FXUS65 KBYZ 210752 AFDBYZ Area Forecast Discussion National Weather Service Billings MT 152 AM MDT Sun Jun 21 2026 .KEY MESSAGES... - Unsettled conditions through Monday. Highest chances for significant precipitation (half an inch or more) will be east of a Forsyth to Sheridan, WY line. - Seasonal weather conditions, with low chances (10-30%) for afternoon and evening showers and thunderstorms, expected for the rest of the work week. Temperatures approaching 90 degrees by Friday. - Strong storm system taking shape for next weekend. Stay tuned. && .DISCUSSION... Today through Saturday... Shortwave energy moving though southern MT has brought a few strong thunderstorms this evening. Radar estimated amounts of 1 to near 2" have fallen in southern Powder River County. Strong storms are not expected overnight, but light to moderate rainfall is expected to continue as the boundary over southeast MT moves east overnight. With this, showers will continue across southeast MT through the morning (50-70% chance). Ensembles give that region around 0.4-0.8" of additional precipitation, with locally higher amounts under thunderstorms, through Sunday. With this wave of departing energy, Hi-Res ensembles are showing weak shear and instability for southeast MT, giving a signal for a few weak thunderstorms this afternoon. Drier air is expected to move in aloft, slightly decreasing the threat for heavy rain, although storms will be slow moving. The last piece of energy associated with this low is expected to move through overnight tonight into Monday morning bringing another round of scattered showers with isolated thunderstorms possible into Monday afternoon. The environment Monday afternoon looks favorable for strong to severe thunderstorms across southeast MT and northern WY. This will be something to watch as precipitable water values range from 0.75-1" giving way to the possibility of heavy rain under any stronger thunderstorms. For the days following, ensembles generally show weak energy moving overtop of the ridge. By Friday ensembles bring in Pacific troughing. There's still uncertainty on the track of the potential low, but additional beneficial precipitation could be in store. Temperatures will generally remain seasonal for the first half of the week, warming into the 80s to near 90 by the second half of the week. TS .AVIATION... Scattered to numerous showers and isolated to scattered thunderstorms will persist over eastern areas through this afternoon as a disturbance remains over the region. Look for mainly isolated showers/thunderstorms over the rest of the area. MVFR to IFR conditions and gusty winds are possible with the strongest shower and thunderstorm activity. Stratus will move into eastern areas early this morning, including KMLS and KBHK producing MVFR ceilings. Expect the ceilings to lift during the afternoon hours, with VFR conditions prevailing for most areas, outside of convection bringing local reductions. STP && .PRELIMINARY POINT TEMP/POPS... Tdy Mon Tue Wed Thu Fri Sat ------------------------------------------------------- BIL 078 055/071 051/076 051/080 055/085 057/091 059/079 1/B 47/T 20/U 00/U 02/T 21/B 46/T LVM 077 046/072 043/076 045/079 047/084 050/086 049/072 0/U 25/T 20/U 10/B 13/T 22/T 47/T HDN 078 053/072 048/075 048/079 051/085 055/091 057/080 3/W 48/T 10/U 00/U 12/T 31/B 35/T MLS 073 051/070 049/072 047/074 050/081 056/087 059/080 8/T 29/T 20/U 00/U 01/B 32/T 43/T 4BQ 070 051/071 049/071 047/074 051/080 056/087 059/081 7/T 29/T 40/U 01/U 22/T 41/B 45/T BHK 067 046/070 045/069 043/072 045/076 051/081 054/080 8/T 28/T 50/N 00/U 01/B 32/T 44/T SHR 075 048/071 045/071 044/075 047/080 050/088 054/078 6/T 5+/T 62/T 24/T 35/T 31/B 36/T && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$ weather.gov/billings