959 FXUS65 KRIW 100553 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 1053 PM MST Sat Nov 9 2019 .SHORT TERM...(This evening through Sunday) The 20Z surface analysis indicated that the strong cold front was extending mainly west to east across northwest through northeast Montana. Further south across western and central Wyoming this afternoon, temps were well above normal and ranging from the upper 40s to mid to upper 50s. Strong warm advection ahead of the cold front was resulting in strong and gusty winds along the wind corridor occurring from KRKS to KCPR. Have highlighted the gusty winds with a special weather statement until this evening for Natrona county. The models are more in line today in moving the cold front progressively southward through the northeast and northern sections of the forecast area by around the 17Z-18Z time frame on Sunday. The models customarily pushes the cold front south through the forecast area by after 18Z Sunday with the models building in QPF values around a tenth to close to two tenths of an inch across mainly Johnson toward Big Horn and into Natrona counties. Will continue more toward the middle ground of the GFS model, compared to the slightly wetter solution by the ECMWF model. The progressive nature of cold front moving southeast through the region will result in some accumulations especially in Johnson and Natrona and into the Bighorn mountains. Still expect that snowfall accumulations will range from 2-4 inch amounts in Johnson and Big Horn counties and will highlight with a special weather statement, as amounts should fall below winter weather advisory criteria for these areas between Sunday afternoon and early Monday morning. For now, will hold off on issuing any Winter Weather Advisories based upon recent trending. Expect falling temps from north to south across the area on Sunday especially by early afternoon and this will be difficult to time across the forecast area. .LONG TERM...Sunday Night through Saturday The cold front will continue moving southward through the forecast area overnight into Monday with the snow ending early in the morning. The main area of snow will be along the Bighorn Mountains and in Johnson and Natrona counties. Behind this front will be cold temperatures. Highs will only reach into the upper 20s to low 30s. We lowered the temperatures a bit for Monday and Tuesday from the models as this air is coming from a fairly cold Canada. Morning lows will be down in the teens to single digits both Monday and Tuesday. High temperatures in the south and southwest are expected to climb into the mid 30s to low 40s for the early week, as the main push of cold air will most likely stay east of the Divide. A front from the Pacific will move into the state late Tuesday into Wednesday, allowing high temperatures to recover back into the 30s and 40s both days. H7 temperatures are showing a slight warmup with the change in flow. This next system will also bring the next chance of snow and much stronger winds winds on Wednesday across the forecast area. Thursday and Friday will see ridging and warmer temperatures. It will be mainly dry, although a fast moving short wave will skirt across the northern forecast area Friday morning. The GFS is hinting at some light precipitation for the northwest, but with the mean upper-level ridge in place would expect only some clouds with this system. Late Friday into Saturday there will be a large scale trough impacting the western U.S. and Rockies. This system will give the entire area a chance of precipitation which is good news for the western mountains which have remained bone dry so far this November. The precip looks to be mountain snow, with a mix of rain and/or snow in the valleys changing to snow. For now will broad brush mainly slight PoPs Friday night and Saturday. && .AVIATION...(For the 06Z TAFS through 06Z Monday) West of the continental divide...KRKS, KJAC, KBPI, KPNA Terminal sites. VFR conditions will occur through the forecast period at the terminal sites. Some snow showers will occur over the NW WY mountains and the Wind River mountains Sunday afternoon and evening with MVFR conditions and partial mountain obscuration. A cold front will push through KRKS terminal site around 05Z with a wind shift to the northeast behind it. East of the continental divide...KCPR, KLND, KRIW, KCOD, KWRL Terminal sites. VFR conditions will occur at the terminal sites through 18Z. A cold front will move into northern WY by 18Z. This front will move south during Sunday afternoon and be along the continental divide by 01Z Mon. Ceilings will be decreasing to MVFR to IFR Sunday afternoon and early evening and continue through Sunday night. Snow will develop over the north Sunday afternoon and spread into the central Sunday evening. Expect mountains to be frequently obscured Sunday afternoon and night. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .FIRE WEATHER... Expect dry and warm weather today. Natrona and Sweetwater counties, as well as the lee of the Absaroka Mountains will see gusty winds through late tonight. Relative humidity will remain above critical levels. Mixing and smoke dispersal will be generally fair to poor. A cold front will drop southward across the state Sunday and bring some snow and colder temperatures, especially East of the Divide. && .RIW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...Troutman LONG TERM...Swanson AVIATION...AR FIRE WEATHER...Swanson