Area Forecast Discussion
Issued by NWS Billings, MT

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000 FXUS65 KBYZ 281550 AFDBYZ Area Forecast Discussion...Updated National Weather Service Billings MT 950 AM MDT Thu Mar 28 2024 .UPDATE...
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A dynamic cold front, supported by strong forcing/instability aloft, will move across the forecast area from west to east this afternoon/evening. Timing into Livingston is around 1pm, Billings 3pm, Sheridan 6pm, Miles City 7pm. This cold front will be supported by outflow winds from convection along it, and as such will see the potential for 40 to 50 mph wind gusts with locally stronger gusts possible. Adjusted forecast to add mention of thunderstorms based on the latest CAM models, lining up with SPC`s general thunderstorm outline which is areas generally west of a Sheridan to Hardin to Forsyth line. Given the low freezing levels this time of year small hail/graupel will be possible with any storms along with brief heavy precipitation which may be a mix of rain/snow. Ahead of the front, forecast in good shape with high temperatures looking to push into the 50s to low 60s for most locations. Chambers
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&& .DISCUSSION... Today through Friday... Satellite imagery shows a ridge axis over eastern MT and dirty SW flow in advance of a Pacific coast trof. The main shortwave of interest (to affect us later today) is moving thru northern CA. Surface analysis shows a modest lee side trof over central MT. Latest IDA-LWT gradient is only 6mb, and YNP is not terribly cold, but nonetheless Livingston flirted with 50 mph through the evening into the overnight hours, with a peak of 55 mph. Now at 08z we are seeing gusts starting to decrease, and this trend will continue thru the morning. Pre-frontal downslope warming will push temps into the 50s to lower 60s most places today, with some inhibition possible due to cloud cover. Pacific cold front is set to arrive in the early afternoon in our west and mid to late afternoon in the Billings area (and eastward thereafter). We will see showers along and behind the front, and there may be enough instability (100-200j/kg of cape) to produce a few rumbles of thunder, mainly for the west half of our cwa. The combination of a fropa and convection/steep lapse rates will produce a brief period of gusty W-NW winds, with localized 40+ mph gusts. Furthermore, it looks as if wet bulb zero heights will fall enough to change ptype to wet snow, or a rain/snow mix, along the western foothills in the late afternoon & evening. Lower elevation snow accumulation will be an inch or less, but late day travelers should stay alert for rapid changes and potentially poor visibility (along with the wind of course). The Beartooth-Absarokas have picked up a little orographic snow already - an inch or two at Fisher Creek Snotel over the last several hours. As lapse rates steepen the snow in the mountains will turn heavy for a few hours later today and this evening. Totals for our western mountains should reach 4-8". A nice quick addition of SWE where it`s really needed. Shower activity will taper off late tonight. On Friday, with building lee side pressures and another weaker shortwave emerging from the SW flow aloft, winds will turn around to an upslope direction. There is a good (40-50%) chance of rain/snow especially close to the foothills by Friday afternoon. Expect temps to take a step down tomorrow with highs in the 40s to around 50F. Here are a few notable probabilities: 40+ mph wind gusts in our west today: 40% 4" of snow over the western mtns today/tonight: 85% 8" of snow over the western mtns today/tonight: 10% 0.10" of pcpn at lower elevations today/tonight: 40% west of Rosebud County, 10% east. JKL Friday Night through Thursday... The flow starts of the weekend becoming unsettled as heights lower due to a system pushing south and east across southern Canada. Its associated backdoor cold front swings through the area Friday night, shifting winds to the east and cooling off the area, with highs for the weekend being 5-10 F degrees below normal. Some light rain/snow will occur on Saturday, but minimal impacts are expected from it. On Sunday, a dynamic trough cuts inward across the southwest CONUS and brings heavy precipitation to much of the western CONUS. Southern MT and northern WY stay on the far northern extend of it, as this upper low looks to stay well south of us, and leaving it`s ascent down south with it. That said, we do get a surge of moisture to cut across the area, and combined with some usplope flow and low-level divergence will bring some rain and snow to the area. Confidence is increasing for it to stay mostly confined to the foothills and far southeast MT. While most of the snow will likely melt within a day of it falling, greatest impacts will be for travel Sunday evening through Monday morning, especially along US-212 and I-90 south of Crow Agency. Rain that falls before switching over to snow could result in icy roads Sunday night as well. Plan accordingly if you plan to travel along these roads during this time frame. High confidence in an upper ridge building back in for the start of the work week and quickly bring temperatures roaring into the low 60s by Tuesday afternoon. The mid to latter half of the week is where uncertainty comes into play again. It`s about a 50/50 split if we stay under ridging on Wednesday and Thursday and keep the warm and dry conditions, or if we start to re-introduce rain and snow showers to the area due to some cyclonic flow and lowering heights about 50% of ensemble members bring want to bring in. Vertz && .AVIATION... SW wind gusts of 30-40 knots will impact KLVM early today, then winds will gradually decrease after sunrise. A moist Pacific flow is producing snow over SW aspects of the Beartooth-Absarokas, and these mountains will be frequently obscured. VFR will prevail elsewhere through early afternoon. A Pacific cold front will bring showers and gusty winds (and perhaps a few rumbles of thunder) from mid afternoon through the evening. Local MVFR is possible w/ the shower activity, and mountains will be obscured in heavier snow. The front is expected to produce a wind shift to W-NW winds gusting 25-35 mph along the western foothills and eastward to KBIL. JKL && .PRELIMINARY POINT TEMP/POPS...
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Tdy Fri Sat Sun Mon Tue Wed ------------------------------------------------------- BIL 060 032/049 029/042 028/044 028/056 033/066 042/064 7/T 63/W 34/O 26/O 31/B 00/U 14/R LVM 052 028/047 028/043 025/043 026/052 032/062 038/059 9/T 74/W 33/O 24/S 20/B 00/U 13/R HDN 062 030/051 027/044 027/046 025/055 029/067 037/065 5/T 62/W 24/O 26/O 41/B 00/U 24/R MLS 057 030/045 025/041 026/042 025/050 028/061 039/061 1/E 50/B 03/O 12/R 21/B 00/U 12/R 4BQ 063 032/048 027/044 028/043 027/048 029/061 039/064 1/B 30/B 14/O 24/O 41/B 00/U 12/R BHK 050 027/043 021/040 023/039 021/046 024/056 034/060 0/N 51/B 03/O 22/S 21/B 00/U 11/U SHR 063 030/048 026/044 025/043 026/049 027/061 035/064 2/T 43/W 35/O 47/O 62/S 00/U 13/R
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&& .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$ weather.gov/billings

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