340 FXUS65 KBYZ 100229 AFDBYZ Area Forecast Discussion...Updated National Weather Service Billings MT 829 PM MDT Tue Oct 9 2018 .UPDATE... We lowered PoP's across the area for tonight as radar and any ground truth we have collected suggests only scattered pockets of light rain/snow over the region. This seems to be mainly along and near the foothills and mountains where upslope and weak frontogenetic ascent is occurring. So although we cannot completely rule it out with a large trough moving over the Rockies, the chance of measurable precipitation over the plains seems less now. We also added fog to many locations overnight based on webcams and reported dewpoint depressions. BT && .SHORT TERM...valid for Wed and Thu... Broad upper trough dropping into Idaho with low level easterly flow for upslope. Models drop the low into northern Utah late tonight and fill it as it works across southern Wyoming on Wednesday. This process will generate weak ascent with low level upslope and overrunning. Western locations, and the foothills in particular, will be hit the hardest with ascent and periods of light snow. Lack of strong ascent should keep snow rates low. Looking at 2-4 inches along the foothills from tonight through Wednesday night. Forcing weakens Wednesday afternoon and night, but does not entirely go away, so lingered high PoPs through Wednesday night, A northern stream trough will drop southeast and move across Montana on Thursday. This process will drag some drier air into southern Montana and northern Wyoming, bringing an end to the PoPs. Highs Wednesday will be held down in extensive cloud cover and moderate cold air advection. As the low level upslope subsides on Thursday, this will allow for temperatures to warm a bit. TWH .LONG TERM...valid for Fri...Sat...Sun...Mon...Tue... Pre-frontal conditions on Friday will bring gusty downslope winds along with a bit warmer temperatures to the area. A clipper system dropping out of Canada will bring increasing chances for rain and snow showers along with cooler temperatures and gusty northwest winds for Saturday into Sunday. Best precipitation chances will be found along the mountains and foothills. With cool temperatures aloft, we could see some light snow accumulations. Drier conditions then look possible for Sunday night into Monday, before another clipper system is progged to move through the area Monday into Tuesday. While models are out of sync with the timing of the clipper, there is consensus with the general idea with cooler temperatures and precipitation chances continuing. Highs will range from the 50s to 60s on Friday, to the 30s and 40s on the weekend, with 40s and 50s early next week. Low temperatures will range from the 20s to 30s most nights and mornings. STP && .AVIATION... Conditions will range from MVFR to LIFR tonight into Wednesday in areas of rain and snow. The lowest conditions will be around KLVM and near the mountains. Conditions will improve to VFR in most areas Wed. afternoon, however, MVFR will persist W of KBIL. Expect areas of mountain obscuration through the period. Arthur && .PRELIMINARY POINT TEMP/POPS... Wed Thu Fri Sat Sun Mon Tue ----------------------------------------------------------- BIL 031/039 028/043 030/061 035/041 025/044 030/054 036/057 34/O 32/S 00/N 33/W 21/B 01/B 21/B LVM 028/037 024/043 029/059 033/039 024/044 027/051 033/054 76/O 43/S 00/N 44/W 21/B 01/B 31/B HDN 031/041 029/043 028/061 035/042 027/044 029/054 036/056 32/O 22/S 00/B 33/W 22/W 01/B 21/B MLS 029/041 026/043 028/058 035/042 023/043 028/052 035/053 32/S 11/B 00/B 12/W 21/B 02/W 21/B 4BQ 029/038 024/043 027/058 035/041 022/040 026/052 035/052 33/S 11/E 00/U 12/W 21/B 01/B 31/B BHK 027/038 021/041 025/053 033/039 021/038 024/048 032/049 43/S 01/B 00/B 12/W 21/B 02/W 22/W SHR 029/038 027/042 026/064 033/040 023/040 023/052 032/053 34/O 32/O 10/U 34/W 22/J 01/B 22/W && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$ weather.gov/billings