textproduct: Billings

KEY MESSAGES

- Above normal temperatures continue through the week. Strong and gusty winds along the western foothills through this afternoon.

- Active period of weather today into next week. Heavy mountain snowfall is expected through Monday.

- High temperatures around normal in the forecast, Monday through Wednesday.

DISCUSSION

Today through Friday Night...

Precipitation: A shortwave moving from west to east will bring a 20-40% chance for rain/snow showers over lower elevations, a 60-80% chance of snow over the Beartooth/Absarokas, and a 40-60% chance of snow over the Bighorns today. Overall, precipitation totals are expected to remain light, with a less than 10% chance of 0.1" outside of the mountains. The greatest snow totals will be over the Beartooth/Absarokas, with a 70% chance of at least 4 inches of snow over west and southwest facing aspects. For Friday, precipitation is expected to remain mostly over the mountains and higher foothills, with the greatest snowfall totals again expected over the Beartooth/Absarokas. Currently, there is a 60% chance of at least another 4 inches of snow Friday over the west and southwest aspects.

Winds: A favorable pressure gradient and 700 mb winds increasing to 35-45 kts this morning suggest strong gap flow winds over the Livingston and Nye areas. Currently, gusts to around 65 mph are expected, with an 85% chance of gusts of at least 60 mph. A Wind Advisory is in effect for the Livingston area and Beartooth foothills through 2 PM today. For Friday, winds over the same area are expected to be lighter but still strong, with gusts around 35-45 mph.

Temperatures today and Friday will be around 10 degrees above normal, with highs in the 40s. Archer

Saturday through Thursday...

One last day of strong winds along the foothills west of Billings is in store on Saturday before that area (especially around Livingston) finally see a break for at least the first half of next week. Once again a strong pressure gradient is progged to be in place across south-central Montana on Saturday, giving Livingston area a 75% chance to see gusts reach at least 50 mph. As the gradient shifts throughout the day due to a strong jet crossing the area, odds of higher winds shifts more favorably towards Big Timber and Harlowton, who have a 60% chance to see gusts exceed 50 mph. Winds will slowly decrease Saturday evening into the night.

During this period and into Sunday, the Beartooths will continue to see 1-5 inches of snow per day. Though higher amounts will be specific to west facing slopes and the Cooke City area (northeast facing slopes, including Red Loge Mountain, won't see much during this period.

That said, this changes beginning late Sunday and through Monday as we have high confidence in a trough and stream of Pacific moisture moving into the area. On top of an abundance of moisture moving into the area, guidance has been specific on getting upslope (north to northeast) low-level flow into south-central MT, assisting in precipitation potential across the area. For the lower elevations, precip type will likely start as rain before at some point switching over to snow due to cold air advection, while the mountains will see a steady stream of snow the entire time. there is a 70-90% chance for the Beartooths to see at least 10" of snow Sunday through Monday. Lower elevation potential is harder to broadly pinpoint, as with the switch from rain to snow being gradual, snow potential is highly dependent on elevation. For example, city of Billings getting an inch or less (not the official forecast) while the hills just south of town get 2-4 inches. A lot of uncertainty in snow amounts, but confidence is high for a wet system to take place that will usher in temperatures that bring them back down to near-normal values (mid 30s). Vertz

AVIATION

Wind gusts to around 50 kts are expected near KLVM through this afternoon. Scattered snow showers are possible near KLVM, with isolated rain/snow showers possible at all other TAF sites, see expected timing below. Expect occasional mountain obscuration. Archer

SITE TIMING ----------------- KLVM 14Z-02Z KBIL 17Z-22Z KSHR 20Z-23Z KMLS 00Z-03Z

PRELIMINARY POINT TEMP/POPS

Tdy Fri Sat Sun Mon Tue Wed ------------------------------------------------------- BIL 044 029/046 030/047 031/044 029/038 023/036 019/035 3/W 00/B 22/O 23/O 85/S 22/S 10/B LVM 044 029/043 032/046 031/045 028/038 020/035 016/037 4/W 12/J 53/O 36/O 95/S 11/B 11/B HDN 043 026/048 027/047 030/046 029/038 022/035 016/035 3/W 10/U 22/R 22/O 87/S 43/S 21/B MLS 041 028/047 024/046 028/044 024/033 019/029 014/030 1/B 20/U 01/B 10/B 55/S 22/S 00/B 4BQ 044 029/047 026/047 031/045 027/035 022/032 017/033 1/B 20/U 00/B 10/B 56/S 21/B 10/B BHK 045 025/045 021/044 024/042 019/030 012/026 010/028 0/B 20/U 00/B 00/B 34/S 21/E 00/B SHR 044 023/047 023/047 025/047 024/036 016/035 011/036 2/W 11/U 11/B 11/B 77/S 32/S 10/B

BYZ WATCHES/WARNINGS/ADVISORIES

MT...Wind Advisory in effect until 2 PM MST this afternoon FOR ZONES 65-66. WY...None.