FXUS65 KTFX 080238 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 838 PM MDT Wed Aug 7 2024 .SYNOPSIS... Cooler temperatures will remain across the region through the end of the week. Chances for showers will remain each day through early next week. Temperatures trend warmer this weekend into early next week, but still linger a touch below normal. && .UPDATE... Tonight isolated rain showers have the potential to linger across North-central, Central, and Southwestern Montana. In any areas where skies clear and winds are light across North-central, Central, and Southwestern Montana fog will form. However, at this time there is low confidence that skies will clear. Sky grids were tweaked through tomorrow morning to better reflect current satellite trends. Minor tweaks were made to the hourly temperatures, hourly dewpoints, hourly relative humidity, and winds. The rest of the forecast is on track. -IG && .AVIATION... 08/00Z TAF Period VFR conditions will prevail at all terminals for this TAF period excluding at the KGTF and KHLN terminals. However there will be scattered MVFR to IFR level clouds at the KHVR, KCTB, and KLWT terminals during this TAF period. At the KGTF terminal there will be MVFR ceilings intermittently around for the next couple of hours. At the KHLN terminal there will be MVFR ceilings between 13 and 15Z. Tonight at all terminals excluding the KWYS terminal there is a 20 - 30% chance for showers and thunderstorms. If skies clear then at all terminals excluding the KHLN and KBZN terminals fog will form. However at this time there is low confidence that skies will clear and so there is no mention of mist/fog in any of those TAFs. At all terminals excluding the KEKS, KWYS, and KHVR terminals there is 20% chance for rain showers between 12Z and 18Z. Mountain obscuration will continue intermittently, primarily across North-central and Central Montana through 18Z. -IG Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PREV DISCUSSION... /ISSUED 600 PM MDT Wed Aug 7 2024/ Through Thursday... Northerly to northeasterly surface flow across the plains will combine with a weak embedded wave pivoting through cyclonic northwesterly flow aloft across the Northern Rockies today to result in showers and a few thunderstorms through the afternoon, primarily across Central and North-central Montana. Given overall instability is significantly lower for today, and that upper level support wanes as we get deeper into the afternoon and early evening, any thunderstorms that do form look to be more run-of- the-mill variety. Temperatures across the plains this afternoon will struggle to warm much at all, largely only reaching into the 60's, though a few locations across the eastern plains will sneak into the lower 70's. The coolest air will take a bit longer to spread into Central and Southwest Montana valleys, arriving on a briefly breezy northerly wind late afternoon and early evening. Those with outdoor plans should be prepared for this brief period of gusty winds out of the north, especially in north-south oriented valleys. Looking towards tonight, northeasterly surface flow will maintain low end shower chances. Areas where winds lighten sufficiently and overlap with a lack of cloud cover have the potential to see some patchy fog. Cool temperatures persist into Thursday as westerly to northwesterly flow aloft continues. Most areas look to stay dry, though showers will be around along the Rocky Mountain Front and across Central Montana terrain. -AM Friday through next Wednesday... Ensemble model forecast clusters indicate that Montana will generally remain under a slightly anti- cyclonic westerly flow aloft, between a broad low pressure trough in Canada and a broad high pressure ridge over the Southwestern and South Central United States. As a result, the National Blend of Models is tending not to forecast any significant swings in the weather into next week. The overall trend is for a very gradual warm- up in temperatures, though they should remain below seasonal averages. The relatively unsettled pattern will also keep a chance for showers and thunderstorms over the forecast area each day, with the best chances occurring Saturday through Sunday; this is when forecast have at least moderate agreement in moving a shortwave trough through the area. -Coulston && .PRELIMINARY POINT TEMPS/POPS... GTF 49 69 48 74 / 20 20 0 0 CTB 45 67 44 71 / 30 20 10 0 HLN 53 76 50 81 / 20 20 0 20 BZN 49 74 46 78 / 20 20 10 20 WYS 40 74 40 75 / 10 10 20 60 DLN 46 74 46 77 / 10 10 10 40 HVR 48 74 46 78 / 30 10 0 0 LWT 43 66 42 70 / 20 20 0 0 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && $$ http://www.weather.gov/greatfalls