058 FXUS65 KBYZ 260156 AFDBYZ Area Forecast Discussion National Weather Service Billings MT 756 PM MDT Thu Oct 25 2018 .UPDATE... Evening satellite imagery shows a good deal of mid and high cloud spilling over a northern Rockies ridge and into our region. Downslope gradients will remain in place and tighten a bit through the night, in response to a weak shortwave sliding over the ridge. Foothills winds may decrease some through the remainder of the evening, then should increase overnight in response to the lee side pressure falls. Gusts will likely approach 50 mph late tonight and tomorrow at Livingston, Big Timber and Harlowton... but don't see enough mid level support (or cold air/stability) to reach highlight criteria. The combination of wind and cloud cover will yield a warm night especially along the foothills. The weak shortwave will likely bring a few showers to our mountains and western half of our cwa late tonight into Friday morning. Have raised sky cover based on satellite imagery, upped forecast lows in our west a few degrees, and tweaked overnight pops based on latest model trends. Forecast is in good shape. JKL && .SHORT TERM...valid for Fri and Sat... Weak disturbance which brought some isolated showers to mainly the Big Horns region has moved southeast leading to decreasing clouds from north to south. As another short wave approaches from the northwest we will see the pressure gradient tighten across the foothills. So increasing wind as we have advertised still looks like a good bet from Livingston to Big Timber. The gradient will let up Friday before tightening again Friday night into early Saturday. At this time, it does not look like winds will be quite strong enough for any highlights. We are concerned about hitting high wind warning criteria in Wheatland County and across Highway 191 possibly Friday and Saturday as 700mb winds increase and are favorably oriented to hit this area. A stronger clipper type weather system will move across the northeast corner of Montana into the Dakotas Saturday. This is associated with the jet stream which will be arched over Montana and into the Dakotas. Previously, we had concern about high winds in the eastern border counties from Baker to Miles city and south. However, recent model runs have trended the strongest 850mb winds to the east. So while we will still have a very windy day, high wind warning criteria looks less likely. The system on Saturday does have some moisture involved with a period of good lift and decent lapse rates during the mid morning hours. The best chance of measurable rain is over the mountains and areas east of Billings where the downslope effect decreases and jet dynamics will play a significant role. But drier air and subsidence quickly come into the area Saturday afternoon. Winds and clouds will decrease Saturday night as the system moves east. BT .LONG TERM...valid for Sun...Mon...Tue...Wed...Thu... No large changes were needed from previous extended forecast. Ensembles and deterministic models were in decent agreement with large scale pattern through the period, however, there was some uncertainty at times with the pattern in the ensembles. Super Typhoon Yutu in the western Pacific could cause model changes downstream, so the extended forecast may change with time. On Sunday, the region will be under an upper ridge with mild and dry conditions and much lighter winds than on Saturday. Did add a slight chance of showers to the western mountains early as a weak wave and moisture moves into the area. A Pacific shortwave will push a cold front through the area Sun. night through Monday with low chances of precipitation over parts of the area. Precipitation chances will fade S during Mon. night. Monday will be cooler than Sunday with seasonable temperatures in the 50s. Upper trough will be over the area on Tuesday with slight chances for rain and snow showers and cooler conditions in the 40s. On Wednesday, region will be under NW flow with energy and a cold front pushing through the area. The NW flow continues on Thursday. Will have chances for rain and snow with highs mainly in the 40s. Arthur && .AVIATION... VFR conditions will prevail through Friday across the area. Expect localized mountain obscurations over the western mountains on Friday. Surface winds will decrease this evening, but will begin to increase again Friday morning, especially around KLVM where there will be gusts to 40 kt. Gusty winds will persist over the area into the afternoon with wind gusts into the 20s and 30s, and gusts into the 40s around KLVM and Big Timber. Arthur && .PRELIMINARY POINT TEMP/POPS... Fri Sat Sun Mon Tue Wed Thu ----------------------------------------------------------- BIL 044/067 045/061 034/062 038/054 035/049 032/050 034/049 02/W 23/W 00/U 13/W 22/W 12/W 43/O LVM 044/063 044/059 032/062 036/051 032/044 030/048 032/047 02/W 33/W 01/B 33/W 33/W 22/W 43/O HDN 038/068 043/062 032/063 036/057 033/051 031/050 031/050 02/W 34/W 00/U 02/W 22/W 12/W 33/O MLS 039/065 043/060 032/059 036/056 033/050 029/048 031/048 01/B 25/W 00/U 21/B 11/N 11/B 23/O 4BQ 039/066 043/061 033/059 037/058 033/051 029/048 031/047 00/B 24/W 00/U 01/B 21/N 11/B 33/O BHK 036/062 039/058 030/058 032/057 031/047 027/046 027/045 00/B 13/W 00/U 11/B 12/W 11/N 22/O SHR 038/065 042/060 032/062 035/057 031/048 027/048 029/046 01/B 23/W 00/U 02/W 32/W 11/B 23/O && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$ weather.gov/billings