Area Forecast Discussion
Issued by NWS Great Falls, MT
Issued by NWS Great Falls, MT
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
441 FXUS65 KTFX 192048 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 148 PM MST Wed Nov 19 2025 .KEY MESSAGES... - After lingering showers diminish this afternoon, patchy fog looks to develop heading into Thursday morning. - Another period of breezy winds across the plains develops Friday into Saturday. - Confidence increasing in another at least breezy period Monday ahead of a trend cooler next week. && .DISCUSSION... - Meteorological Overview: Weak troughing associated with a more potent wave further north in Canada and an upper low in CA will pass across the Northern Rockies through the remainder of the afternoon before exiting eastward tonight. Forcing for light rain and snow will wane through the late afternoon and evening. Additional snow accumulations look light and focused in the mountains. As skies attempt to clear tonight, at least patchy fog will develop. Areas most favored for fog will be in Southwest Montana valleys in addition any other areas that see more than just a trace of rain or snow through the remainder of the afternoon and early evening. Brief shortwave ridging moves in for Thursday, allowing for a dry day with temperatures trending milder again. Another splitting trough then moves in across the Pacific NW late Thursday into Friday, with the main upper disturbance shifting well south of the region, with a weaker wave staying further north. A largely zonal flow develops as a result, which will result in at least light precipitation along the Continental Divide north of Lincoln Friday into Saturday. Additionally, breezy winds look to return over the plains Friday (Locally stronger along the Rocky Mountain Front), lingering through the day Saturday. The largely zonal flow continues into early next week, with increasing confidence in a quick moving disturbance moving across the region Monday into Tuesday. Another period of at least breezy winds looks to accompany this system, with areas north of Lincoln along the Continental Divide once again favored for precipitation. A northwesterly flow aloft look to develop in wake of the Monday/Tuesday system, which would strongly favor a cooling trend, with at least low-end probabilities for snow. -AM - Forecast Confidence & Scenarios: Winds Friday into Saturday: Although cross barrier flow does not look overly impressive from a magnitude perspective, the combination of strong ridgetop stability and a building pressure gradient will help to translate these winds to the surface Friday into Saturday. The probability for a 55 mph gust in Cut Bank is roughly 50% late Friday into Saturday. Further west in Browning the probability for a 70 mph gust is around 40%. Given the lower confidence in stout cross barrier flow and reliance on a strong pressure gradient developing, I have opted to hold off from any High Wind Watches at this time for Friday into Friday night. Trends will continue to be monitored for changes in confidence for higher impact wind over this timeframe. Winds Monday: Ensemble guidance is beginning to key in on another at least breezy period across the region Monday. Although this is the case, the range of scenarios remains rather high. The 25th-75th percentile spread for a max wind gust at Cut Bank is roughly 25 mph (25th percentile is roughly 40 mph and the 75th percentile is roughly 65 mph). All this to say: Confidence is increasing in a breezy period Monday, with confidence in specific magnitudes remaining low. Cooldown Next Week: After the period of breezy winds Monday, a northwesterly flow aloft will ensue. Cooler air looks to move in as a result, with daytime highs falling a touch below average by Wednesday. Although the probability for precipitation increases toward the middle of next week, an overly wet scenario is not favored. The probability for 3 inches of snow over the 48 hours prior to Thanksgiving morning is less than 10% at lower elevations. -AM && .AVIATION... 19/18Z TAF Period The initial concern this TAF period will be for a mix rain and snow showers through the afternoon and early evening, primarily across Central and Southwest Montana. Instances of low clouds will continue this afternoon across Central and Southwest Montana, especially near precipitation. Patchy fog looks to develop tonight, with greatest confidence in Southwest Montana valleys. That said, confidence was too low to warrant mention of fog in TAFs at this time. Mountains will be obscured at times this TAF period. -AM && .PRELIMINARY POINT TEMPS/POPS... GTF 26 52 31 53 / 10 0 0 0 CTB 21 49 27 49 / 0 0 0 0 HLN 27 48 26 50 / 20 0 0 0 BZN 24 49 24 51 / 10 0 0 0 WYS 25 45 17 44 / 20 10 0 0 DLN 26 46 25 49 / 10 0 0 0 HVR 20 45 24 53 / 0 0 0 0 LWT 24 52 29 55 / 10 0 0 0 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && $$ http://www.weather.gov/greatfalls