FXUS65 KRIW 141659 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 1059 AM MDT Tue Apr 14 2026 .KEY MESSAGES... - Light snow shower chances (20%) exist through 6PM MDT across the western mountains, the Bighorns, and Casper Mountain. A light drizzle cannot be ruled out in Casper. - A potent winter storm is forecast to bring widespread precipitation, wind, and freezing temperatures to the entire area beginning late Wednesday until Friday evening. Confidence in measurable snowfall continues to increase for low elevations. - There is high (90% +) confidence in a hard freeze (28 degrees or below) across low elevations Friday morning and Saturday morning, with the potential for widespread lows in the teens on Saturday morning. && .DISCUSSION... Issued at 145 AM MDT Tue Apr 14 2026 Finally a more active pattern across Wyoming trying to bring precipitation! The latest system is a trough ejecting into the central Plains from the Four Corners region. This system is set a little too far south to bring a significant amount of precip, but still enough energy to produce precip for areas of Casper Mountain, the Bighorns, and higher elevations of the Tetons. But this does set the table for a potent late winter storm diving out of the PacNW into the northern Rockies. This system starts to spread precip into the NW mountains during the day Wednesday before slowly moving east Thursday and Friday. The system will be accompanied by ample moisture, so the potential for meaningful accumulations is improving. The system will also be accompanied by a strong push of colder air, so most precip will be snowfall, especially Thursday night into Friday. This includes most of the lower elevations as well, with the current forecast totals of 2 to 5 inches. Winter Storm Watches have been posted for the northwestern Mountains and YNP for this system, and may need to be expanded is the snow forecast increases with later updates. The other concern with this next system is the significant cold air push coming with and behind the next system. Cold temperatures will arrive during the day Thursday, with lows Thursday night in the low to mid 20s east of the Divide and in the teens west of the Divide. The main core of the cold air then settles in on Friday, with the core of the cold air setting in Friday night. Probabilities of temperatures falling below 28 degrees are high (>90%), with current forecast lows reaching the teens. The complicating factor will be how quickly cloud cover clears out behind the weather system, allowing for radiational cooling. If clouds hold longer, these teens would likely not be achieved. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 1057 AM MDT Tue Apr 14 2026 VFR conditions are expected to prevail across nearly all terminals through much of the TAF period. The one exception to this currently is KJAC where some linger low level clouds persist. Conditions should continue to improve shortly after the start of the period with VFR conditions likely to return. A shower or two cannot be ruled out around 21Z Tuesday nearby KJAC. Due to low confidence in direct impacts at the terminal only a VCSH group has been added. Winds gradually increase this afternoon with nearly all terminals seeing winds of 15 to 25 knots. These winds should dissipate shortly after sunset with light winds around 5 to 10 knots persisting through the overnight. A nearing disturbance will start to usher in more cloud coverage for Wednesday. Winds will begin to increase near the end of the TAF period mainly across northern and western terminals. Mountain obscuration will linger mainly across western mountain ranges as low clouds continue to burn through the early afternoon with improvement expected by the mid afternoon. 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... Winter Storm Watch from Wednesday evening through late Thursday night for WYZ001-002-012. && $$ DISCUSSION...Straub AVIATION...Dziewaltowski