FXUS65 KTFX 200603 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 1203 AM MDT Wed May 20 2026 .KEY MESSAGES... - A cold front brings a round of scattered to numerous showers and embedded thunderstorms today, mostly over central and north- central Montana. - This activity will transition to general areas of rain and mountain snow as it moves into southwest Montana tonight into Thursday morning. - The precipitation decreases in coverage by Thursday afternoon,with much warmer and drier conditions moving in for most if not all of the holiday weekend. - An approaching cold front will bring breezy to windy conditions and increased shower and thunderstorm activity Monday into Tuesday followed by a period of cooler temperatures, mountain snow, and lower elevation rain. && .DISCUSSION... - Meteorological Overview: Scattered showers over the plains have continued well into the evening hours despite the loss of diurnal heating. The biggest concern with these showers have been localized gusty winds, with a top wind gust of 50 mph reported near the Big Sandy area. Northwesterly flow aloft will maintain these isolated showers through around 1 or 2 AM. Otherwise, the focus shifts to a trough and attendant cold front that will dive southeastward and initiate a round of scattered to numerous showers and embedded thunderstorms over north-central and central MT later this morning and afternoon. Cooler surface temperatures with ML CAPE struggling to reach a couple hundred J/kg will reduce the overall impact from this activity, though isolated instances gusty winds over 40 mph, small hail/graupel, and productive downpours will be present with the stronger cores. The forcing from the trough pushes this activity into southwest MT tonight into Thursday morning, with H700 temperatures falling to around -5C and supporting accumulating snow down to 6000 ft. Snow impacts for Thursday morning look to the be greatest over the higher terrain of Madison and Gallatin counties and will mostly be in the form of cold and wet outdoor conditions. Temperatures will run a few degrees below average on Thursday before weak ridging aloft warms things up heading into the weekend. Westerly flow aloft will be strong enough to mix gusty winds to the surface Sunday and Monday while temperatures warm well into the 70s and 80s. The next trough and cold front will usher in a more unstable southwesterly flow aloft early next week for increased shower and thunderstorm activity and more breezy to windy conditions, windiest over southwest MT. Some storms may become strong to severe depending on the troughs's timing, strength and whether it undergoes shearing or splitting. Note that closed lows such as this one often run a little slower than model guidance. This may result in hotter and drier weather on Monday if the cold front runs late and arrives on Tuesday. There will be at least a period of cooler temperatures and more widespread precipitation/mountain snow on the backside of this system heading towards mid-week, particularly if the main circulation stays close enough to exert a stronger influence over the Northern Rockies. - RCG - Forecast Confidence & Scenarios: Today's showers and thunderstorms will transition to areas of rain and mountain snow tonight into Thursday morning... Scattered to numerous showers and embedded thunderstorms develop over central and north-centrtal MT by the late morning hours. This activity will bring more productive rainfall than those of the last couple of days. Although severe weather is not expected with the cooler temperatures behind the front, there may be localized instances of gusty winds over 40 mph, small hail or graupel, and heavy downpours over a quarter inch with the stronger cores. This activity will expand in coverage and become more stratiform as it slides southward into southwest MT tonight into Thursday morning. H700 temperatures falling to around -4 to -7C combined with lingering convective processes may drop snow levels as low as 5000 ft at times, though accumulating snow looks to primarily be confined to areas above 6000 to 6500 ft and even higher. Snowfall amounts look to be most significant over the northern portions of the Madison/Gallatin ranges where the probabilities for 3 inches of snow or more are currently running above 70% tonight through Thursday morning. Other mountain areas of the southwest, along the Continental Divide, and over the central island ranges will generally see trace amounts up to around an inch or two on the high end. Overall, cold and wet outdoor recreation will be the primary impact with this system. Total rainfall/liquid equivalent amounts will generally range between a tenth to a quarter inch for most lower elevation locations with a sharp decreasing gradient to just a few hundreths or so along the Hi-Line and the drier southwest valleys along and west of I15. Of course rainfall amounts in excess of a half inch will be more common for areas over and near higher terrain. Precipitation diminishes and becomes more scattered in nature by Thursday afternoon. - RCG && .AVIATION... 20/06z TAF Period An upper level disturbance moving over the Northern Rockies will spread precipitation from north to south across North Central through Southwest Montana, with VFR CIGS falling to MVFR/low-VFR between 15-21z Wednesday and then persisting through the remainder of the 2006/2106 TAF period. While terminals will predominately see light rain or rain showers the KGTF, KLWT, and KHLN terminals have the best opportunity for an isolated thunderstorms; however, even these chances were to low to mention. Mountain obscuration will begin to increase between 09-15z Wednesday. - Moldan && .PRELIMINARY POINT TEMPS/POPS... GTF 56 36 60 37 / 90 60 20 0 CTB 54 33 62 37 / 70 20 10 0 HLN 63 36 61 37 / 60 90 20 0 BZN 61 33 56 31 / 30 90 50 0 WYS 56 28 51 23 / 20 90 40 0 DLN 61 33 58 32 / 10 80 30 0 HVR 61 34 65 35 / 50 10 20 0 LWT 56 33 55 33 / 80 60 40 0 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && $$ http://www.weather.gov/greatfalls