High Wind — Jefferson, Montana

2020-06-13 · Jefferson, Montana

Event narrative

Mesonet station mtbou, Boulder Hill (mt dot). Station elevation: 5592 ft.

Wider weather episode

With respect to wind, south to north orientated H700 jet max of 35-50kts/H500 jet max of 50-75kts remains over southwest and into central Montana through 03-06z Sunday before sliding eastward over The Northern High Plains. Deep diurnal mixing combined with terrain funneling, most notably in the north-south orientated valleys, continues to lead to sustained winds of 35-45 mph and gusts approaching 65 mph across southwest and into portions of central Montana. High Wind Warning continues for Beaverhead,

Madison, Gallatin, Jefferson, and Broadwater counties. While a few isolated wind gusts above High Wind criteria occur north of the High Wind Warning in Central Montana (Porphyry Peak in the Little Belt Mountains and Judith Peak in the Judith Mountains), have held off on expanding the High Wind Warning further north given the isolated nature of the gusts. With that being said, concern is that the H700/500 jet max slides further north between 21z Saturday and 03z Sunday that locations like Great Falls, Belt, and Stanford could briefly reach High Wind criteria.

With respect to the potential for severe weather, the Storm Prediction Center continues to maintain a slight risk for portions of northwest Montana, mainly northwest of a line from Augusta, to Choteau, to Conrad, to Cut Bank. Afternoon storms are on-going across western Montana, with additional development expected along The Continental Divide through 00z Sunday. Hi-Res models also indicate the potential for storms to develop over far eastern portions of central and north central Montana before lifting north/northeast into southern Canada, but confidence in coverage and intensity of these storms is not as high as across northwest Montana. Large hail up to the size

of half dollar and damaging winds up to 60 mph are the primary threats with any severe thunderstorm, especially across the Slight Risk area. In addition to the threat for

severe weather, the potential for locally heavy rainfall leading to flash flooding also exists, especially where storms train over complex terrain.

Source: NOAA Storm Events Database, event_id 906067. Narrative written by the NWS forecast office that issued the report.