Area Forecast Discussion
Issued by NWS Great Falls, MT
Issued by NWS Great Falls, MT
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946 FXUS65 KTFX 301522 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 922 AM MDT Sun Jun 30 2024 .SYNOPSIS... Showers and thunderstorms will move from west to east across the area today. Some storms could be severe this afternoon or early this evening. Overall, a cooling trend will be occur with afternoon temperatures over the next few days, with the 4th of July likely being the coolest day of the week for most areas. Expect scattered showers or thunderstorms most days through the 4th of July afternoon, with clearing skies on the evening of the 4th of July. && .UPDATE... No significant tweaks were needed with the update this morning. Confidence is increasing that there will be strong to severe thunderstorms across eastern portions of Southwest through Central Montana this afternoon and early evening. Satellite and radar this morning are still showing a few showers across Southwest Montana, but with clearing skies moving in from the south, this will set the stage for increasing instability heading into the afternoon. Forecast soundings for this afternoon across Southwest into Central MT show long straight hodographs, with relatively deep inverted-V profiles. This suggests both strong wind gusts and hail will be a concern with the most robust storms, though stronger wind gusts appear to the most prolific threat at this time. These look to initially form across Southwest MT early to mid afternoon, spreading northeastward with time through the evening. Those recreating today are urged to be weather aware and have a plan for thunderstorms. -AM && .AVIATION... 30/12Z TAF Period Aside from a few isolated SHRA this morning, expect VFR conditions to continue through 18z. Instability increases this morning and afternoon, especially across SW MT, which will result in widely scattered to widespread showers and thunderstorms, some of which may bring hail and gusty winds in addition to IFR conditions. TSRA and SHRA move eastward after sunset. Ludwig Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PREV DISCUSSION... /ISSUED 550 AM MDT Sun Jun 30 2024/ Today through Monday...An upper level trof is approaching from the west this morning. A few isolated thunderstorms have developed west of Monida Pass this morning. Thus low pops have been placed over the western half of the CWA this morning. The main trof/front move eastward through the CWA this afternoon. There is the potential for isolated severe storms over the western portions of the CWA, but as the disturbance approaches the eastern portions of the CWA, particularly the Lewistown area, there is a higher potential for severe storms. The HREF progs a convective band of 60 mph wind gusts through Fergus County as the boundary moves through between 4 and 7 PM. Overall, most areas east of a line from Lincoln to Havre are in a Marginal Risk for severe storms, while the Judith Gap, Lewistown and Grass Range areas are in a Slight Risk. There is also the potential for large hail with the stronger storms as well today. I did lower afternoon temperatures just a few degrees, as cloud cover today will limit max temp rises a bit. Expect most showers/thunderstorms to exit the eastern portions of the CWA this evening, but another round of showers/thunderstorms is expected on Monday, especially over Southwest MT. At this time, no severe storms are expected on Monday. 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 && .PRELIMINARY POINT TEMPS/POPS... GTF 77 53 77 53 / 40 30 20 30 CTB 72 51 72 50 / 70 10 50 30 HLN 79 55 80 54 / 60 50 30 30 BZN 80 50 75 46 / 80 60 60 50 WYS 79 44 67 37 / 40 70 80 80 DLN 77 48 73 42 / 70 50 50 40 HVR 78 55 78 54 / 20 40 40 30 LWT 79 50 73 49 / 30 60 20 20 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && $$ http://www.weather.gov/greatfalls