Area Forecast Discussion
Issued by NWS Great Falls, MT
Issued by NWS Great Falls, MT
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937 FXUS65 KTFX 180019 CCA AFDTFX Area Forecast Discussion... National Weather Service Great Falls MT 619 PM MDT Fri May 17 2024 ...UPDATED AVIATION SECTION... .SYNOPSIS... Strong and gusty winds behind a cold front will continue into this evening across much of North Central, Central, and Southwest Montana. Scattered showers with a few thunderstorms will also diminish through midnight. Gusty, but not quite as strong, winds will return to the region for Saturday, with a chance for mainly mountain showers. A disturbance will then bring more widespread shower activity to the area for Sunday, with cooling temperatures and a chance for thunderstorms as well. && .DISCUSSION... Today and Tonight... Scattered showers and thunderstorms are already underway across north-central and central Montana. The chance for thunderstorms will continue through the rest of the evening, diminishing by 9 PM for most locations and as late as midnight for locations along the hi-line east of Havre. The risk for any one thunderstorm turning severe is generally low, however, some indications remain in the model soundings that downbursts from decaying thunderstorms could throw out an isolated 60 mph gust. With regards to hail, the dry layer near the surface persists in this round of updated model soundings so while pea- sized hail may be possible in stronger storms, nothing beyond that is expected. The wild card of the evening is that convective models have been showing a marginal potential for cold air funnels developing along the hi-line. While not expected to be a significant concern this afternoon, a cold air funnel or two cannot be ruled out. Otherwise, for most of the region, gusty winds will continue through the rest of the day with the strongest gusts tapering off after sunset. Some gusty winds will continue through the night for locations in central Montana including Judith Basin, Fergus, and Meagher counties. -thor This weekend... Large scale upper troughing will remain in place across SW Canada and the far northern portions of the NW CONUS this weekend, resulting in largely zonal flow aloft, with shortwaves pivoting across the region at times. The end result is for unsettled conditions remaining. Temperatures will be on the cooler side, with opportunities for showers and perhaps a few thunderstorms. Sunday looks to be the day more favored for showers and thunderstorms, as a robust shortwave pivots through the broad troughing. Confidence in timing is not yet high, but the chance for a tenth of an inch of precipitation Sunday into Sunday night is largely greater than 50% across the region. Next Week... Ensembles favor a continuation of unsettled conditions heading into next week as large scale troughing remains in place across much of the Pacific NW and Northern Rockies. Although confidence is high that unsettled conditions will remain, specifics with respect to timing and magnitude of any precipitation is murky at best at this point. -AM && .AVIATION... 18/00Z TAF Period Scattered shower/thunderstorm activity, most numerous over Central/North-central MT, will diminish through 18/06Z, though at least some shower activity will persist into the overnight hours along the Continental Divide and the plains. Gusty west to northwesterly winds will also begin to diminish with the loss of diurnal heating, but brief gusts up to and exceeding 50 kts can be expected, particularly during showers/storms through 18/04Z. Breezy conditions continue overnight tonight and Saturday but will generally be less than 30 kts. Mountain wave turbulence and instances of low level wind shear will be present through 18/12Z. - RCG Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PRELIMINARY POINT TEMPS/POPS... GTF 39 62 39 55 / 40 10 10 80 CTB 34 59 33 54 / 50 20 10 80 HLN 39 66 42 57 / 10 0 10 70 BZN 29 65 37 56 / 10 0 10 70 WYS 25 57 34 53 / 10 0 10 40 DLN 29 65 37 56 / 0 0 10 40 HVR 38 63 38 60 / 80 10 0 50 LWT 35 59 37 52 / 30 0 20 70 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && $$ http://www.weather.gov/greatfalls