296 FXUS65 KTFX 061147 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 545 AM MDT Thu Sep 6 2018 ...UPDATED AVIATION SECTION... .SYNOPSIS... An unstable southwest flow aloft will bring mainly afternoon and evening showers and thunderstorms with gusty erratic winds through the end of the week. Temperatures will warm to around 10 degrees above normal by Friday, but a Pacific cold front will cool temperatures closer to normal on Saturday with gusty westerly winds. && .DISCUSSION... Today through Saturday...Disturbances in the moist and unstable southwest flow aloft will spread scattered showers and thunderstorms northeast over the forecast mainly during the afternoon and evening hours through Saturday. Warmer than normal temperatures with dry conditions near the surface will cause some of these storms to have gusty erratic winds today and Friday. A frontal boundary will move through the forecast area Friday and Friday night, bringing gusty westerly winds to the area on Saturday, as temperatures cool back closer to normal. The forecast mid level winds during this time period are not quite as strong as what previous forecasts were indicating, so gusts along the Rocky Mountain Front may approach 50 mph, but high wind highlights are not expected at this time. Coulston Saturday night through Thursday...Moist west to southwest flow over the region into Sunday, perhaps bringing an isolated afternoon shower or two across Central Montana. Models remain in solid agreement with a continued west-southwest flow through next week. A low pressure system in the Pacific Northwest stagnates offshore and keeps this influence over Montana through the week. With good jet support expect afternoon winds to pick up out of the west, with strongest winds along the Northern Rocky Mountain Front. This system looks to remain stuck in place in one form or another, keeping increased chances for cooler weather and precipitation, especially along the Continental Divide. Temperatures remain in the 70s Sunday, 80s Monday, then fall generally into the 60s Tuesday and beyond. && .AVIATION... Updated 1145Z. VFR conditions will continue through at least 12Z Friday. A disturbance in the unstable southwest flow aloft will bring increasing mid and high level cloudiness to the area through 18Z. Scattered showers and thunderstorms will then spread northeast over the area south of the Hi-Line through 00Z. The main threat from these storms will be erratic gusts of up to 40 mph at times, but winds will be light otherwise. Storms will then decrease from the west from 01Z through 06Z. Overall, smoke from fires to the southwest may gradually reduce visibility through the period, but significant reductions are not anticipated at least through this period. Coulston && .FIRE WEATHER... Warm temperatures and low relative humidity near the surface today into this evening may cause some thunderstorms to be high- based and/or dry with gusty erratic winds. This will increase the potential for lightning strikes to cause new ignitions with rapid spread due to the wind. However, there will likely be a mix of wet and dry thunderstorms to limit any new fire spread. Will therefore highlight this threat in the Fire Weather Forecast, but am not anticipating a need for a watch or warning. Gusty west winds will likely also develop in the wake of a cold front Saturday afternoon and evening, but somewhat low relative humidities will recover as winds increase. Will monitor this situation for potential highlights. Coulston && .PRELIMINARY POINT TEMPS/POPS... GTF 83 52 88 57 / 20 20 0 20 CTB 80 48 85 53 / 0 0 10 10 HLN 85 52 87 55 / 30 30 10 10 BZN 85 48 85 50 / 20 30 0 10 WEY 77 37 76 38 / 10 10 10 10 DLN 83 46 83 49 / 30 30 0 0 HVR 83 50 87 54 / 0 0 10 20 LWT 81 51 85 54 / 10 20 10 10 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && $$ http://www.weather.gov/greatfalls