Marine Weather and Tide Forecast for Big Timber, MT

DISCUSSION
Through Saturday night...

Large cumulus field had formed over the area under steep lapse rates and the departing trough this afternoon. Radar showed the cloud field to the N and NE of KBIL with possible embedded showers. Kept isolated showers thru the evening E and S of KBIL due to the instability. Pressure gradient will increase overnight resulting in gusty winds in KLVM/Nye, and from Judith Gap to K6S0. Pattern also supported some gusty winds for KBIL, so have raise winds late tonight through early Saturday for these areas, resulting in gusts in the 20s to lower 30s mph.

High pressure ridge flops over into the region on Saturday. Good mixing will promote high temps into the upper 50s to lower 60s as well as low RH's. Opted to go above the NBM by a few degrees for temps and blended with the GFS to get lower RH's. Also, the good mixing will cause gusty afternoon winds, so have blended winds and wind gusts with the NBM 90th percentile. Next cold front will push E into the area late Sat. afternoon into the evening. The front will cross most of the forecast area, except for the 4 eastern MT counties, by 12Z Sunday. There was not much frontogenesis or QPF with the front. Probabilities of QPF of a tenth of an inch were only around 10% from KBIL W. The western mountains had small areas of 20% probability. Forecast reflected this low QPF and had PoPs of 20-30% W of Rosebud County late Sat.
night. Precipitation type will be rain over the lower elevations with snow in the mountains. Arthur

Sunday through Friday...

Saturday night into Sunday, energy ahead of shortwave troughing will provide weak forcing and subsequent scattered showers across the region. The main frontal passage associated with the trough looks to move through early Monday bringing a bulk of the precipitation. There is still a lot of uncertainty amongst ensembles concerning the amount of moisture with this system for areas west of Billings. With that being said, areas of Yellowstone Co west have moderate to high chances of getting at least a quarter inch of liquid with this system. As far as snowfall goes, being this isn't a particularly cool system, snow levels will be around 6kft. The Beartooth/Absarokas have around a 50-70% chance of getting at least 6 inches of snow at the highest peaks Sunday and Monday. Snowfall will likely favor the W/SW facing slopes with this system. Ensembles look to keep unsettled weather and precip chances in the forecast for the remainder of the week.

High temperatures will be in the 50s and low 60s through the period. TS

AVIATION

Southwest winds will pick up at KLVM and KBIL with gusts up to 20-30 kts mainly through the afternoon Saturday. VFR will prevail through the period. TS

PRELIMINARY POINT TEMP/POPS

Sat Sun Mon Tue Wed Thu Fri ----------------------------------------------------------- BIL 028/060 040/061 040/056 036/057 036/058 039/056 041/059 00/N 24/W 78/W 42/W 13/W 33/W 34/W LVM 025/054 036/058 036/051 028/053 032/054 036/052 037/055 00/N 35/W 99/W 32/W 23/W 34/W 35/W HDN 024/060 035/061 037/058 034/057 034/060 038/058 040/062 20/U 25/W 69/W 52/W 23/W 34/W 44/W MLS 026/061 034/059 037/059 036/054 033/059 038/058 039/057 00/U 03/W 37/W 42/W 11/B 33/W 33/W 4BQ 026/057 032/058 037/060 037/056 034/060 040/056 041/057 20/U 02/W 16/W 42/W 12/W 33/W 43/W BHK 023/057 030/059 034/059 033/054 029/058 034/055 034/055 20/U 01/B 17/W 43/W 12/W 34/W 33/W SHR 017/053 029/056 032/057 030/055 029/059 034/054 036/060 20/U 14/W 28/W 42/W 13/W 34/W 44/W

BYZ WATCHES/WARNINGS/ADVISORIES
MT...None.
WY...None.