162 FXUS65 KTFX 182107 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 207 PM MST Fri Jan 18 2019 .SYNOPSIS... Gusty west to southwest winds develop along the east slopes of the Rockies overnight into Saturday, pushing temperatures back above seasonal averages for most areas by Saturday afternoon. Strong winds along the Rocky mountain front could create localized blowing and drifting snow early Saturday. Areas of rain and snow develop on Sunday, changing to snow overnight Sunday into Monday. && .DISCUSSION... Clouds are thinning across the forecast area this afternoon, except over mountain areas where lower clouds could persist into evening. Surface winds are already beginning to increase along the Rocky Mountain Front, producing warmer temperatures. This trend will continue on Saturday as a lee-side trough strengths and 700mb winds pick up to 50-60 kts. Areas of drifting and blowing snow become likely overnight through early Saturday. The combination of snow scouring and rising temperatures will mitigate blowing snow concerns by Saturday afternoon. The strongest winds are expected to remain confined close to the Rocky Mountain Front from around Babb through Heart Butte. A high wind watch has been posted, although there is not high confidence that wind gusts will reach the 75 mph warning criteria for this area. Will continue to evaluate the forecast as higher resolution model data becomes available before deciding if a high wind warning is warranted. Mild temperatures persist overnight Saturday into Sunday. The next round or valley rain and mountain snow will begin to develop across Southwest Montana early Sunday. A band of rain and snow lifts north with a warm front through the day on Sunday. Although light rain is expected at lower elevations, accumulating snow over the mountain areas could exceed 6 inches and warrant new winter weather headlines. The surface low responsible for this precipitation tracks through central Montana. As such, once the wave passes, winds turn northwesterly, temperatures fall, and rain changes to snow. PN Sunday night through Wednesday...Latest model guidance, including the GFS and Euro, remains in good agreement during this period. Precipitation, mainly in the form of snow, becomes more widespread over our CWA Sunday night into Monday as a Pacific shortwave trough approaches Sunday night and then crosses our region on Monday. POPs then wane Monday night as the shortwave trough presses farther east and high pressure aloft builds from the west. Snow totals through Monday night should generally reach 1-5" for the plains and valleys, while the mountains look to receive about 5-12". On Tuesday, lingering snow should be confined to our mountains due to a combination of upslope flow along west through north-facing aspects, high pressure aloft overhead, and downslope breezes affecting the plains and valleys. Another shortwave disturbance is poised to cross the CWA from northwest to southeast on Wednesday, resulting in another round of widespread precipitation. Near or slightly- above normal temperatures are expected through Wednesday, with Wednesday now forecast to be the warmest day during this period. Thursday through Friday...Latest forecast incorporates NBM guidance due to discrepancies between 12Z/Fri runs of the Canadian, Euro, and GFS models. Thus, primarily dry conditions and above-normal temperatures are featured in the forecast as high pressure ridging aloft builds from the west. Even though it is an outlier, it is worth noting the often reliable Euro is not as aggressive with the eastward progression of this ridge. Instead, the Euro suggests multiple snow-producing shortwave troughs embedded in cyclonic flow aloft and a colder air mass will reside over our CWA. Thus, forecast confidence is relatively-low and this period will continue to be monitored closely. - Jaszka && .AVIATION... Updated 1740Z. VFR conditions prevail all terminals. However, MVFR cigs persist with lingering light snow at KHVR through around 20Z. Overall trend is for thinning cloud cover. Surface winds remain generally light through much of today but increase from the SW late this afternoon and evening at KCTB and KGTF. && .PRELIMINARY POINT TEMPS/POPS... GTF 26 49 31 42 / 0 0 10 50 CTB 20 47 25 40 / 0 0 0 40 HLN 20 43 26 41 / 0 10 10 60 BZN 18 40 26 42 / 10 20 20 50 WEY 13 28 18 33 / 70 80 70 70 DLN 21 39 28 42 / 10 20 20 30 HVR 8 42 21 41 / 0 0 0 20 LWT 21 47 27 42 / 0 0 10 40 && .TFX WATCHES/WARNINGS/ADVISORIES... High Wind Watch from Saturday morning through Saturday evening Northern Rocky Mountain Front...Southern Rocky Mountain Front. && $$ http://www.weather.gov/greatfalls