Boyd, MT 59013 Weather

Key messages

- Patchy fog this morning and Friday morning.

- Mostly dry with seasonable temperatures today into Saturday.

- A weather system may bring cooler temperatures, precipitation, and windy conditions to the region Sunday into Monday, though uncertainty remains.

Update

Fog continues to expand on satellite imagery along the Musselshell east of Harlowton, and we recently received a report of very poor visibility in Roundup. Have issued a Dense Fog Advisory until 10am for Musselshell and Golden Valley Counties. Temps are below freezing and some roads and sidewalks could be a bit icy as well. Further south, we are also seeing more localized fog form along the Yellowstone from Billings to Custer, and the Bighorn from Hardin northward. Though there are no cameras to confirm at this time, some of this fog is probably locally dense. A heads up for folks during their morning commute in these areas. JKL

Discussion

Today through Wednesday:

Cool temperatures, light winds, and dew point depressions near zero may result in patchy fog early this morning, especially along the Musselshell and lower Yellowstone River valleys (20 percent chance). Any fog that does develop should lift after sunrise, giving way to a mild and dry day with high temperatures in the 50s to lower 60s. While winds will be lighter today than yesterday, expect winds to shift and strengthen out of the northeast and east through the day. With this, peak wind gusts around 10 to 20 mph are forecast, strongest around Livingston. As the winds subside tonight, cool temperatures and low dew point depressions may result in another round of patchy fog across south-central and eastern Montana (20 percent chance). Any fog that develops is expected to lift around to a little after sunrise on Friday.

Friday into Saturday will remain mild and mainly dry, though the chance of precipitation does begin to increase over/near the mountains as higher atmospheric moisture content and a few waves of energy move through the region from the south. This is associated with the low pressure system that is expected to be developing off the west coast of the United States. While winds will be breezy out of the southeast in eastern Montana on Friday, generally light winds are expected on Saturday.

Sunday into Monday, the previously mentioned low pressure system is expected to move onshore and through our region in some fashion, though uncertainty remains in the evolution of this system over our region. With that said, there is at least a chance of seeing brief cooler temperatures, precipitation, and windy conditions over our area as this system moves through. At this time, the chance of seeing a half inch (0.50") or more of precipitation (rain and melted snow) is medium over the foothills of southern Montana and northern Wyoming and the plains of far south- eastern Montana, and high over the mountains of southern Montana and northern Wyoming. As far as precipitation type goes, ensembles have been consistent showing this system being too warm, in most solutions, for snow over the plains. With that said, dynamic cooling and/or precipitation occurring at night could still allow for snow over some of the higher hills in south- eastern Montana and northern Wyoming (low chance). Otherwise, temperatures will still be cool enough for snow in the mountains. For wind, the National Blend of Models (NBM) is currently advertising wind gusts in the 20s to 40s mph, with a low chance of 50 mph or greater wind gusts.

Mainly dry conditions look to return Tuesday into Wednesday next week, though a cold front may bring a brief shot of light precipitation through the area late Tuesday into early Wednesday (overall low chance). LA

Aviation

12z Update. Fog has formed along portions of the Yellowstone, Musselshell and Bighorn River valleys. This is most notable along the Musselshell but just recently we are seeing more localized fog near KBIL and K00U. For KBIL, expect erratic fluctuations in ceilings and visibility thru ~15z. KMLS may also see brief visibility reductions. Once the fog dissipates (by ~17z), VFR will prevail through the day. There is potential for fog & low stratus again tonight, over a larger area. This will be something to monitor today. JKL

Preliminary point temp/pops

Tdy Fri Sat Sun Mon Tue Wed ------------------------------------------------------- BIL 053 032/047 032/058 036/053 039/052 034/057 034/054 0/U 00/B 00/B 04/W 84/W 10/U 00/B LVM 054 026/051 029/058 033/050 028/048 025/056 027/054 0/U 00/B 01/B 16/W 83/W 10/U 01/B HDN 056 028/053 028/059 031/057 034/052 028/059 029/056 0/U 00/B 00/B 02/W 86/W 21/U 11/B MLS 054 030/057 036/057 036/061 039/051 031/056 032/052 0/U 00/B 00/B 01/E 66/W 31/B 11/B 4BQ 058 033/058 038/059 037/063 039/048 032/054 033/053 0/U 00/B 00/B 01/E 77/W 41/B 10/B BHK 057 026/054 038/062 037/064 037/051 029/054 029/053 0/U 00/N 10/E 01/E 78/W 51/B 11/U SHR 058 027/054 030/059 031/058 032/049 027/057 029/055 0/U 00/B 11/B 04/W 86/W 31/U 11/B

Watches, warnings and advisories

MT: Dense Fog Advisory in effect until 10 AM MDT this morning FOR ZONES 29-42. WY: None.