Expires:No;;402143 FXUS65 KRIW 261138 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 538 AM MDT Fri Apr 26 2024 .KEY MESSAGES... - Showers and isolated thunderstorms today and Saturday, most numerous in central and southern Wyoming. The steadiest precipitation will be tonight, - Snow is likely in the mountains, with the heaviest in the Wind River and Absaroka Ranges. - Remaining rather unsettled through Wednesday, with a few chances for showers and the potential for strong wind Monday through Wednesday. && .DISCUSSION... Issued at 316 AM MDT Fri Apr 26 2024 The pattern looks rather active over the next few days. Radar currently shows some showers mainly across Johnson and Natrona County as I write this around 2 am. And today looks rather damp as we will be under the influence of two low pressure areas. The first is a vertically stacked, slow moving low that is moving out of Colorado and into Nebraska at this time. The second is now moving into the Pacific Northwest and will close off over the Great Basin tonight and into Saturday. This will turn low level flow east to northeast across much of the area and bring in moisture. There are some changes this morning though. For one, the QPF has trended down across portions of the area, especially further east and north in places like Buffalo where the core of the moisture would be further south. Today looks to be more convective, with isolated thunderstorms possible in most areas, but the chance of any spot seeing one is 1 in 3 or less. The steadiest. more stratiform precipitation still looks to be tonight, when moisture flow would be the deepest. The highest amounts still look to occur in the favored east to northeast upslope locations, especially from the east slopes of the Absarokas to the Wind River Range to to Salt and Wyoming Range. Heavier amounts are also possible in southern Wyoming which will be where the best convergence will set up. In the lower elevations, the most favored areas, like Lander, Dubois and even Rock Springs have at least a 1 in 2 chance of picking up a half an inch of rain or more. Amounts would then generally decrease further north and east away from the deepest moisture. Temperatures will be cooler today, but not cold given the Pacific nature of the air mass. Now on to the S word, snow. With 700 millibar temperatures expected to remain at minus 3 or warmer, snow accumulation would be largely restricted to the mountains, with snow levels generally 7500 feet or higher. We can't rule out a small accumulation of snow in places like Dubois or Lander if precipitation rates are very heavy, but accumulation would likely only be on non-paved surfaces. The heaviest snow still looks to fall in the Wind River Range, where areas above 10000 feet may pick up 2 feet of new snow, with around a 9 in 10 chance of over a foot of snow in the highest elevations. We will maintain the Winter Storm Warning here. The advisory for the Absarokas will also be continued, but impacts here would be less, with less than 1 in 3 chance of a foot of snow or more. Unsettled weather will continue into Saturday, although intensity should be less as the low moves away. A new wrinkle is what may happen Saturday evening as the trailing trough axis swings through western Wyoming. Some ensemble solutions are putting advisory amounts of snow in places like the Salt and Wyoming Range. There is poor agreement on this though, with less than a 1 in 2 chance of reaching advisory criteria. This, plus the fact that impacts would be limited, no new highlights will be issued at this time. Things become somewhat, emphasis on somewhat, less active after that. A few showers will linger into Sunday but coverage will be about 50 percent less than previous days. The first part of the new workweek will feature mainly zonal flow. A couple of shortwaves will pass through the flow, most likely on Monday and Wednesday. These may bring a few showers, especially to northern portions of the area. Details on how far they reach are difficult to determine at this time though. The main concern on these days may turn out to be strong to potentially high wind. Flow is fast over the area and the jet will be overhead, helping to enhance downward momentum, especially across the southern half of the state. Way too early for details, but it could be a few days of securing things like trash cans, trailers and toupees. More settled weather is then expected for the end of next week as ridging builds into the area. Temperatures through much of next week should average near to slightly below normal. && .AVIATION /12Z TAFS THROUGH 12Z SATURDAY/... Issued at 533 AM MDT Fri Apr 26 2024 The continuing unsettled weather pattern has kept scattered light rain showers across central Wyoming through the overnight hours. Coverage of precipitation will increase through the morning, with all terminals favored to see shower or thunderstorm impacts this afternoon and evening. Brief MVFR conditions can be expected with this activity through the afternoon, though KCOD and KWRL are likely to see longer periods of MVFR ceilings. Ceilings will generally trend lower near the end of the period, with more persistent MVFR conditions expected for most terminals into Saturday morning. Frequent mountain obscurations are expected through the 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... Winter Weather Advisory from noon today to 3 PM MDT Saturday for WYZ002. Winter Storm Warning from 6 PM this evening to 9 PM MDT Saturday for WYZ015. && $$ DISCUSSION...Hattings AVIATION...Myers