590 FXUS65 KRIW 060430 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 1030 PM MDT Fri Jun 5 2026 .KEY MESSAGES... - Elevated to critical fire weather through the weekend, with gusty winds (25 to 45 mph) and low humidity (7-12%). - Very hot Saturday, with highs in the low to mid-80s west of the Divide and mid 90s to near 100 degrees east of the Divide. - Scattered showers and storms Sunday, mainly north and west. - The overall trend next week looks to be windy, with temperatures closer to seasonal (70s to low-80s). There are also chances for showers and thunderstorms beginning Tuesday. && .UPDATE... Issued at 1240 PM MDT Fri Jun 5 2026 Looking at current satellite imagery, you'd be hard-pressed to find a cloud over the area as dry southwest flow persists. Though a few clouds will develop through the afternoon, the area remains dry today, with high temperatures still forecasted in the 80s to low 90s. The main weather story for today is elevated to near- critical fire weather, as widespread gusty winds of 20 to 35 mph occur, in conjunction with humidity values around and less than 10 percent. && .DISCUSSION... Issued at 224 AM MDT Fri Jun 5 2026 The trough that has been lingering in the vicinity the past couple days is finally moving to the east, which will open the door for the next system to impact the NW Rockies. This system is just starting to drop down the West Coast, and will gradually buckle a ridge ahead of it across the Rockies during the next 48 hours. Today will start with flat ridging, with nearly clear skies and temperatures in the 70s and 80s. West winds will be lighter than yesterday, but a few gusts near 20 mph are possible across the usual areas of central WY. The ridge then starts to build in the vicinity tonight into Saturday, with increasing temperatures aloft. Still noting H7 temps of 16 to 19C, which translates to mid to upper 80s west of the Divide and into the 90s to the east. There remains an outside chance of triple digit readings, mainly on the open ranges of Johnson County and the lowest elevations of the Bighorn Basin. The placement of the ridge is centered on the Central Plains, so a weak impulse may nudge into the NW WY Parks during the afternoon, bringing some cloud cover and a shower or two, and will hold temps there down in the 70s. Saturday will also see increasing southwest winds ahead of the next system. Widespread gusts of 30 to 40 mph are expected across the state. This southwest flow will also be modified desert air, so humidity levels will be falling to 5 to 10 percent across a wide swath of the state. These will result in a near-critical fire weather day across the state. The ridge shifts to the east Saturday night, shifting the moisture tap from the southwest across a larger part of western WY. The first piece of the western trough races across the state, bringing a good chance for showers and thunderstorms. The southwest flow will continue into the middle of next week, which is setting up as a pattern where daytime heating sparks showers and thunderstorms along the highest terrain in the afternoon, dissipating each evening. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 1029 PM MDT Fri Jun 5 2026 VFR conditions will be in place through the TAF period. Clouds will increase from the west-southwest, with SCT-BKN FL150-250 skies in place over western portions by 12Z. these clouds will then spread east of the Divide, becoming FEW-SCT by 18Z. Any convection Saturday afternoon will be very isolated, with KJAC and KCOD having the best chances. With that said, chances remain too low to include in a PROB30 group at this time. There is a chance for showers/thunderstorms to pass over KJAC at times between 00Z and 06Z, but again confidence remains too low to include in the forecast at this time. Wind gusts of 20 to 30kt will return between 17Z and 19Z for all terminals, decreasing again around 01Z/02Z with light winds (11kt or less) returning through the end of the forecast period. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .RIW WATCHES/WARNINGS/ADVISORIES... Red Flag Warning from 11 AM to 8 PM MDT Saturday for WYZ280. && $$ UPDATE...Wittmann DISCUSSION...Straub AVIATION...LaVoie