685 FXUS65 KRIW 280711 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 111 AM MDT Tue Aug 28 2018 .SHORT TERM...Today through Thursday night Rain showers from southern portions of the Bighorn Basin to Natrona County will be ongoing this morning, with these showers gradually ending from northwest to southeast through the rest of the morning. Elsewhere, areas of frost, freezing temperatures and patchy fog are expected over the western valleys, including Pinedale and Bondurant, as skies clear this morning. Otherwise, a brisk day for late August across the Cowboy State with temperatures generally in the 60s. Unfortunately, elevated fire conditions will return across portions of southern Lincoln and western Sweetwater counties this afternoon. This trend will spread across much of the forecast area Wednesday, as temperatures warm back into the 70s and lower 80s. Red Flag conditions look to be in place over southern and eastern zones, west to southwest winds with gusts over 25 mph will occur over these areas. Thus, will issue a Fire Weather Watch for the southern zones. Conditions are expected to remain dry through the forecast period, with isolated showers/thunderstorms possible over eastern portions late Thursday afternoon/early evening. .LONG TERM...Friday through Tuesday Some energy over Siberia works across AK on Wed and continues to dive se towards another trough that moves out of AK and into MT/srn Canada on Thursday. This energy/pocket of cold air holds the trough back in the area (well to the north though) through Fri. A cold front arrives in the north Thu ngt and then likely dives south into our central zones during the day Fri. Some moisture and weak instability remains mainly across the north half Friday and in srn/sern Sweetwater County aiding in some showers/storms. The tail end of an associated jet across ND back into far nrn WY may also provide some right entrance region support up north while a jet across the far south could provide some left exit region in ern Sweetwater Friday. The tail end of this trough may linger a few showers into the early morning hours Saturday in our far nern/ern zones. Saturday looks dry and mild with highs in the 70s and lower 80s across the lower elevations with mainly 60s in the high country. On Sunday, the GFS is still trying to bring some energy in from the west resulting in some tstm potential but the evolution of this (some energy from a system over the ern Pacific) is shaky at best. Not that it couldn't happen but it's the only one that shows that much potential. A general mean trough over wrn Canada down into the Pacnw with a generally wly flow underneath is somewhat conducive to energy coming in from the west though so we'll have to see. The system for Labor Day into at least part of Tuesday originates from Kamchatka where an upper low currently sits. The remnants of this system swings across MT and srn Canada with most of the energy currently forecast to stay to the north. The GFS 5-wave has backed off on the srn extent of the developing mean trough and now it further to the north along the Canadian border and nwd. With this trend, it does not appear right now that a significant Labor Day system is in the offing. We will likely see a cold front move swd around Monday night aiding in some cooling east of the divide for Tuesday. Models are generally dry but they are showing some mid level moisture being drawn ne across the area so with time they may show a few more showers but forecast is fairly dry for now. && .AVIATION...For the 12Z TAFS through 12Z Wednesday East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Routes MVFR ceilings with mountain obscurations are expected over parts of the area through mid-morning. The best chance of MVFR ceilings will be across the Cody and Lander Foothills, and across Natrona County. Ongoing valley rain/mountain snow over the north is expected to decrease in coverage from west to east between 10Z and 15Z. By 18Z, VFR conditions are expected with skies becoming mainly SKC by midday into the early afternoon. West of the Divide...KBPI/KJAC/KPNA/KRKS Routes Valley rain/mountain snow over northwest Wyoming should end by around 09Z. The associated low ceilings should begin to lift/scatter out as well during the predawn hours. Once skies begin to clear, some fog/low ceilings could quickly form across the western valleys. The fog/low clouds should dissipate/lift by around 15 or 16Z. After 18Z, expect mainly SKC with mainly light winds. && .FIRE WEATHER... Apart from ongoing rain showers from the Bighorn Basin to Natrona County this morning, conditions will be dry today. These showers are expected to end by noon today. Areas of frost, freezing temperatures and patchy fog are expected over the western valleys, including Pinedale and Bondurant, as skies clear this morning. Temperatures will be 5 to 10 degrees warmer west of the Divide and 5 to 10 degrees cooler east of the Divide. A Fire Weather Watch will be in effect for Wednesday afternoon and evening across southern zones. && .RIW WATCHES/WARNINGS/ADVISORIES... Fire Weather Watch from Wednesday afternoon through Wednesday evening for WYZ277>279-289. Winter Weather Advisory until 6 AM MDT early this morning for WYZ001-002-008-009-012-014-015. && $$ SHORT TERM...LaVoie LONG TERM...Skrbac AVIATION...Murrell FIRE WEATHER...LaVoie