Marine Weather and Tide Forecast for Bozeman, MT

DISCUSSION

Through Monday...

As Yesterday's storm system continues to slowly push out of the region, widespread westerly winds are forecast to become dominant. This is the main reason that there is minimal concern for any fog development this morning, however, locations farther away from the downslope impacts of the mountains may see some patchy fog. This includes the river valleys as well as locations near the Dakotas. If any fog were to form it would likely be patchy in nature.

After this morning, our attention turns to the potential for an impactful storm mid to late week. Deterministic models are now starting to show more of a split flow event keeping some of the energy up into SK and digging some of the energy down into CO.
Some of the latest ensembles are also depicting a split of the energy as well, albeit more modest. This flow would likely result in lee-side cyclogenesis farther south along the front range which will in turn bring the greatest forcing off to our south.

The specifics of how far south the trough digs will make a huge difference for some locations snowfall totals. The greatest discrepancies are in the mountains and the foothills on the NE and East sides of the ranges. Previous model runs that show more of a single upper level low dive into WY were showing 2' totals in some locations of the Beartooth/Absarokas whereas these models have recently trended closer to a 12-18". We still are 36 hours out from knowing exactly where this system will end up, however, the trends are for less precipitation. It is worth noting though that some ensemble members are still showing large snow totals in all of the mountains.

Even if the main energy ends up having less impacts on our area, this does not mean that we will completely miss out on all precip.
The surface low pressure that forms along the MT/AB border will push through NE MT and have a trailing cold front along with it.
This brings chances for precipitation to places near and West of Billings as soon as midday Wednesday and the entire CWA by Wednesday evening. While most of the area will start out as rain with snow levels around 6 kft, behind the FROPA the temperature cools rapidly. The exact timing of the cold front remains just as uncertain as the parent feature does but most models have it move through Billings by early afternoon Thursday. A transition to snow may occur as early as Thursday afternoon in Billings and Thursday evening in Sheridan and Miles City. As is common with these systems, the coldest air moves in just as the precip moves out meaning that minimal snowfall is expected for most locations.

The exception to the minimal snowfall could be along the foothills near Red Lodge, MT and Story, WY. These locations precip totals will also be highly dependent on the actual track of the low. It does appear that regardless of the exact track that there will be at least a brief period of upslope enhancement into these areas.
The timing, intensity, amount of moisture, and snowfall amounts are still very uncertain. The brief period associated with the cold front is looking more likely than the TROWAL with the main surface low advecting in moisture at this time. As of right now it looks like these upslope regions may only see 1" of snow behind the cold front that will have trouble accumulating on warm ground.
On the flip side, the NBM 90th percentile is showing roughly 8" for these areas. In short there could be impactful snow or next to nothing. Along with the potential for accumulating snow in Sheridan Co, there may also be a brief period of near blizzard conditions associated with the strong push of winds along and just behind the front.

Due to the strong CAA, cool temperatures are forecast to end the work week. While some areas in the plains may be able to push up to their average high temperature Thursday, locations west of the Bighorn River will be 5 to 10 F below average with highs in the 40s. Friday will see highs roughly 10 F below average across the region. Highs in the 40s will be widespread with localized upper 30s.

The good news with this event is that regardless of p-type or exact rainfall totals, any additional precip is welcome to help with the drought across the CWA After this event it looks like an active pattern will continue through the end of the month with repeated chances for precipitation. WMR

AVIATION

There is a slight chance (20 percent) for patchy fog over eastern Montana into this morning. Any fog that does develop will lift by mid-morning. Look for VFR conditions to prevail today for most locations. A few showers are possible over and near the southern mountains/foothills and VC KSHR this afternoon. Local MVFR and some mountain obscurations are possible with the showers. Winds will remain breezy at times along the western foothills through the period, from KLVM to K6S0 and KHWQ. STP

PRELIMINARY POINT TEMP/POPS

Tdy Wed Thu Fri Sat Sun Mon ------------------------------------------------------- BIL 066 042/068 038/048 028/048 028/057 033/068 040/075 0/B 11/B 58/W 54/J 21/U 00/U 01/B LVM 062 038/060 030/039 021/042 023/053 029/063 037/069 1/N 05/W 99/J 66/J 30/U 00/U 11/N HDN 067 037/071 038/052 026/047 024/056 028/069 036/077 1/U 01/B 48/W 64/J 31/U 00/U 01/B MLS 066 040/070 040/053 025/042 022/051 027/065 038/074 0/U 00/B 34/W 32/J 11/U 00/U 00/U 4BQ 064 037/071 042/057 025/040 020/049 026/065 037/075 1/B 00/U 14/W 63/J 11/U 00/U 00/U BHK 065 037/068 038/057 023/039 019/046 024/060 033/069 1/U 00/U 12/W 52/J 11/U 00/U 00/U SHR 061 032/066 037/052 023/040 018/049 024/063 033/071 2/W 00/B 29/W 96/J 32/W 00/U 01/B

BYZ WATCHES/WARNINGS/ADVISORIES
MT...Winter Storm Watch in effect from Wednesday evening through late Thursday night FOR ZONE 67.
WY...None.