSLC 292356
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
556 PM MDT SAT JUL 29 2017

UTC053-300004-
/O.EXP.KSLC.FF.W.0031.000000T0000Z-170730T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Washington UT-
556 PM MDT SAT JUL 29 2017

...THE FLASH FLOOD WARNING FOR EAST CENTRAL WASHINGTON COUNTY WILL
EXPIRE AT 600 PM MDT...

The heavy rain has ended in this area, however flooding is still 
possible along the Virgin River as the runoff from the earlier rain 
travels downstream. Please continue to use caution along the 
Virgin River through this evening. 

LAT...LON 3741 11290 3723 11290 3721 11298 3729 11300
      3738 11300

$$

PW

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 28, 6:07 PM MDTFlash Flood WarningSLCKane6 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.