Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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958 FXUS65 KRIW 101740 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 1140 AM MDT Mon Jun 10 2024 .KEY MESSAGES... - Isolated showers will remain possible this morning, with the focus shifting to Johnson/Natrona counties this afternoon. A strong to severe storm cannot be ruled out in this area. - Warmer and drier conditions expected Tuesday and Wednesday, with a chance for showers and thunderstorms returning Thursday and Friday. Elevated river and stream levels will continue. && .DISCUSSION... Issued at 212 AM MDT Mon Jun 10 2024 Showers are beginning to end this morning (0130 am) as they move toward the northeast. Thunderstorms have weakened and transitioned to an area of showers over the Bighorn Basin. These showers are expected to end in the next few hours. The cause for this overnight convection is the shortwave trough that has been discussed the last couple of days. It is currently over western MT, trailing over eastern ID. This feature will continue to progress eastward through the morning. As it does so, isolated showers will be possible again over western portions of the CWA after sunrise. The abundant moisture that was in place Sunday will linger today, however sfc winds will turn more northwesterly through the day as a result of the trough and associated cold front. These features will push the Gulf moisture that was in place over Johnson and Natrona counties further east over far eastern WY and western SD/NE. As a result, the severe threat from thunderstorms this afternoon will be confined along the front as it pushes southward over Johnson County into northern Natrona County. Thunderstorms will also be possible over southern portions of Sweetwater County, but are not expected to be strong, let alone severe. Any other showers and/or thunderstorms across the CWA will be very isolated (10%) this afternoon. Otherwise, temperatures will be slightly cooler over the forecast area today and 4 to 8 degrees cooler over western portions. Additionally, gusty west-northwest winds will be widespread across the forecast area, due to the resulting pressure gradient from the passing trough. Dry conditions will return Tuesday, as a transitory ridge moves over the region. A more zonal flow pattern will be in place Wednesday, but this will not stop temperatures from rising into the 90s across areas east of the Divide. A strong high center over AZ/NM will rebuild and push its ridge axis over the Northern Rockies Thursday into Friday. Showers and thunderstorms could return to the area during this time, as an upper level low from the Desert Southwest surges northward. A longwave trough will build over the PACNW and western Canada over the weekend, resulting in southwest flow aloft over the Cowboy State. This could bring elevated fire weather conditions to much of the CWA. && .AVIATION /18Z TAFS THROUGH 18Z TUESDAY/... Issued at 1140 AM MDT Mon Jun 10 2024 A cold front associated with a shortwave trough will pass through the region today, and will bring a line of potentially strong thunderstorms with it. KWRL and KCPR have the best chances of seeing any impacts from this line of storms and thus have included a TEMPO group to cover the most likely timing of those storms. Expect locally heavy rain, gusty winds, and possibly small hail if a storm passes directly over the terminal and brief MVFR conditions are possible. Otherwise, VFR conditions are expected at all terminals through the period. Breezy west to northwest winds at several terminals will decrease between 00Z and 03Z and will be mostly light through the rest of the period. Behind the line of storms, mostly SKC conditions and light winds are expected through the rest of the period. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on smoke, icing, and turbulence forecasts. && .HYDROLOGY... Issued at 212 AM MDT Mon Jun 10 2024 Rivers and creeks will continue to run high today at Action Stage or below, but look to remain steady for now. SnoTel sites above 9000 ft continue to drop with most sites dropping below 5 inches of SWE. The remaining snow at these sites will likely be gone in the next day or so. The notable exception is sites in the Tetons and portions of Yellowstone NP, where 20-30 inches remain on the ground. && .RIW WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...LaVoie AVIATION...Hensley HYDROLOGY...LaVoie