Alert archive / Wyoming / Special Weather Statements in 2017
Special Weather Statement, NWS Riverton, WY
NWS Riverton, WY issued this special weather statement at Jul 20, 2017, 9:31 PM MDT for Sweetwater County, Wyoming. It was in force for 29 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
- Jul 20, 2017, 9:31 PM MDT (03:31 UTC)
- Expired
- Jul 20, 2017, 10:00 PM MDT
- In force
- 29 min
- Issued by
- NWS Riverton, WY
County Sweetwater County, WY
The radar
The Riverton/Lander radar (KRIW), 159 km from the middle of the area, began a volume at 03:32 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 00:00Z, 3.5 hours before the alert went out and 302 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.
- Mixed-layer CAPE
- 783 J/kg
- Mixed-layer CIN
- -21 J/kg
- Mixed-layer LCL
- 2771 m above ground
- 0-6 km bulk shear
- 15 kt
- 0-1 km storm-relative helicity
- 26 m²/s²
- 0-3 km storm-relative helicity
- 107 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
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</html>What forecasters said that day
The local office's own words before this special weather statement went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Riverton, WY wrote its last area forecast discussion before this special weather statement went out at Jul 20, 2:56 PM MDT, 6 hours 35 minutes earlier.
Area forecast discussion, Jul 20, 2:56 PM MDT, 6 hours 35 minutes before
Area Forecast Discussion National Weather Service Riverton WY 256 PM MDT Thu Jul 20 2017 .SHORT TERM...(This evening through Friday) Issued at 234 PM MDT Thu Jul 20 2017 This evening is shaping up to be one of the more active windows of opportunity for active weather this week. A well defined shortwave will be making landfall onto the Pacific Coast today along with a lead vorticity lobe tracking east across the area. With PBS of around n inch stream in from the southwest with the monsoon moisture and instability in place, it appears we have a good shot of thunderstorm activity during the next 24 hours. the timing of this feature will result in the majority of this activity to fire up after 00z this evening. However, there is already convective activity with sold lightning just to the west close to the Idaho/Montana border. This activity will move east and become rejuvenated from afternoon heating resulting in a fairly active period for the remainder of this afternoon in our western zones. then this convection will spread to areas east of the divide after 00z this evening. As it does, this band of convection will encounter increasing speed and directional shear as the storm cells approach Natrona and Johnson Counties where we have a slight risk of severe for strong winds and large hail. it appears that johnson county stands the best chance of any severe activity this evening along with a Urn shear factor of 93 by 03Z this evening. Then as high pressure builds in from the west, we can look forward to a dry weekend, Temperatures will start out relatively cooler, with the biggest cool down expected in Johnson county Friday. There should be some lingering shower activity in the Casper area Friday morning and dissipating just after 12z. Otherwise, the only other activity expected Friday will be some lingering monsoon moisture and instability for the southern tier zones to experience some sold to widely sct convective activity Friday afternoon. Saturday and Sunday will be dry with a warming trend with highs back up in the low to mid 90s in the central basins and 80s in the western valleys. .LONG TERM...(Friday night through Thursday) Issued at 234 PM MDT Thu Jul 20 2017 Monday will be the hottest day of the week with high temperatures flirting with the century mark in the Big Horn basin. Then the temperatures will slowly cool off during the rest of the week through Thursday as the "ring of fire" consisting of monsoon moisture laden wet thunderstorms rides up and over the large bubble of high pressure over the Western United States Tuesday and Wednesday, along with increasing clouds and wet thunderstorm activity, thus cooling the daytime high temps. The models are in better agreement with the overall trend then they were yesterday keeping the high over us with weak disturbances rounding the ridge. && .AVIATION...