973 FXUS65 KTFX 282014 AFDTFXArea Forecast Discussion National Weather Service Great Falls MT 214 PM MDT Sun Sep 28 2025
.KEY MESSAGES...
- Isolated showers and thunderstorms south of I-90 tonight.
- Coverage of precipitation increases Monday and Tuesday, with the best chances along the Continental Divide.
- A cool down in temperatures for the second half of the week.
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.DISCUSSION...
- Meteorological Overview:
The ridge in place will keep most of the region dry today. However, increasing moisture and ascent aloft towards the MT/ID border will produce some isolated showers and thunderstorms later this evening. Monday, with more influence under the trough propagating eastwards, a small embedded shortwave will increases coverage of afternoon/evening showers and thunderstorms. Best chances for precipitation will be along the Continental Divide, but there will be some isolated showers/thunderstorms across the plains. Tuesday, a cold front passing through will bring another round of showers and thunderstorms along with an increase in winds in Southwest MT.
The trough will continue to bring sporadic chances for precipitation through the rest of the week. This trough will also help bring in cooler air to bring back fall-like temperatures. Cooler conditions look to trend still heading into next weekend. Though there remains uncertainty in how much precipitation and how cool it gets with the next weekend`s system.
- Forecast Confidence & Scenarios:
For thunderstorms Monday, low CAPE and shear will keep thunderstorms on the weaker side overall. A mid/low level jet Monday will allow for the isolated potential for a few stronger wind gusts with showers/thunderstorms (40-50 mph). Precipitation with showers/storms will stay light overall (~.10") but a few heavier showers can create locally higher amounts.
For the system next weekend, there is uncertainty in the models of the evolution of this trough and how much colder air it brings. This will affect how much precipitation we get and snow levels. Right now, there`s a 20-40% chance for 1" of snow at the higher peaks Friday through Sunday.- Wilson
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.AVIATION... 28/18Z TAF Period.
VFR conditions prevail across the area through the period under a generally dry south to southwest flow aloft. Clear skies persist through tonight across most of the area while some mid to higher level clouds spread north into southwest MT this evening. There is a low (less than 20%) chance of a shower drifting north from ID into the KWYS vicinity. Northerly surface winds across the plains will decrease and turn to the east or southeast this evening with southerly surface winds developing across much of the area on Monday. Hoenisch
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.PRELIMINARY POINT TEMPS/POPS... GTF 46 86 55 79 / 0 0 10 20 CTB 41 81 49 72 / 0 0 10 20 HLN 49 83 53 76 / 0 10 30 40 BZN 47 80 49 74 / 0 20 10 30 WYS 36 68 39 60 / 20 30 20 70 DLN 45 77 48 69 / 20 10 40 40 HVR 46 85 53 79 / 0 0 0 0 LWT 49 83 53 79 / 0 10 0 20
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.TFX WATCHES/WARNINGS/ADVISORIES... None. &&
$$ http://www.weather.gov/greatfalls
NWS TFX Office Area Forecast Discussion