Marine Weather and Tide Forecast for Big Timber, MT

DISCUSSION

Rest of Today through Sunday night...

Upper low over the Rockies (centered over Idaho) will slide east tonight. Upper jet (100 kts) on leading east side of low will shift right over our western CWA early this evening. Jet dynamics coupled with height falls and steep lapse rates will initially result in a relatively narrow band of precipitation developing from around the Pryors northward this evening. Possibly intense showers with some thunder is possible under this band during the evening. Other scattered showers and possibly isolated thundershowers, may develop across the area through the evening as well as coverage expands overnight. By Sunday, widespread rain with isolated embedded thunder is expected over much of the CWA as the energy on the upper low lifts northeast across Montana.
Sunday will be a wet, cool and brisk day for most locations.
Look for precipitation to slowly decrease from southwest to northeast Sunday evening as main upward forcing shifts out of our area.

The area with the best chance of significant precipitation is our central zones from the Pryors north, where the chance of an inch of precipitation is 25-40%...mainly for Billings and surrounding areas. The chance of at least a half inch of precipitation for this whole event ranges from 40-90% from Rosebud County westward, with less than a 10% chance over our far eastern counties.

Winter Weather...We still expect to see any precip turn to snow in the high country later this evening and continue through Sunday. Snow levels are progged to drop to near 7500 ft by Sunday morning in our western mountains. Accumulating snow is generally expected over 8000 ft with the mid level flow favoring the west facing slopes in the Beartooth/Absarokas. The heaviest snow rates will likely occur Sunday morning. A winter weather advisory continues for the high country from 6 PM this evening to 6 PM Sunday, particularly for the Beartooth Pass, where 3-6 inches of snow may accumulate. Roads may become slick and quite slushy.
Please plan to check for possible road closures if you plan to travel the Beartooth Pass this weekend. Any outdoor recreation in the high country may encounter raw winter weather conditions...so plan accordingly.

Highs Sunday will range from lower 50s west to lower 60s east.
The coldest overnight temps are expected Sunday night as clouds clear out, ranging from lower 30s west to around 40 east. Local frost is possible over portions of our west including Park and Wheatland Counties. Currently, the chance of 32 degrees or lower for Livingston and Harlowton by Monday morning is 25%. BT

Monday through Saturday...

Monday morning, the system from this weekend will be exiting off to the east. Some isolated rain showers with mountain snow may be lingering around, however, most to all of the precip should be over by mid morning. As this system pushes out and a cutoff low sets up over the four corners region, weak ridging develops over MT on Tuesday and should last through Wednesday. This will allow temps to rebound back to average by mid-week.

Starting late Wednesday and through the end of the week, the models are in disagreement in regards to specifics of what happens. There is a general agreement in the overall pattern though that Thursday will be the warmest day of the week before the next trough is able to shift all of North America back into a progressive pattern. The disagreement lies with what exactly this advancing energy will do. Some solutions want to give the CWA another chance for widespread precip and a cooler weekend yet again, while other solutions are showing just a glancing blow.
This will need to be monitored more closely once mid-range models are able to pick up on this time period. WMR



AVIATION

Expect west to northwest winds gusting 15 to 30 kts to be common through about 01Z this evening...decreasing thereafter. Areas of precipitation will develop across south central Montana by early evening with coverage spreading through the night. Mountains will likely become obscured and snow levels falling to near 8000 ft.
Embedded thunder is possible in the widespread showers. Local MVFR is possible due to moderate rain limiting visibility during the evening hours. MVFR ceilings are expected in the KLVM vicinity after 06Z, spreading east to KBIL by 12Z. Widespread IFR/MVFR conditions expected for most areas Sunday with areas of rain and some embedded thunder. BT



PRELIMINARY POINT TEMP/POPS

Sun Mon Tue Wed Thu Fri Sat ----------------------------------------------------------- BIL 047/058 042/071 049/077 053/083 057/086 056/082 056/079 89/T 31/U 02/T 12/T 01/B 22/T 32/T LVM 037/056 032/069 039/075 044/080 049/083 048/080 048/078 79/T 41/U 12/T 12/T 11/B 23/T 32/T HDN 047/058 040/072 048/077 052/082 055/087 055/083 054/079 79/T 30/U 12/T 22/T 11/U 22/T 42/T MLS 052/058 043/073 050/080 056/082 057/088 059/085 057/080 57/W 20/U 23/T 43/T 21/U 22/W 42/T 4BQ 052/060 042/071 052/077 054/079 055/086 059/085 057/078 44/W 10/U 34/T 43/T 21/U 11/U 32/T BHK 052/062 042/069 048/076 052/076 053/083 056/084 054/078 43/W 10/U 24/T 44/T 21/U 22/W 32/T SHR 045/058 037/071 046/075 048/078 049/085 051/083 050/077 68/T 20/U 24/T 33/T 11/U 12/W 23/T

BYZ WATCHES/WARNINGS/ADVISORIES
MT...Winter Weather Advisory in effect from 6 PM this evening to 6 PM MDT Sunday FOR ZONE 67.
WY...None.