684 FXUS65 KBYZ 221617 AFDBYZ Area Forecast Discussion...Updated National Weather Service Billings MT 1017 AM MDT Wed May 22 2019 .UPDATE... High pressure nosing in from the north and the upper low shifting off to the north and east has allowed rain and snow to diminish over portions of the area this morning, with rain and snow lingering along the mountains and foothills, as well as SE Montana. Showers will remain possible through the day as additional energy moves over the area. Greatest precipitation chances will be along the southern mountains and foothills, into southeastern Montana. Only expecting minor additional snow accumulations along the foothills, so have allowed the winter weather highlites to expire there. Several inches of additional snow can be expected over the mountains today, and have continued the Winter Storm Warnings there. Have updated the pops, snow amounts, wind, and temperatures to current trends. The rest of the forecast remains on track and the previous forecast discussion and an updated aviation discussion are below. STP && .SHORT TERM...valid for Tdy and Thu... Showers will slowly move out of the area by Wednesday night, bringing a brief, relatively dry period for Thursday, until another round of showers look to occur over far SE Montana. OVERVIEW: As an upper low moves NE from South Dakota, it brings with it the moisture and forcing needed for widespread showers over SE Montana. QPF amounts are lower than previously forecasted, with amounts less than half an inch above a line from the ND-SD border to Livingston, and amounts up to an inch south of that line. That being said, 5-8 inches of snow are expected at Red Lodge and higher areas of the Beartooth foothills through the morning, hence the Winter Weather Advisory has been upgraded to a Winter Storm Warning for that area through Wednesday morning. Precipitation will generally move out of the area by Wednesday night, and conditions will be relatively dry until a second upper low looks to move north over the Rockies from the SW CONUS and through the area Thursday night through Friday morning. Although again bringing more moisture to our area, only far southeastern Montana looks to receive up to half an inch of rain Thursday night into Friday morning, mainly in Fallon and Carter counties. Due to the decrease in overall precipitation, the Flood Watch has only been continued for southern Bighorn and Rosebud, Powder River, and Carter counties, as well as Sheridan county in Wyoming, and only continues through Wednesday. Temperatures will gradually increase, reaching the mid 50s on Wednesday and Thursday. CONFIDENCE: QPF amounts have greatly decreased due to the upper low being displaced further east from Montana than anticipated, hence less moisture and forcing is present for the precipitation to act upon. GEFS and the NBM are in fairly good agreement for the second upper low on Friday to only bring an abundance of moisture and forcing to far SE Montana for a second round of showers, and half an inch or less can be expected there, with minor accumulations west of there, including Billings. Thursday evening into Friday morning is the agreed upon timeframe for that precipitation event. IMPACTS: Although precipitation amounts have decreased, flooding in low-lying areas, such as ditches, roads, and smaller creeks is expected to occur over the next 24 hours. Heavy, wet snow in the Beartooth foothills may cause transportation issues during the Wednesday morning commute and brief power outages, but snow is expected to melt during the day. Vertz .LONG TERM...valid for Fri...Sat...Sun...Mon...Tue... Unsettled conditions will persist through the extended period, with temperature trending warmer. Upper low crossing the area Friday looks drier as the previous system has cut off a good deal of the deep moisture for it. Still looking at widespread precipitation east of Billings, but accumulations look to be about a quarter of what had been advertised. Saturday is turning into a pretty nice day with ridging aloft helping break up cloud cover and get some sunshine into the area. Will have to deal with isolated to possibly scattered showers as the sun works on residual moisture from recent rainfall, but doesn't look like a wash out by any means. Highs reflect the decrease in cloud cover with latest guidance in the mid to upper 60s. Weak cold front gets pulled into the area Sunday by deepening storm system over the Great Basin. The front plus better forcing aloft will bring scattered to numerous showers, and a few weak thunderstorms, to the area Sunday afternoon into Sunday night. Great Basin storm system pushes across Wyoming on Monday, putting southern Montana/northern Wyoming in good position for more widespread precipitation into Tuesday and maybe Wednesday. While temperatures will be warmer than the current system, they will be cold enough for accumulating snow in the mountains. This may impact travel over the Beartooth Highway as well as over the Bighorn mountains. Chambers && .AVIATION... Precipitation has tapered off across much of the lower elevations with showers lingering along the foothills. Conditions have improved to VFR from KBIL to KBHK with possible IFR for KLVM and KSHR with any rain/snow showers. Showers will continue east of KMLS but conditions are not expected to drop below MVFR. Carrothers && .PRELIMINARY POINT TEMP/POPS... Tdy Thu Fri Sat Sun Mon Tue ------------------------------------------------------- BIL 055 040/056 042/060 043/067 046/060 046/060 046/063 5/W 65/R 64/T 13/T 34/T 55/T 43/T LVM 050 036/052 037/059 039/062 042/058 042/059 042/062 7/W 65/R 43/T 35/T 56/T 56/T 44/T HDN 054 038/056 042/060 040/067 044/062 045/061 044/063 5/W 55/R 66/T 13/R 25/T 55/T 44/T MLS 057 039/058 042/058 040/067 045/062 043/060 044/064 3/W 24/R 88/R 01/U 14/T 45/T 33/T 4BQ 048 037/054 041/057 039/066 044/064 045/059 043/060 9/W 45/R 75/T 01/U 15/T 46/T 43/T BHK 051 036/056 040/055 038/064 042/061 040/056 041/060 8/W 23/R 87/R 11/U 14/T 34/T 32/T SHR 046 033/050 037/057 036/064 041/062 043/059 042/060 8/W 87/R 73/T 13/R 25/T 56/T 44/T && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...Flood Watch in effect through this evening FOR ZONES 36>38-58. Winter Storm Warning in effect until 10 AM MDT Thursday FOR ZONES 67-68. WY...Flood Watch in effect through this evening FOR ZONE 99. Winter Storm Warning in effect until 10 AM MDT Thursday FOR ZONE 98. && $$ weather.gov/billings