362 FXUS65 KRIW 310902 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 202 AM MST Sun Dec 31 2017 .SHORT TERM...Today through Tuesday night Snow has ended across the area, with areas of low stratus across Johnson/Natrona counties, the Big Horn Basin and northern portions of the Wind River Basin. Ceilings for these clouds generally range between 010-020 AGL, but have dropped to the surface here at KRIW. This appears to be isolated so far, based on webcams in the surrounding areas. This should lift by noon, with remaining clouds clearing from the area through the rest of the afternoon. Skies have cleared over the rest of the area, as temperatures continue to drop. Conditions will be mainly dry through the rest of the forecast period, along with light winds. As frigid as temperatures are currently, winds of 5 to 10 mph will be enough to bring wind chills of -20 to -30F across northern and eastern portions. Similar conditions will return New Year's Eve (Sunday night) and Monday night. As previously mentioned, skies will become mostly clear across the area by this afternoon. Clouds will briefly return across the area on New Year's Day, ahead of a fast moving cold front. No precipitation is expected with this front and skies will clear out once again Monday night. .LONG TERM...Wednesday through Sunday Dry weather Wednesday with moderating temperatures. Thursday will be dry for most places. A weak weather disturbance is forecast to move through the area Thursday. Any snow would be in the western mountains and quite light. High temperatures seasonal. On Friday, the GFS has some moisture moving into the west again producing some light snow in the mountains and scattered light snow in the far west valleys. The ECMWF model is dry on Friday. Have kept this chance of snow for now and will see how things look tonight. Dry east of the divide on Friday. A little milder high temperatures on Friday. A potentially stronger weather system is forecast to move into west Saturday afternoon and through the whole area Saturday night and next Sunday. A chance of snow in the west Saturday into Sunday morning with snow tapering off Sunday afternoon. East of the divide, a chance of snow late Saturday night and next Sunday. High temps a little colder in the west Saturday and still mild east of the divide. Then colder all areas next Sunday. && .AVIATION...For the 12Z TAFS through 12Z Monday West of the Continental Divide...KJAC, KBPI, KPNA and KRKS VFR conditions with mainly clear skies are expected. Winds are expected to be mainly light. East of the Continental Divide...KCPR, KCOD, KRIW, KLND, and KWRL Widespread MVFR/IFR ceilings, with some flurries ongoing this morning, are expected to scatter out by late morning into the early afternoon. However, some low ceilings could redevelop across Natrona early this evening. For now, will only hint at this possibility in the CPR TAF. Farther west, patchy fog could develop tonight, but increasing mid-level clouds should limit the extent of any fog. Winds will be mainly light. && .FIRE WEATHER... Fuels remain at critical levels across over portions of Johnson and Natrona Counties. The period will be marked with frigid temperatures, especially east of the Divide, with dry conditions and light winds. Temperatures are expected to moderate to more seasonal readings by the middle of the week. && .RIW WATCHES/WARNINGS/ADVISORIES... Wind Chill Advisory until 8 AM MST this morning for WYZ003-004- 010-011-020. && $$ SHORT TERM...LaVoie LONG TERM...AR AVIATION...Murrell FIRE WEATHER...LaVoie