Alert archive / Wyoming / Special Weather Statements in 2015

Special Weather Statement, NWS Riverton, WY

August 3, 2015

NWS Riverton, WY issued this special weather statement at Aug 3, 2015, 4:21 PM MDT. 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 3, 2015, 4:21 PM MDT (22:21 UTC)
Expired
Aug 3, 2015, 5:00 PM MDT
In force
39 min
Issued by
NWS Riverton, WY

The radar

The Riverton/Lander radar (KRIW), 194 km from the middle of the area, began a volume at 22:21 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 12:00Z, 10.4 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 12:00Z on 2015-08-03Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2 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, Riverton, WY at 12:00Z on 2015-08-03The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 2 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
2 J/kg
Mixed-layer CIN
-437 J/kg
Mixed-layer LCL
2320 m above ground
0-6 km bulk shear
13 kt
0-1 km storm-relative helicity
2 m²/s²
0-3 km storm-relative helicity
43 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

696 
WWUS85 KRIW 032221
SPSRIW

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RIVERTON WY
421 PM MDT MON AUG 3 2015
 
WYZ011-020-032300-
NATRONA COUNTY LOWER ELEVATIONS-SOUTHEAST JOHNSON COUNTY-
421 PM MDT MON AUG 3 2015

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN NATRONA AND
SOUTHEASTERN JOHNSON COUNTIES UNTIL 500 PM MDT...

AT 419 PM MDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 
SOUTH OF MIDWEST NEAR STATE HIGHWAY 259. THIS STORM WAS MOVING NORTH 
AT 15 MPH. HEAVY RAINFALL OF UP TO ONE INCH IS POSSIBLE OVER A 30 
MINUTE PERIOD...WHICH COULD QUICKLY FILL DITCHES...LOW LYING 
AREAS...DRY WASHES...AND SMALL CREEKS. FREQUENT CLOUD-TO-GROUND 
LIGHTNING AND WIND GUSTS TO 40 MPH ARE ALSO LIKELY.

THIS STRONG THUNDERSTORM WILL BE NEAR MIDWEST AND EDGERTON AROUND 
430 PM MDT. STATE HIGHWAYS 259 AND 387 WILL ALSO BE IMPACTED AND 
MOTORISTS SHOULD BE PREPARED FOR PONDING OF WATER ON THE ROAD AND 
REDUCED VISIBILITY DUE TO THE HEAVY RAIN.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TORRENTIAL RAINFALL IS ALSO OCCURRING WITH THIS STORM...AND MAY LEAD
TO FLASH FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED
ROADWAYS.

FREQUENT CLOUD TO GROUND LIGHTNING IS OCCURRING WITH THIS STORM.
LIGHTNING CAN STRIKE 15 MILES AWAY FROM A THUNDERSTORM. SEEK A SAFE
SHELTER INSIDE A BUILDING OR VEHICLE.

&&

LAT...LON 4349 10608 4325 10608 4326 10636 4359 10638
      4358 10602 4350 10602
TIME...MOT...LOC 2217Z 182DEG 25KT 4334 10623 

$$

MCDONALD

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 3, 12:52 AM MDTFlash Flood WatchRIWFremont, Lincoln, Sublette25 hr
Aug 3, 2:58 PM MDTSpecial Weather StatementRIWNatrona47 min
Aug 3, 3:16 PM MDTSpecial Weather StatementRIWWashakie44 min
Aug 3, 3:49 PM MDTSpecial Weather StatementRIWNatrona41 min
Aug 3, 3:53 PM MDTSpecial Weather StatementRIW22 min
Aug 3, 4:03 PM MDTSpecial Weather StatementRIWWashakie42 min
Aug 3, 4:49 PM MDTSpecial Weather StatementRIWFremont41 min
Aug 3, 5:11 PM MDTSpecial Weather StatementRIWJohnson64 min
Aug 3, 5:31 PM MDTSpecial Weather StatementRIWSweetwater44 min

Nearby

Special Weather Statements in Wyoming, 2015Every special weather statement in 2015

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.