(For the 18Z TAFS through 18Z Friday afternoon) Issued at 234 PM MDT Thu Jul 20 2017 Expect mainly VFR conditions to continue through the forecast period. Kept in the mention of VCTS/SHRA for most locations through the majority of the forecast period until close to 06Z Friday. KCPR and KBYG stand the best chance of lowered vsbys and cigs as well as any small hail from thunderstorms this afternoon. Another round of isolated to widely scattered thunderstorms is expected across southern Sweetwater County Friday afternoon. KRKS may get grazed by these storms. && .FIRE WEATHER... Issued AT 234 PM MDT Thu Jul 20 2017 Monsoonal moisture and a passing cold front will move through the area and bring an increased chance of showers and thunderstorms. These storms have a better chance of bring wet with a chance of hail and erratic winds as well. Relative humidity should remain somewhat higher than recent days as well. For the most part, wind should remain light to moderate outside of any shower or thunderstorm. Mixing and smoke dispersal will generally range from good to very good but fair in some of the Basins. Another round of isolated to widely scattered thunderstorms is expected across southern Sweetwater County Friday afternoon. KRKS may get grazed by these storms. && .RIW WATCHES/WARNINGS/ADVISORIES... NONE. && SHORT TERM...Lipson LONG TERM...Lipson AVIATION...Lipson FIRE WEATHER...Lipson
Hazardous weather outlook, Jul 20, 2:21 AM MDT, 19 hours 10 minutes before
Hazardous Weather Outlook National Weather Service Riverton WY 221 AM MDT Thu Jul 20 2017 WYZ001>020-022>030-211100- Yellowstone National Park-Absaroka Mountains-Cody Foothills- North Big Horn Basin-Southwest Big Horn Basin- Southeast Big Horn Basin-Owl Creek and Bridger Mountains- Bighorn Mountains West-Bighorn Mountains Southeast- Northeast Johnson County-Southeast Johnson County- Teton and Gros Ventre Mountains-Jackson Hole- Wind River Mountains West-Wind River Mountains East- Upper Wind River Basin-Wind River Basin-Lander Foothills- Green Mountains and Rattlesnake Range- Natrona County Lower Elevations-Casper Mountain-Star Valley- Salt River and Wyoming Ranges-Upper Green River Basin Foothills- Upper Green River Basin-South Lincoln County- Rock Springs and Green River-Flaming Gorge-East Sweetwater County- 221 AM MDT Thu Jul 20 2017 This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight Isolated to widely scattered afternoon and evening thunderstorms. Heavy rain, hail and strong gusty wind are possible with any storm. The best chance of strong storms will be in Natrona and Johnson Counties. .DAYS TWO THROUGH SEVEN...Friday through Wednesday Friday...Isolated thunderstorms across the south. Monday through Wednesday...Isolated to scattered afternoon and evening thunderstorms. .SPOTTER INFORMATION STATEMENT... Spotters are urged to report wind gusts over 45 mph, hail and any flooding. Thank you.
In the hours before
Special weather statement, Jul 20, 5:15 PM MDT, 4 hours 16 minutes before
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</html>Special weather statement, Jul 20, 5:57 PM MDT, 3 hours 34 minutes before
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</html>Special weather statement, Jul 20, 8:07 PM MDT, 1 hour 24 minutes before
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</html>Special weather statement, Jul 20, 9:31 PM MDT, 0 minutes before
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</html>The office that day
Everything else NWS Riverton, WY issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 20, 6:47 PM MDT | Special Weather Statement | RIW | Natrona | 43 min |
| Jul 20, 7:34 PM MDT | Special Weather Statement | RIW | Natrona | 26 min |
| Jul 20, 8:07 PM MDT | Special Weather Statement | RIW | 38 min | |
| Jul 21, 5:21 AM MDT | Special Weather Statement | RIW | Sublette | 39 min |
| Jul 21, 6:30 AM MDT | Special Weather Statement | RIW | 30 min | |
| Jul 21, 8:03 AM MDT | Special Weather Statement | RIW | 42 min | |
| Jul 21, 8:13 AM MDT | Special Weather Statement | RIW | 47 min | |
| Jul 21, 9:01 AM MDT | Special Weather Statement | RIW | 29 min | |
| Jul 21, 9:37 AM MDT | Special Weather Statement | RIW | 38 min | |
| Jul 21, 10:20 AM MDT | Special Weather Statement | RIW | 40 min | |
| Jul 21, 10:57 AM MDT | Special Weather Statement | RIW | 48 min | |
| Jul 21, 11:36 AM MDT | Special Weather Statement | RIW | 24 min | |
| Jul 21, 12:04 PM MDT | Special Weather Statement | RIW | 56 min | |
| Jul 21, 1:00 PM MDT | Special Weather Statement | RIW | 30 min | |
| Jul 21, 1:28 PM MDT | Special Weather Statement | RIW | 47 min | |
| Jul 21, 2:23 PM MDT | Special Weather Statement | RIW | 52 min | |
| Jul 21, 2:40 PM MDT | Severe Thunderstorm Warning | RIW | Sweetwater | 35 min |
| Jul 21, 3:02 PM MDT | Severe Thunderstorm Warning | RIW | Sweetwater | 16 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.