Alert archive / Utah / Flash Flood Warnings in 2021

Flash Flood Warning 62, NWS Salt Lake City, UT

July 28, 2021Morgan County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Jul 28, 2021, 1:55 PM MDT for Morgan 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 28, 2021, 1:55 PM MDT (19:55 UTC)
Expired
Jul 28, 2021, 4:45 PM MDT
In force
3 hr
Issued by
NWS Salt Lake City, UT
Area
Storm-based polygon
Flood severity
None

County Morgan County, UT

The radar

The Salt Lake City radar (KMTX), 87 km from the middle of the area, began a volume at 19:57 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

Salt Lake City I, UT (KSLC), launched 12:00Z, 7.9 hours before the alert went out and 64 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, Salt Lake City I, UT at 12:00Z on 2021-07-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 104 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, Salt Lake City I, UT at 12:00Z on 2021-07-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 67 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
104 J/kg
Mixed-layer CIN
-191 J/kg
Mixed-layer LCL
2082 m above ground
0-6 km bulk shear
12 kt
0-1 km storm-relative helicity
67 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.

666 
WGUS55 KSLC 281955
FFWSLC
UTC029-282245-
/O.NEW.KSLC.FF.W.0062.210728T1955Z-210728T2245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
155 PM MDT Wed Jul 28 2021

The National Weather Service in Salt Lake City has issued a

* Flash Flood Warning for...
  Northeastern Morgan County in northern Utah...

* Until 445 PM MDT.

* At 155 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across headwaters of the Lost Creek watershed. Between 
  2 and 3.25 inches of rain have fallen within the last hour. Flash 
  flooding is ongoing or expected to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  mainly rural areas of Northeastern Morgan County

This includes the following streams and drainages...
  Lost Creek through the intersection with North Lost Creek Road.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4129 11142 4129 11141 4128 11137 4126 11133
      4121 11136 4120 11137 4115 11139 4111 11147
      4112 11150 4124 11148 4125 11145

FLASH FLOOD...RADAR INDICATED

$$

SW
1 follow-up statement
069 
WGUS75 KSLC 282249
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
449 PM MDT Wed Jul 28 2021

UTC029-282259-
/O.EXP.KSLC.FF.W.0062.000000T0000Z-210728T2245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Morgan UT-
449 PM MDT Wed Jul 28 2021

...FLASH FLOOD WARNING HAS EXPIRED FOR NORTHEASTERN MORGAN COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. runoff from earlier heavy rainfall will continue to decrease 
through the evening hours. Please continue to heed any road closures.

LAT...LON 4129 11142 4129 11141 4128 11137 4126 11133
      4121 11136 4120 11137 4115 11139 4111 11147
      4112 11150 4124 11148 4125 11145

$$

SW

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 28, 11:57 AM MDTSpecial Weather StatementSLCCache48 min
Jul 28, 12:19 PM MDTFlash Flood WarningSLCCache3 hr
Jul 28, 2:17 PM MDTFlash Flood Warning Considerable damage threatSLCEmery3 hr
Jul 28, 3:47 PM MDTFlash Flood WarningSLCDavis, Morgan3 hr
Jul 28, 3:50 PM MDTSevere Thunderstorm WarningSLCBox Elder25 min

Nearby

Flash Flood Warnings in Utah, 2021Every 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.