Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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420 FXUS65 KRIW 110352 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 952 PM MDT Mon Jun 10 2024 .KEY MESSAGES... - Isolated showers and thunderstorms, some on the strong side, will continue through late afternoon. Strong outflow winds and isolated large hail is possible with this activity, as well as brief heavy rain. - Warmer and drier conditions expected Tuesday through much of the week. - Elevated river levels will continue this week. && .DISCUSSION... Issued at 153 PM MDT Mon Jun 10 2024 A strong shortwave visible on water vapor is currently pushing east across northern Wyoming. This will be the impetus for convection today, focused east of the Divide. An associated cold front will drop south through the afternoon, shunting the deeper moisture that was over the area yesterday farther to the east. There are a few showers already ongoing across the Bighorn Basin late this morning, and additional development is expected farther south and east over the next couple of hours. The most favorable environment will be across Johnson and Natrona counties where the better moisture will be. With peak heating, instability will increase with MLCAPE values of 500-1000+ J/kg and lapse rate of 7-8 C/km across these areas. Given the well-mixed boundary layer, strong, gusty outflow winds are the main concern, as well as isolated large hail with the stronger storms. With PWAT values around three quarters to an inch, brief, heavy rain is also possible. This activity will quickly move out by late afternoon as the wave pushes farther east. Tuesday will mark the beginning of a drier period as brief ridging sets up across the region. Temperatures will peak 7 to 10 degrees above average. Humidity will drop to below 20 percent across much of central and southern Wyoming; with a breezy west wind, elevated fire weather conditions will return for the afternoon. By Wednesday a fairly zonal flow will take over, keeping active weather away from the area. Temperatures will rise further, likely peaking in the low to mid 90s for lower elevations east of the Divide. It will be another windy day, meaning another day of elevated to near- critical fire weather conditions. By Thursday flow will become slightly more southwesterly, likely helping to return isolated convection over the mountains. Guidance diverges somewhat on Friday; the general trend is for increased cyclonic flow with a better chance for more widespread convection. Ensemble cluster guidance is still favoring troughing to increase during the weekend. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 952 PM MDT Mon Jun 10 2024 Conditions will remain VFR and mostly SKC through the TAF period. A northwesterly to northeasterly breeze will continue at several terminals this evening into tonight. Wind will increase at KRKS late Tuesday morning and at other terminals in the afternoon. Gusts will range from 20-25 knots (slightly higher at KRKS) once wind increases. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on 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...Myers AVIATION...Rowe HYDROLOGY...LaVoie