Area Forecast Discussion
Issued by NWS Great Falls, MT
Issued by NWS Great Falls, MT
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786 FXUS65 KTFX 160420 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 1020 PM MDT Sat Jun 15 2024 ...Aviation Section Updated... .SYNOPSIS... This afternoon, thunderstorms and showers move through the area. Some of these thunderstorms have become severe producing erratic high winds. Aside from winds associated with thunderstorms, gusty winds develop across the region, with high winds forecast along the Northern Rocky Mountain Front and the adjacent plains. These strong winds continue through tomorrow morning. Next week, cooler temperatures and widespread precipitation are forecast. && .UPDATE... Updated forecast is out. No major changes to the current forecast overnight. Most of the precipitation has exited the CWA. There is a 20 percent chances showers could redevelop after Midnight for areas mostly north of Highway 2. Otherwise, periods of strong winds are expected in the Browning/Cut Bank areas overnight and into Sunday morning. Cut Bank did record a 58 mph gust earlier this evening already. Thus, no changes to the high wind statement. Cooler air is now moving into the region, with the cooling trend to continue for the next few days. Looking ahead to the late spring storm, Central MT looks like it has the highest probability of receiving the most precipitation with this system. With that said, snow amounts have decreased over the Glacier Park region, and that winter storm watch might end up being cancelled for that area, depending what the 0z runs shows tonight. Otherwise, the rest of the winter storm watches remain on track, generally using the lower threshold of 6 inches for potential warning decisions. Brusda && .AVIATION... 16/06Z TAF Period VFR conditions will prevail for across all terminals through 12z Sunday after which increasing shower activity and lowering CIGS along the International Border may begin to usher MVFR conditions south towards the KCTB and KHVR terminals. Confidence in these MVFR conditions occurring is approximately 20-40% at this time, so withheld mention of MVFR conditions for the TAF package given the low probabilities. Otherwise the biggest concern to terminals will be strong and gust west winds, particularly at the KCTB terminal where frequent wind gusts approaching 50kts are expected through 12- 15z Sunday. Strong mid-level winds will also contribute to mountain wave turbulence and instances of low level wind shear through 12-18z Sunday over the plains of Central and North Central Montana. Winds will gradually begin to subside from late Sunday morning and through the afternoon hours. Mountain obscuration is likely along the Continental Divide and North Central Montana for most of the next 24 hours. - Moldan Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PREV DISCUSSION... /ISSUED 230 PM MDT Sat Jun 15 2024/ Today...Thunderstorms and showers have developed, and are moving across the region. Some of these storms have become severe, producing high winds that are erratic in nature. Additionally, periods of heavy rainfall accompany these storms. Aside from winds associated with these thunderstorms, strong gusty winds have developed across the region. High winds are forecast across the Northern Rocky Mountain Front and the adjacent plains. These winds are forecast to continue into tomorrow morning. Tomorrow...A cooler day is forecast. Generally, dry conditions prevail, with some moisture forecast along and north of the Hi- Line. As the day progresses, wind speeds decrease. - Fogleman Monday through Wednesday...Ensemble clusters continue to support longwave troughing moving over the Northern Rockies throughout the period, with the leading modes of uncertainty being the amplitude of the trough as it moves over the Great Basin on Monday and then the position and/or timing of the trough on Tuesday and Wednesday as it lifts northeast to over the High Plains. With respect to Monday`s uncertainty, main impacts to North Central through Southwest Montana will be just how "cold" and wet conditions will be, with high temperature spreads across lower elevations between the 25th and 75th percentiles being approximately 10-15 degrees from the upper 40s/low 50s (25th percentile) to the upper 50s/low 60s. Additionally, precipitation spreads for Monday and Monday night range from a couple hundreths over northern and southern portions of North Central and Southwest Montana (respectively) to 0.10"-0.25" elsewhere for the 25th percentiles, with 0.25" to just over 1" for the 75th percentiles. These large spread between temperatures and precipitation also leads to uncertainty with respect to the type of mountain precipitation, with NBM probabilities for 6" or more of snow from Monday through Tuesday generally ranging between 30-50%. Have continued the Winter Storm Watch from Monday through Tuesday given this uncertainty, but regardless if the Watch is upgraded to an Advisory or Warning or cancelled...recreationists should be prepared for cold and raw conditions. Additionally, should higher end snowfall amounts materialize over this timeframe, damage to tree limbs and power outages would be possible given the heavy, wet nature of the snow. High temperatures will warm slightly for Tuesday and Wednesday, but remain below normal. Light precipitation is expected linger through the morning and early afternoon hours on Tuesday, with overall drying conditions expected thereafter. Thursday through next Saturday...Ensemble clusters largely support and unsettled southwest flow regime over the Northern Rockies for the second half of the work week and into next weekend, which would translate to moderating temperatures and daily chances for showers and thunderstorms. - Moldan && .PRELIMINARY POINT TEMPS/POPS... GTF 41 65 42 51 / 0 0 40 80 CTB 40 59 36 56 / 10 30 20 60 HLN 42 67 44 53 / 0 0 60 90 BZN 35 66 40 56 / 10 0 40 90 WYS 35 60 37 51 / 10 0 10 60 DLN 33 65 38 51 / 0 0 40 80 HVR 44 64 42 57 / 10 20 20 80 LWT 37 63 38 51 / 10 0 40 90 && .TFX WATCHES/WARNINGS/ADVISORIES... High Wind Warning until 9 AM MDT Sunday for East Glacier Park Region-Eastern Glacier, Western Toole, and Central Pondera- Northern High Plains-Southern High Plains. Winter Storm Watch from Monday morning through Tuesday evening for East Glacier Park Region-Southern Rocky Mountain Front. Winter Storm Watch from Monday evening through Tuesday evening for Big Belt, Bridger and Castle Mountains-Elkhorn and Boulder Mountains-Gallatin and Madison County Mountains and Centennial Mountains-Little Belt and Highwood Mountains-Northwest Beaverhead County. && $$ http://www.weather.gov/greatfalls