821 FXUS65 KRIW 051841 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 1241 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 (around and less than 10 percent). - Warm today and Saturday, with peak heat occurring Saturday. Highs today in the 80s to low-90s, with highs Saturday in the mid-80s to near 100 degrees. - 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. && .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 that 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 /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1135 AM MDT Fri Jun 5 2026 Upper-level high pressure over Wyoming today has brought very clear skies with VFR conditions at all TAF sites. Breezy/gusty southwest winds are expected at most sites this afternoon, with some gusts reaching 20-25 kts. High-level clouds will move into western WY between 06/03-06Z this evening and spread eastward through the night into Saturday morning. They will thicken as a storm system approaches from the Pacific Northwest on Sunday. Mid-level clouds are also expected across western and northwest WY Saturday, but VFR conditions should prevail. As moisture increases through the day, northwest WY from the Tetons to the northern Absarokas should see some light showers Saturday evening. Southwest surface winds will increase by 06/17Z and increase by 06/19Z to 10-20 kts with 20-30 kt gusts at nearly all TAF sites. 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...McDonald