Marine Weather and Tide Forecast for Big Timber, MT

UPDATE
Satellite imagery shows a weak shortwave lifting from northern NV into southern ID, and there are some showers & weak t-storms in southeast ID. Some benign activity may spread into the Beartooth- Absarokas later this evening into the overnight hours. Most of the cwa will be dry tonight, but the advection of low cloud into far southeast MT may yield spotty drizzle later tonight, but the risk of fog is low per the breezy southerly winds. Something to watch.
Better chance of upslope stratus and perhaps localized fog is west of Billings and in particular the east side of the Crazy Mountains. Look for low temps tonight in the mid 30s to lower 40s most places. Current forecast has all of this covered well. JKL

DISCUSSION

Through Saturday Night...

Mostly dry conditions under partly to mostly cloudy skies will continue into tonight as a weak upper low progresses through the region. With that said, an isolated shower or two are possible this afternoon and evening over the higher terrain to the south of Billings, but the chance of precipitation remains low (5 to 20 percent). As we progress into tonight, the breezy winds over south-central Montana look to taper off. With this, localized patchy fog is possible once again into the morning hours.
Therefore, if you commute on Highway 191 from Big Timber through Harlowton, stay alert for patchy fog Saturday morning. East of Billings over south-eastern Montana, breezy winds will continue into tonight with gusts generally around 20 to 35 mph.

Saturday will be a mostly dry day as our next weather system moves inland over California. While the core of this system will still be far away, divergent south-west flow along with modest instability will allow scattered showers and isolated thunderstorms to develop during the afternoon and evening over south-central Montana. Any thunderstorm that does develop will generally be weak, but small hail and gusty winds are possible.
Temperatures Saturday will also be warmer than today with highs in the 60s and 70s (F). Arends

Sunday through Friday...

The synoptic forecast remains on track with a strong upper level low progressing eastward during the day Sunday bringing precip across the area to start the work week.

Rain/snow showers will fill into the mountains through the day Sunday, and as we progress into Sunday afternoon and evening the chance for thunderstorms develops across the eastern half of the CWA NBM has forecast SFC CAPE values over 800J/Kg in some locations in southeast Montana with widespread 500+ J/Kg.
Additionally, very steep lapse rates will be the theme for the region as a GFS forecast sounding pulled near KMLS shows SFC-3KM lapse rates approaching 9C/KM. The other thing that caught my eye with this sounding is that the lowest levels show northeasterly winds with a sickle shaped hodograph. This will allow for good moisture advection and WAA into the region which could also help increase some SB CAPE. The primarily inverted-V soundings will make strong winds the primary hazard, however some modest hail is also possible with some of the stronger storms.

Snow levels for the event have also changed slightly. The start of the event will see levels near 8,500ft with gradual falls to near 6,000ft. This has cautiously decreased the concern for flooding of the Elk Fire burn scar as most of the heaviest precip should fall as snow. That being said, the lowest elevations of the scar could see rain for a little longer into Monday morning leading to localized flooding. Once the snow begins in the Absaroka/Beartooth mountains snow could be heavy at times totaling 18"+ at the highest peaks by Tuesday AM as the system makes a rapid exit to our east.

The next chance for precip will be Wednesday afternoon as a speedy shortwave moves in from the NW. This could give us another chance for some showers and thunderstorms Wednesday afternoon and evening region-wide with mountain snow. After that shortwave exits to the east, there is great consensus in a building ridge towards the end of the week. The specifics of whether this ridge will be more neutrally oriented or flopped over a quasi-cutoff low is yet to be determined. Regardless, clear skies and temps in the 70s seem likely late next week. WMR

AVIATION

The scattered to broken MVFR clouds over south-central and eastern Montana this afternoon will continue to break up into this evening. With easterly surface winds continuing into tonight, areas along the western foothills (KLVM, K6S0, K3HT) could see low clouds linger through tonight (10 to 50 percent chance) and the development of isolated fog into Saturday morning. While the breezy winds around and west of KBIL will taper off tonight, winds around KSHR, KMLS, and KBHK look to remain breezy this evening into tonight out of the southeast. With that said, uncertainty remains on the strength and duration of these winds at the surface as the inversion develops tonight. Arends

PRELIMINARY POINT TEMP/POPS

Sat Sun Mon Tue Wed Thu Fri ----------------------------------------------------------- BIL 038/072 044/075 044/054 038/069 047/064 042/072 045/076 01/B 26/T +8/W 21/B 64/W 21/U 00/U LVM 036/069 041/069 040/053 037/064 040/061 037/071 041/073 12/T 18/T +8/W 03/W 64/W 11/U 01/U HDN 038/072 042/077 042/054 035/069 045/064 040/071 042/077 01/B 25/T +9/W 21/B 65/W 21/B 00/U MLS 042/073 043/078 046/056 035/068 046/065 041/070 043/077 00/B 22/T 98/W 11/B 44/W 11/U 00/U 4BQ 043/073 045/078 046/053 036/065 045/062 041/067 043/074 01/B 12/T 89/W 20/B 34/W 11/U 00/U BHK 040/065 041/078 043/052 029/064 041/063 036/067 038/073 11/N 12/T 88/W 20/U 33/W 11/U 00/U SHR 035/069 041/076 040/050 031/066 039/058 035/068 037/073 11/B 13/T 8+/W 31/U 46/W 31/B 01/U

BYZ WATCHES/WARNINGS/ADVISORIES
MT...Winter Storm Watch in effect from Sunday evening through Monday afternoon FOR ZONES 67-68.
WY...None.