888 FXUS65 KRIW 142024 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 224 PM MDT Sat Sep 14 2019 .SHORT TERM...This afternoon through Sunday The main concern this weekend will be fire weather, where low humidities and gusty winds will occur during the afternoon across the southwest to central areas. Thus, Red Flag Warnings will be in effect today and Sunday. Gusty winds will also occur over areas west of the Divide, including the mountains. Gusty winds will continue over the mountains, as well as the Wind Corridor, through the overnight hours tonight. Of particular note, will be the winds over Outer Drive in Casper and Casper Mountain. Winds with gusts of 30 to 35 mph will be common in these areas, continuing through the day Sunday. Gusty winds will be more widespread Sunday, as well. A return to summer (the equinox is on the 23rd) for the weekend. Coincidentally, forecast highs Sunday will be similar to what occurred last year. 3 record highs were set on 9/15/18 at Buffalo, Riverton, and Worland airports with 94, 90, 94 respectively. Hot temperatures, with near record heat on Sunday, as 700 mb temperatures warm between 13 and 15 Celsius. .LONG TERM...Sunday night through Friday Sunday night the longwave trough will begin moving into the Pacific Northwest. This upper level system will bring some isolated showers and thunderstorms to the western mountains by Monday afternoon. A tightening gradient will also bring gusty winds across the area, especially in the mountains and in the wind corridor from Rock Springs to Natrona County. Luckily a good amount of moisture will be advecting in an RHs will remain above 20 percent in most areas which will alleviate fire weather concerns. Tuesday morning the cold front quickly enters western WY and then blast through the state during the day. The trough axis also passes over WY Tuesday causing the pressure gradient to tighten again and winds to become breezy to quite gusty across the entire area. Precipitation chances will be greatest in the northwest, but chances will spread throughout the state. Tuesday evening snow is likely in higher elevations, as 700mb temps drop to around -1 to -2. This could bring the snow level into the 7500-8000 ft range in the west. Wednesday is still looking fairly dry across the state but models are indicating a cut-off low forming on the west coast and some weak shortwaves could bring tome activity to the northwest mountains. Thus, we left some low end pops in that area. The cut-off will eject Thursday into Friday so left some slightly higher pops on Thursday and a more direct impact Friday. Friday into Saturday will see more wind, cooler temperatures, and precipitation as the ejecting system moves through. && .AVIATION...For the 18Z TAFS through 18Z Sunday Issued at 1200 PM MDT Sat Sep 14 2019 VFR conditions will occur through the period. A gusty wind will impact TAF sites in the west and south. Central and northern TAF sites may see some isolated lighter gusts. Wind gusts should end around 01Z Sunday. Clear skies and light winds are expected the rest oF tonight into Sunday morning. Gusty winds will pick back up Sunday afternoon in many of the same locations. && .FIRE WEATHER... Unseasonably warm and very dry conditions will result in elevated to critical fire weather conditions across the area this afternoon and Sunday. Red Flag Warnings are in effect today and Sunday, for zones, 277, 279 and 280. Gusty winds will occur over all, but the central basins this afternoon. Winds will remain gusty, southwest 15-30 mph, over the mountains and Wind Corridor tonight. Gusty winds will become widespread by late Sunday morning once again. Temperatures will be well above normal Sunday, with RH values ranging between 10 and 15 percent in the lower elevations (including zones where fuels are no longer critical). && .RIW WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 7 PM MDT Sunday for WYZ277-279-280. && $$ SHORT TERM...LaVoie LONG TERM...Hulme AVIATION...Hulme FIRE WEATHER...LaVoie