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Area Forecast Discussion
Issued by NWS Great Falls, MT
Issued by NWS Great Falls, MT
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197 FXUS65 KTFX 201048 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 448 AM MDT Sat Jul 20 2024 ...Aviation Section Updated... .SYNOPSIS... For today, there is an isolated chance of showers and thunderstorms across higher terrain. Otherwise, dry conditions and well above normal temperatures are expected to continue through the middle of next week. && .DISCUSSION... Today through Monday... The upper level ridge will remain over the Northern Rockies through the weekend keeping temperatures well above normal across the region. Winds will generally remain less than 15 mph with an occasional gust up to 25 mph. While most locations will remain dry through the weekend, isolated to scattered showers and thunderstorms will be possible during the afternoon and evening hours, most notably over higher terrain. The primary threat from any shower or thunderstorm will be gusty and erratic winds given the model inverted-v soundings. Tuesday through next Saturday... Heading towards the middle of next week, an upper level trough sets up off the coast of British Columbia. As it tries to push to the east, it compresses the ridge into a more positive tilt with the ridge axis stretching into eastern Montana/southern Saskatchewan. This will lead to significant warm air advection over Montana and a heatwave lasting Tuesday through Thursday with widespread highs in the upper 90s to low 100s across the lower elevations of the state. By Thursday the trough starts to shove the ridge to the east with ensemble clusters favoring the breakdown of the ridge towards the end of next week. There is relatively good agreement amongst the clusters that the trough will be positioned over southern British Columbia by Thursday afternoon. From there, disagreement starts to creep in as to how quickly the trough will be able to push east. A couple of the clusters have the trough making it to southern Alberta by Friday afternoon while other clusters have the trough hanging back around southern BC. By Saturday, there is a general agreement that the ridge will break down to some degree. What will be interesting to watch is, compared to the model runs 24 hours ago, more clusters are agreeing on the trough digging further south over the western CONUS. Depending how the trough eventually sets up, at the very least, central Montana can expect temporary relief by next weekend in which temperatures will be brought back down closer to normal for this time of year. -thor && .AVIATION... 20/12Z TAF Period VFR conditions will prevail through the 2012/2112 TAF period; however, slantwise visibility reductions due to smoke/haze from wildfires burning across the Western US and Canada will be common across Southwest through North Central Montana. Additionally, afternoon through evening cumulus development will once again occur over the higher terrain on Saturday, with an isolated shower or thunderstorm also being possible over these same areas and along/east of a KEKS, to KBZN, to KLWT, to KHVR line. With the chance for any one shower or storm being below 20% across the aforementioned terminals this afternoon I have withheld mention at this time. - Moldan Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .FIRE WEATHER... Fire weather concerns will remain throughout next week with hot and dry conditions expected to persist across central Montana. The limiting factor that will keep many locations from reaching the critical fire weather threshold will be the wind. Generally light winds are expected to persist through the weekend and into the middle of next week. Some isolated gusts up to 25 mph are possible during the middle of the afternoon with peak mixing, however, for the most part gusts will remain under 15 mph for much of central Montana. Looking ahead, the next concern will be how winds behave when the ridge starts to break down. The level of concern will be hinged on how the ridge ultimately breaks down which is still a point of disagreement for the long-range models. Thus, it is something to be watched but no specifics are available at this time. Otherwise, the over-arching concern for fire weather is that we are now getting into the part of the summer where conditions have been hot and dry long enough that lighter winds may still prove problematic for fire suppression. While no products are planned at this point in time, the upcoming week will be watched closely for changes in expected conditions. -thor && .PRELIMINARY POINT TEMPS/POPS... GTF 92 61 92 61 / 0 0 0 0 CTB 92 58 91 58 / 20 0 0 0 HLN 96 62 95 62 / 10 0 0 0 BZN 92 55 91 55 / 20 0 0 0 WYS 82 44 82 42 / 20 10 10 0 DLN 88 52 90 52 / 20 0 0 0 HVR 94 62 94 62 / 20 10 0 0 LWT 87 57 87 57 / 20 10 0 0 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && $$ http://www.weather.gov/greatfalls