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Area Forecast Discussion
Issued by NWS Great Falls, MT
Issued by NWS Great Falls, MT
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404 FXUS65 KTFX 120350 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 950 PM MDT Sun Aug 11 2024 .UPDATE... && .SYNOPSIS... Near normal temperatures will be around through much of this week. Opportunities for showers and thunderstorms will be around most days this week, with Tuesday looking to be the best day for stronger thunderstorms across northeastern portions of the plains. && .UPDATE... No significant updates needed this evening. The cluster of thunderstorms that moved through the Cut Bank area earlier this evening will continue to weaken as it moves northeast along the Canadian border through midnight. Have kept a slight chance of showers and thunderstorms along the Northern Rocky Mountain Front through around midnight or so, as there are a few lingering storms west of the Continental Divide that may move over the Divide. Also added mention of overnight fog over the plains along the Canadian border where the showers and storms moved through and are currently moving over. -Coulston && .AVIATION... 11/18Z TAF Period The primary concern this TAF period will be for at least isolated showers and thunderstorms, primarily across Central and North- central Montana this afternoon and early evening. A few overnight showers and thunderstorms will be possible, especially late tonight along the Idaho border. Areas that see precipitation today and then clear out tonight will have an opportunity for a brief instance of fog early tomorrow morning. -AM Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PREV DISCUSSION... /ISSUED 127 PM MDT Sun Aug 11 2024/ Through Monday...A brief period of weak upper level ridging is building in for the afternoon and early evening across the Northern Rockies. Although this is the case, ample daytime heating will combine with lingering moisture to result in at least isolated showers and thunderstorms through the evening across Central and North-central Montana. Flow through the column will largely be unidirectional, with limited speed shear. Hence, showers and thunderstorms that do form today do not look to become organized in nature. A brief gusty wind threat appears to be the biggest concern this afternoon and evening with thunderstorms. Slightly warmer temperatures aloft will inhibit most, if not all chances for a shower or thunderstorm across Southwest Montana this afternoon and evening. As quickly as the upper level ridging builds in, southwesterly flow aloft builds in tonight ahead of an approaching Pacific Northwest trough. An embedded wave within this southwesterly flow will pass across the region late tonight, providing enough support for nocturnal showers and perhaps a thunderstorm or two, primarily across Southwest Montana near the Idaho border. Looking toward Monday, southwesterly flow persists, which will help raise temperatures to near average across the region. Additional showers and thunderstorms will be around Monday, initially across Southwest Montana and along the Rocky Mountain Front, shifting northeastward with time. Mixing looks to be a bit deeper Monday, which will give a slightly higher risk of gusty outflow winds from the stronger thunderstorms that do form. A bit of a more robust shortwave will approach the region late Monday night, yielding another opportunity for nocturnal showers and thunderstorms, mostly near the Idaho border. Tuesday... The aforementioned embedded wave within the persistent southwesterly flow aloft will bring an increased opportunity for showers and thunderstorms across the region Tuesday. The parameter space from a shear perspective looks favorable for stronger thunderstorms Tuesday, though uncertainty with respect to ongoing showers and thunderstorms early Tuesday leaves a question as to the thermodynamic favorability across the region. At this point, areas with the best chances for stronger thunderstorms are across eastern areas, where SPC has introduced a marginal risk for severe thunderstorms. Wednesday through the weekend... A bit of uncertainty begins to sneak in later in the week timing additional systems tracking eastward across the Northern Rockies. The takeaway at this point is for temperatures near normal through the late week into the weekend, with more or less daily low-end opportunities for showers and thunderstorms, though some of these chances may come overnight instead of the more typical afternoon and evening variety of showers and thunderstorms. -AM && .PRELIMINARY POINT TEMPS/POPS... GTF 56 86 55 83 / 0 10 20 50 CTB 52 82 51 81 / 20 20 20 20 HLN 55 88 57 84 / 0 20 20 60 BZN 49 87 51 81 / 0 20 20 60 WYS 41 77 43 71 / 10 40 30 80 DLN 49 82 50 76 / 20 20 10 60 HVR 57 88 57 89 / 10 10 30 30 LWT 50 83 53 81 / 0 10 20 50 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && $$ http://www.weather.gov/greatfalls