Alert archive / Utah / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 21, NWS Grand Junction, CO

August 18, 2021Grand County, San Juan County, Utah

NWS Grand Junction, CO issued this severe thunderstorm warning at Aug 18, 2021, 4:36 PM MDT for Grand County, San Juan County, Utah. It was in force for 24 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Aug 18, 2021, 4:36 PM MDT (22:36 UTC)
Expired: Aug 18, 2021, 5:00 PM MDT
In force: 24 min
Issued by: NWS Grand Junction, CO
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties Grand County, UT, San Juan County, UT

The radar

The Grand Junction radar (KGJX), 155 km from the middle of the area, began a volume at 22:39 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Aug 18, 12:14 PM MDT	Severe Thunderstorm Watch	SPC	8 hr

The nearest sounding before it

Grand Junction, CO (KGJT), launched 12:00Z, 10.6 hours before the alert went out and 136 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 2642 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 67 m²/s²
0-3 km storm-relative helicity: 197 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

166 
WUUS55 KGJT 182236
SVRGJT
UTC019-037-182300-
/O.NEW.KGJT.SV.W.0021.210818T2236Z-210818T2300Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Grand Junction CO
436 PM MDT Wed Aug 18 2021

The National Weather Service in Grand Junction has issued a

* Severe Thunderstorm Warning for...
  Northern San Juan County in southeastern Utah...
  Southeastern Grand County in east central Utah...

* Until 500 PM MDT.

* At 435 PM MDT, severe thunderstorms were located along a line 
  extending from Thompson Springs to near Canyonlands National Park, 
  moving east at 20 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs, siding, and trees.

* These severe thunderstorms will remain over mainly rural areas of
  northern San Juan and southeastern Grand Counties, including the
  following locations... Arches National Park, Cisco and Dead Horse
  Point State Park.

 This includes the following highways...
 Interstate 70 in Utah between mile markers 183 and 213.
 U.S. Highway 191 in Utah between mile markers 120 and 155.
 Utah 128 between mile markers 0 and 16, and between mile markers 39
and 44.
 Utah 279 between mile markers 0 and 15.
 Utah 313 between mile markers 0 and 22.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 3896 10980 3903 10928 3841 10951 3835 10994
      3836 10995 3835 10995 3834 10998 3837 10998
      3839 10997 3839 10999 3837 11000 3838 11000
TIME...MOT...LOC 2235Z 253DEG 19KT 3892 10963 3839 10981 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

KJS

The office that day

Everything else NWS Grand Junction, CO issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 17, 6:49 PM MDT	Special Weather Statement	GJT	Uintah	26 min
Aug 18, 1:19 PM MDT	Special Weather Statement	GJT	San Juan	26 min
Aug 18, 4:03 PM MDT	Special Weather Statement	GJT	Grand	27 min
Aug 18, 4:57 PM MDT	Severe Thunderstorm Warning	GJT	Grand, San Juan	33 min

Nearby

Severe Thunderstorm Warnings in Utah, 2021 Every severe thunderstorm 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.