KRIW issues Area Forecast Discussion (AFD) valid 2019-11-27T10:30:00Z 493 FXUS65 KRIW 271030 CCA AFDRIW Area Forecast Discussion...CORRECTED National Weather Service Riverton WY 326 AM MST Wed Nov 27 2019 .SHORT TERM...Today through Thursday A major storm system developed over OR/CA earlier Tuesday. This storm system will impact the Intermountain West through Friday, before exiting over the Northern Plains by Saturday. An extensive cloud shield extends from E WA southward over ID and into N UT/NV. The leading edge of snow is currently moving over the I-15 corridor between SLC and PIH. This will be part of the first wave of snow that will move over SW portions this morning and will continue over far W portions into Thursday. 2 to 3 inches of snow is expected during the day today over portions of Lincoln and Sublette counties, including Star and Jackson Valley. Up to 5 inches could fall over the west side of the Wind River Mountains, Gros Ventres and Salt/Wyoming Ranges today. Locally higher amounts could fall on the southern end of the Tetons. Otherwise, temperatures will remain cold across much of the area. S to SE winds will increase across much of the area, with gusts of 25 to 30 mph occurring from Rock Springs to Buffalo. Snow will become very light over the west this evening, with an additional inch of snow possible in the lower elevations through the overnight period. 1 to 2 inches expected in the mountains. This trend will continue through the day Thursday, with additional amounts of 1 to 2 inches in the lower elevations and 2 to 3 inches in the mountains. Continued SW flow aloft will modify the temperatures Thursday, with southern portions, along with Johnson, Natrona and Sublette counties and the western valleys rising above freezing. Due to the prolonged nature of the snow, expected break this evening and possibility of above freezing temperatures Thursday, will issue a Special Weather Statement for the affected areas for now. .LONG TERM...Thursday night through Tuesday Southwest flow will keep an active weather pattern across the forecast area, with a fairly steady stream of moisture. The storm center that is currently over OR/CA will finally begin to move eastward Friday. A strong wave rounding the base of the trough will kick out over the Four Corners during the day Friday. Other shortwaves will continue to move over western portions Friday morning, as the trough axis becomes negatively tilted. Snow will spread to areas east of the Divide Friday afternoon, as leeside cyclogenesis forms a surface low over northeast CO by 00Z Saturday. The models agree on a more widespread and significant snow event, which will spread across much of the region by Friday night. For now, a Winter Storm Watch has been issued for this storm, beginning in western and central Wyoming, and then spreading eastward. Exact locations and snow amounts will be monitored and updated, as the storm gets closer. The potential for strong winds will be possible over Johnson and Natrona counties. The Bighorn and Wind River Basin may also be affected by these winds Saturday, as snow ends. Cold temperatures will continue through the week. Still looking at a mostly dry Saturday night and Sunday, as a weak ridge builds across the area in the wake of the exiting storm. The west is going to see another system move in as early as Sunday night for more snow in that area. On a more positive note, the high temperatures for the beginning of next week will make a nice recovery, reaching the low 30s to near 40, everywhere except the northwest, which will be closer to 30 degrees. && .AVIATION...For the 12Z TAFS through 12Z Thursday West of the Continental Divide...KRKS, KJAC, KBPI, KPNA Terminal sites. VFR conditions will continue through this morning. Light snow will develop early Wednesday morning at JAC, but impacts will likely hold off until around 14Z when more widespread snow brings MVFR to possible IFR across the west, including KPNA and KBPI after around 17Z. Mountain obscuration is likely through the entire period. East of the Continental Divide...KCPR, KLND, KRIW, KCOD, KWRL Terminal sites. LIFR visibility in fog for KRIW initially, lifting after sunrise, Low stratus deck over KLND will also clear out after around 14Z. Otherwise, VFR conditions for all of the sites through the period. There will be increasing clouds through the day Wednesday, and lowering through the evening and overnight. Mountain obscurations possible starting Wednesday afternoon as lower clouds move into the west. && .FIRE WEATHER... Cold and breezy conditions will be in place today and Thanksgiving, with light snow over the far west. A major storm system will impact the area Friday and Saturday, with areas of moderate to heavy snow possible. Strong winds will also occur Friday night into Saturday for areas east of the Divide and possibly zone 279. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Storm Watch from Friday morning through Saturday morning for WYZ003>007-017>019. Winter Storm Watch from Friday morning through late Friday night for WYZ012>016-023>025. Winter Storm Watch from Friday afternoon through Saturday afternoon for WYZ008>011-020-022. && $$ SHORT TERM...LaVoie LONG TERM...Swanson AVIATION...Murrell/Swanson FIRE WEATHER...LaVoie