290 FXUS65 KBYZ 201301 AFDBYZ Area Forecast Discussion...Updated National Weather Service Billings MT 601 AM MST Sun Jan 20 2019 .UPDATE... Quick update to adjust pops and winds to current trends. Band of rain and snow will gradually shift to the western areas this morning, then move north through the day. The rest of the forecast remains on track and the previous forecast discussion is below. STP && .SHORT TERM...valid for Tdy and Mon... A warm front lifting north into the region was bringing rain and snow to central and western areas overnight. A band of precipitation is progged to settle over the western areas this morning, pushing north today, gradually decreasing as the warm front lifts north. In general, an inch or less of snow accumulation is possible over the lower elevations through today, with several inches of snow possible over the mountains. Winds will turn out of the north by Monday morning as a cold front drops into the area and an upper trough moves into the region. Snow chances will increase, especially over the mountains and foothills, gradually decreasing Monday night. As has been the case, there continues to be quite a bit of model uncertainty as there are differing solutions. The GFS has continued to keep split flow over the area and most of the energy to the south, while the ECMWF has been persistent in developing an upper low over southern Wyoming on Monday. The ECMWF solution brings better upslope and forcing to the area, leading to more precipitation, while the GFS solution confines most of the snow to the southern mountains and foothills. Given the uncertainty, have continued with a blended approach to the forecast. Will hold off on issuing any winter highlites at this time, but we will likely need winter weather advisories for portions of our foothills zones, where several inches of snow look possible. Highs will range from the 30s and 40s today, to the 20s and 30s on Monday. Lows will range from the teens in the far east to near 30 degrees along the western foothills tonight, with mainly teens for lows Monday night. STP .LONG TERM...valid for Tue...Wed...Thu...Fri...Sat... A period of strong downslope winds (w/ mainly dry wx) is expected Tuesday into Wednesday under NW flow aloft. Klondike chinooking will favor the Big Timber and Harlowton areas Tuesday and Tuesday night and would expect gusts to exceed 50 mph. Mid level flow will back/increase in advance of an approaching shortwave late Tuesday night and Wednesday, and it is during this time that strong gap winds are most likely at Livingston and Nye. Current guidance shows a likelihood of advisory level gusts (58+ mph). Anyone with travel plans along the western foothills Tuesday and Wednesday should be prepared for strong SW-W winds. Shortwave dropping out of the Gulf of Alaska will have a fairly deep moisture plume associated with it, and we will see potential for rain/snow showers to increase through the day on Wednesday, with snow over the western mountains of course. Wednesday night, a Canadian cold front associated with a shortwave emerging from the Arctic will arrive from the N-NE and enhance the potential for snowfall. Models show a great deal of spread with the strength of the secondary northern wave and how much we will will tap into the very cold air spilling into the northern plains to our east. Given the uncertainty, will keep forecast as a compromise...but looks like a decent chance of some snow along with colder temps Wednesday night into Thursday. Unsettled and highly uncertain northerly flow will continue through the end of the week. Another shortwave could bring the next round of pre-frontal downslope winds followed by post- frontal potential snowfall and cooling by Friday. Current model consensus suggests higher heights and drier/milder weather by next weekend, but not only is confidence in this scenario low, but the latest GFS/EC each show another Canadian front by Monday of next week. Overall, the weather pattern looks to remain active for the foreseeable future. Temps will be mildest in our west per the frequent downslope winds, and coldest in our east where surges of cold Canadian air are most likely. JKL && .AVIATION... VFR will prevail, but areas of rain and snow with local MVFR flight conditions can be expected across the lower elevations today and tonight. Mountains will be frequently obscured in snow. Sites KLVM and K3HT are most likely to see conditions drop below VFR today. An area of lower clouds with MVFR to IFR ceilings may impact eastern areas from KBHK to KMLS tonight as SE winds gust to 25 knots. JKL && .PRELIMINARY POINT TEMP/POPS... Tdy Mon Tue Wed Thu Fri Sat ------------------------------------------------------- BIL 043 028/034 019/035 028/040 018/029 020/039 028/043 3/O 26/S 20/U 15/O 54/S 22/J 11/B LVM 045 030/034 015/035 027/039 023/036 024/042 028/043 7/O 56/S 21/N 26/O 53/S 11/N 11/N HDN 044 025/035 018/036 022/040 016/029 016/039 023/043 3/O 16/S 40/B 16/O 54/S 33/J 22/J MLS 036 023/030 018/034 023/037 011/022 010/031 017/037 2/S 44/S 20/B 04/O 32/S 24/J 22/J 4BQ 041 025/032 018/033 021/038 014/022 010/033 017/037 2/O 16/S 40/B 14/O 43/S 24/J 32/J BHK 035 018/026 015/032 020/035 007/016 006/029 013/034 1/E 43/S 30/B 02/S 22/S 24/J 32/J SHR 044 023/034 016/035 017/040 016/028 013/038 020/041 3/S 28/S 60/B 15/O 54/S 33/J 32/J && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$ weather.gov/billings