High Wind — Meagher, Montana

2020-10-13 · Meagher, Montana

Event narrative

Mesonet station k7s6 3.6 s white sulphur springs (gtfwfo).

Wider weather episode

Strong westerly flow aloft delivered gusty westerly surface winds, along with scattered showers and mountain snow along the Divide and over portions of Central/North-central Montana on Monday October 12th. In addition, a few of these showers produced some lightning strikes along with moderate downpours of rain. This activity was expected to continue into the evening hours, before diminishing with the loss of daytime heating. The High Wind warning was continued due to sustained winds and gusts remained within striking distance of criteria values. There was a brief period of quiet weather as

transient ridging quickly traversed the region Monday night. The first sign of

the next weather maker was felt along the Divide Tuesday morning as a brief period of accumulating snow developed for locations above 5000 ft. The Winter Weather Advisory still looked good as of Monday afternoon as it appeared there could be some impacts to travel and outdoor interests before the warmer air moves in and inhibited snow accumulation. This area of precipitation then moved over the remainder of the CWA by Tuesday afternoon but snow levels were expected to rise above 7000 ft by afternoon.

The focus then began to shift toward the potential strong winds from Tuesday afternoon into Wednesday morning as a wide swath of very strong upper level winds move into North-central and Southwest Montana. There was still some uncertainty on Monday whether these winds would translate to the surface wind gusts in excess of 60 mph, but the possibility looked best over the higher terrain. The area of greatest concern was areas south and west of a Lewistown, to Great Falls, to Cut Bank line where the strongest H700 winds of 50-70kts were expected to reside through Wednesday morning; which had the potential to make travel over mountain passes like MacDonald, Bozeman, Norris Hill, and Deep Creek hazardous as this looked like an ideal setup for high winds to materialize given a strong west- to-east flow. Given the situation, the current High Wind Watch was continued. Late Tuesday night into Wednesday morning, snow levels began to fall once again as colder air filled in on the back side of the system. This is when some lower elevation locations had the potential to see some light

accumulating snow over portions of North-central Montana, in addition to locations along the divide and the Central Mountains. Snowfall accumulations of 3-6 appeared possible along the Continental Divide and in the mountains of Central and North

Central Montana during the day on Wednesday, with even a dusting to up upwards of 2 over portions of the plains. especially along the Montana Hwy 200 corridor. A Winter Weather Advisory was issued on Tuesday for this snow. In addition to precipitation, another bout of high wind criteria wind speeds/gusts occurred during the morning and early afternoon hours across nearly the entire CWA (save for the Hi-Line east of Shelby) on Wednesday. Some mountain snow did occur Wednesday night that was reported early Thursday morning.

Source: NOAA Storm Events Database, event_id 921358. Narrative written by the NWS forecast office that issued the report.