504 FXUS65 KRIW 091929 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 129 PM MDT Tue Oct 9 2018 .SHORT TERM...(This evening through Friday) Issued at 100 PM MDT Tue Oct 9 2018 The next system is already spreading some light snow into the far west with the main upper low edging towards far wrn Idaho. Satellite pictures still show a pretty potent system but morning analysis of the thermal profile aloft was not that impressive so I still expect the system to pack quite a punch as it enters southwest WY but it should weaken and open up quickly by Wed aftn. Dynamics are still pretty solid for the swrn corner with Kemmerer seeming to be in the center of the best dynamics and upslope along the Bear River Divide. Potential for some warning amounts around Kemmerer so that area the hardest. Sweetwater looks like a decent advisory when combined with the gusty ene winds of 20 to 35 mph. South Pass is near the nrn edge of the better forcing but hopefully combination of ne winds to 40 mph along with at least a short period of moderate snow will make it quite dicey for a few hours. Lander is even more on the edge. Upslope looks decent for a while but forcing from this system is weak since the low is opening up so quickly. Keeping amounts in the 2 to 3 inch range but confidence is not high on those amounts. Much less the farther north you go in the basin. Some areas may see nothing or just flurries in the north half. I80 could be quite interesting for a few hours Wednesday morning with the band of heavier snow expected and gusty ene winds. This system falls apart quickly but a moist, cyclonic flow will keep snow going in the mountains through Thursday, mainly the nw mtns with additional accumulation. Depending on cloud cover which still looks like a lot, a season ending freeze may hit areas east of the divide Wed ngt. Next shift can look at this again. Friday is our 'quiet' day before the next system arrives Saturday. More on that below. .LONG TERM...(Friday night through Tuesday) Issued at 100 PM MDT Tue Oct 9 2018 The next weather system and cold front moves into northern WY after midnight Fri night and into central WY during Saturday morning. The front pushes into the south during Saturday afternoon. There is usually a period of moderate snow for a few hours with a system of this nature along with a gusty north wind and falling temps behind the cold front. Models have come into closer agreement in terms of timing and placement so snow is forecasted across a wider area during the day Saturday east of the divide. West of the divide, scattered snow will occur with the cold front passage with lesser impact. Snow will decrease and end from north to south Saturday night leading to a cold start to Sunday. Sunday should be dry for most locations with a few mountain snow showers possible over the higher peaks. Cold day on Sunday. Monday will be dry and milder for all areas. Then there is the potential for another weather system and cold front passage next Tuesday, but as far out as it is will keep and pops in the northern mountains. Colder highs next Tue. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday afternoon) Issued at 100 PM MDT Tue Oct 9 2018 West of the Continental Divide...(KJAC, KRKS, KBPI, KPNA) The weather system moving through Idaho will continue to overspread the area with snow showers over the west, and then spreading southeast this evening. The best chance of snowfall looks to be from KKMM to KRKS after 06Z Wednesday. Overall KJAC seems again to be the least impacted Terminal although cannot rule out a period with MVFR conditions late in the afternoon/evening. East of the Continental Divide...(KCPR, KCOD, KRIW, KLND, KWRL) Low ceilings have hung around at several terminals longer than expected so will continue MVFR conditions into the evening. Another storm system moving into the area tonight will result increasing clouds this evening with MVFR/IFR ceilings developing in most locations, except perhaps part of the Big Horn Basin. IFR conditions in low ceilings and/or vis in snow could develop at KLND by around 08Z Wednesday. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .FIRE WEATHER... Issued AT 100 PM MDT Tue Oct 9 2018 A cool and moist pattern will persist through at least Thursday. The next new storm system will spread another round of snow into the southwest and west this afternoon and evening then rapidly spread across the south and central portions overnight and continue into Wednesday before exiting the area. This next system will be a quick hitting, potent system with widespread snow across the Salt/Wyoming Range, Wind River Mountains and most of southwest and south central Wyoming up into parts of Fremont and Natrona Counties. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from midnight tonight to noon MDT Wednesday for WYZ030. Winter Weather Advisory from 9 PM this evening to noon MDT Wednesday for WYZ026-028-029. Winter Weather Advisory from 6 PM this evening to noon MDT Wednesday for WYZ027. Winter Weather Advisory until 3 PM MDT Wednesday for WYZ024. Winter Weather Advisory from 6 PM this evening to 3 PM MDT Wednesday for WYZ014-015. && $$ SHORT TERM...Skrbac LONG TERM...Hulme AVIATION...Hulme FIRE WEATHER...Skrbac