Alert archive / Wyoming / Special Weather Statements in 2017

Special Weather Statement, NWS Riverton, WY

August 1, 2017Johnson County, Wyoming

NWS Riverton, WY issued this special weather statement at Aug 1, 2017, 6:21 PM MDT for Johnson County, Wyoming. It was in force for 39 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 1, 2017, 6:21 PM MDT (00:21 UTC)
Expired
Aug 1, 2017, 7:00 PM MDT
In force
39 min
Issued by
NWS Riverton, WY

County Johnson County, WY

The radar

The Riverton/Lander radar (KRIW), 191 km from the middle of the area, began a volume at 00:21 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

Riverton, WY (KRIW), launched 00:00Z, 0.4 hours before the alert went out and 187 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, Riverton, WY at 00:00Z on 2017-08-02Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 342 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, Riverton, WY at 00:00Z on 2017-08-02The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 163 square meters per square second.193958Sfc1 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
342 J/kg
Mixed-layer CIN
-110 J/kg
Mixed-layer LCL
3526 m above ground
0-6 km bulk shear
40 kt
0-1 km storm-relative helicity
163 m²/s²
0-3 km storm-relative helicity
287 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.4

Open this sounding in Storm Lab

The text

As transmitted.

011 
WWUS85 KRIW 020021
SPSRIW

Special Weather Statement
National Weather Service Riverton WY
621 PM MDT TUE AUG 1 2017
 
WYZ009>011-020100-
Southeast Johnson County-Bighorn Mountains Southeast-Northeast
Johnson County-
621 PM MDT TUE AUG 1 2017

...SPECIAL WEATHER STATEMENT...

At 618 PM MDT, Doppler radar was tracking a strong thunderstorm near
Saddlestring, which is 12 miles west of Buffalo, moving southeast at
25 mph.

Half inch hail and winds in excess of 30 mph will be possible with 
this storm. Occasional cloud to ground lightning and locally heavy 
rainfall is also expected with this storm. 

This strong thunderstorm will be near...
  Buffalo around 650 PM MDT. 

Other locations impacted by this storm include Buffalo Golf Course, 
Middle Fork Campground, Johnson County Fairgrounds, Tie Hack 
Campground, Indian Campground. 

This includes the following highways...
 Interstate 25 between mile markers 285 and 299.
 Interstate 90 between mile markers 60 and 70.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Occasional cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 4441 10705 4448 10699 4428 10646 4406 10676
TIME...MOT...LOC 0018Z 315DEG 20KT 4440 10696 

$$

Lipson

The office that day

Everything else NWS Riverton, WY issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 1, 6:33 PM MDTSevere Thunderstorm WarningRIWJohnson20 min
Aug 1, 6:57 PM MDTSpecial Weather StatementRIWJohnson33 min

Nearby

Special Weather Statements in Wyoming, 2017Every special weather statement 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.