Area Forecast Discussion
Issued by NWS Great Falls, MT
Issued by NWS Great Falls, MT
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991 FXUS65 KTFX 302357 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 557 PM MDT Sun Jun 30 2024 ...Aviation Section Updated... .SYNOPSIS... Strong to severe thunderstorms will be around across eastern portions of Southwest through Central Montana this afternoon and evening. Thereafter, the upcoming week looks to be on the cooler side of average, with daily opportunities for showers and thunderstorms through July 4th. Looking toward this weekend, warmer and drier conditions are favored. && .DISCUSSION... The rest of today and tonight... The leading wave within an approaching upper level trough is passing across the region this afternoon. This wave has helped initiate showers and thunderstorms near Monida Pass that will shift northeastward through the evening. Relatively deep inverted-V soundings, modest instability, and long straight hodographs will foster a strong wind gust and hail threat, though the former is the main concern today. These showers and thunderstorms exit eastern portions of Central Montana this evening. Although the most favorable area for ascent will exit eastward tonight, the broad upper trough across the region will still allow for showers and thunderstorms to develop across Southwest Montana tonight, with impacts being much more limited. Monday... The broad troughing will remain in place across the northern Rockies, allowing for scattered showers and thunderstorms, mainly in the afternoon and evening. At this point, these thunderstorms look to be more of a run-of-the-mill variety. -AM Tuesday through the 4th of July...Expect a slow cooling trend for temperatures during this period, with the 4th of July looking like the coolest day for most areas. The airmass will remain unstable, with daily chances for showers/thunderstorms, especially for areas north of I-90 from Butte to Bozeman. At this time, it looks like the showers/storms will exit much of the CWA by late in the afternoon on July 4th, resulting in mostly dry conditions for the 4th of July evening hours. Overall, the threat for any severe storms early next week looks to be less than 10 percent. Friday through Sunday...The GFS and EC differ in terms of how strong an upper level trof will be over MT for next weekend. Right now there is only about a 20 percent chance from the cluster analysis that the GFS is right. Thus, I will continue to use the warmer and drier NBM solution for next weekend, as there is an 80 percent chance for this solution to pan out. Brusda && .AVIATION... 01/00Z TAF Period VFR conditions will prevail across all terminals excluding the KBZN and KEKS terminals during this TAF period. For the next several hours showers and thunderstorms will affect the KBZN and KEKS terminals. At the KBZN terminal some of the showers will reduce visibility to MVFR levels at times. Showers will affect the KHLN terminal for the next two hours. Monday morning showers and thunderstorms will affect the KBZN, KEKS, and KWYS terminals through at least mid morning. They have the potential (30% chance) to continue through the end of the TAF period at the KWYS and KEKS terminals. The showers and thunderstorms have a 30% chance to reduce visibility and ceilings to MVFR levels through the end of the TAF period at the KWYS and KEKS terminals. For the KCTB and KHVR terminals there is a 30 - 50% chance for showers and thunderstorms Monday afternoon through at least the end of the TAF period. Monday afternoon through the end of the TAF period there is a 20% chance for showers and thunderstorms at the KBZN, KHLN, KGTF, and KLWT terminals. During any thunderstorms erratic, gusty winds and small hail are possible. Winds across the KHLN, KGTF, KCTB, KHVR, and KLWT terminals will increase beginning Monday morning and continuing through at least the end of the TAF period. Intermittent mountain obscuration is expected across Southwestern Montana during the duration of this TAF period. -IG Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PRELIMINARY POINT TEMPS/POPS... GTF 53 76 52 75 / 30 30 40 50 CTB 51 71 50 73 / 10 60 30 60 HLN 54 79 54 81 / 50 30 30 30 BZN 50 74 47 76 / 60 60 60 20 WYS 44 65 37 67 / 50 80 80 20 DLN 48 71 43 73 / 60 60 40 0 HVR 55 76 54 77 / 30 40 30 70 LWT 50 72 48 71 / 80 20 20 70 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && $$ http://www.weather.gov/greatfalls