655 FXUS65 KBYZ 060929 AFDBYZ Area Forecast Discussion National Weather Service Billings MT 329 AM MDT Fri Sep 6 2019 .SHORT TERM...valid for Tdy and Sat... Water vapor imagery this morning shows a ridge building over the Northern Rockies but it has considerable moisture within it with radar showing showers and thunderstorms over parts of western Montana and southeast Idaho. A pair of disturbances pushing the ridge quickly northeastward today will track into the area this afternoon and evening which will tighten a surface trough in the lee of the Rockies. Thunderstorms expected to form over the mountains by early afternoon and spread eastward. Given high moisture content a few of the storms could be strong and likely producing wind gusts west of Billings while storms will likely morph into lines of heavier rain producers east of Billings. One area of concern is over Park and Sweet Grass counties where a small jet stream will approach the area this afternoon which may support a storm approaching severe limits will be possible. Temperatures today will be cooler with cloud cover putting a cap on the diurnal heating. Overnight the waves cross the region with the surface trough moving east which shifts the deepest moisture into eastern Montana by Saturday morning. This trend continues into Saturday with cyclonic flow aloft over southern Montana but better low level forcing shifts into northeast Montana. Unsettled with showers and a couple of thunderstorms on Saturday and temperatures in the 70s which will be a welcome break from the heat. Precipitation amounts will be lighter due to the lack of forcing. borsum .LONG TERM...valid for Sun...Mon...Tue...Wed...Thu... Beginning Sunday we are still entering a wet and cool weather pattern, with temperatures across SE Montana in the 60s and 70s most of the week, and consistent showers and chances for weak thunderstorms almost every day. Upper ridging looks to break down late Sunday as an inverted shortwave trough looks to pass through the area. Showers are expected Sunday evening into Monday, with the heaviest amounts in far eastern Montana. There is good agreement for a significant rainfall event to occur during this time over much of eastern Montana, but much uncertainty lies in the rain amounts. Tuesday will present a brief dry period, before a larger, broad upper trough looks to cross over the Northwest CONUS. This will bring about chances for showers and weak thunderstorms every day through Friday, with another possibly significant rainfall event towards the end of the work week. However, much disagreement lies with this weather pattern, so little can be said about timing or location of rain at this time. Ridging looks to replace this pattern for the weekend, possibly bringing temperatures back to the upper 70s and little chances for rain. Vertz && .AVIATION... VFR will prevail for the rest of the night. After 1200 z, showers and weak thunderstorms will initiate over the Beartooth/Absaroka mountains and move northeast across the entire area, likely impacting all terminals throughout the day and into Friday night. Gusty and erratic winds are possible, as well as small hail and heavy rain, hence off-and-on MVFR to IFR conditions will be possible. Mountains will be obscured by the storms throughout the day. Low-level wind shear will continue to be possible at KMLS through the rest of the morning. Vertz && .PRELIMINARY POINT TEMP/POPS... Tdy Sat Sun Mon Tue Wed Thu ------------------------------------------------------- BIL 083 057/075 051/074 054/073 049/074 050/072 051/070 5/T 84/T 24/T 94/T 42/T 44/T 64/T LVM 080 050/075 046/072 046/069 041/071 043/069 043/069 8/T 84/T 27/T 95/T 54/T 55/T 64/T HDN 086 056/073 049/075 052/072 047/075 049/072 048/068 3/T 83/T 24/T 83/T 31/U 33/T 64/T MLS 085 058/069 049/070 055/069 048/071 051/069 050/065 3/T 86/T 51/E 85/T 32/T 43/T 54/T 4BQ 085 057/075 049/074 054/072 047/074 051/074 049/067 2/T 83/T 33/T 83/T 22/T 43/T 54/T BHK 082 054/068 047/068 051/069 047/070 049/069 049/066 1/B +6/T 71/E 86/T 32/T 53/T 54/T SHR 087 054/076 047/077 050/072 045/078 048/074 046/068 3/T 53/T 24/T 83/T 32/T 34/T 64/T && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$ weather.gov/billings