Montana Weekly Briefing - 15 July 2013

If you are watching this after Monday, then you may wish to check the NWS webpage or call any of the Montana NWS offices for updates as conditions may have changed. A weather disturbance moving across southern Saskatchewan will cause scattered thunderstorms to form over far northeastern Montana this afternoon. The greatest threat for isolated severe thunderstorms producing locally heavy rain, large hail, and damaging wind gusts will be north of the Missouri River and east of Glasgow. A moist southwest flow with weak upper level winds will generate scattered slow moving thunderstorms over the higher terrain of western Montana on Tuesday and Wednesday. Locally heavy rain is expected with these thunderstorms. Accumulating small hail is possible, as is flash flooding over recent burn areas, steep and rocky terrain, and roadway low spots such as creek crossings. General thunderstorm activity this week is expected to generate less than one-tenth of an inch of rainfall over most of the state, although amounts of around one-quarter to one-half inch are expected with stronger thunderstorms over the southwest and northeast. However, note that a single thunderstorm can quickly produce locally heavy rainfall amounts. Mountain showers and thunderstorms are possible through the week, with mainly dry conditions for southeast Montana. Wildfire fuels continue to dry statewide. This map shows vegetation greenness is below the seasonal normal across much of central and southern Montana. Fire danger is rated Moderate to High according to the US Forest Service Wildland Fire Assessment System. Looking ahead through the end of July, the Climate Prediction Center outlook indicates equal chances for near, above, or below normal temperatures. The outlook also indicates slightly better chances that precipitation will be drier than normal west of the Continental divide, and up to a 40 percent chance that precipitation will be above average across northeast Montana. In summary, it's summer in Montana. General thunderstorms are possible throughout the week, with otherwise warm and dry conditions prevailing as is typical for the season. However, the most hazardous thunderstorms will be over northeast Montana later today with the possibility of large hail and damaging wind gusts. On Tuesday and Wednesday the more hazardous storms will be over western and southwest Montana as slow moving wet thunderstorms may produce heavy rain and possible flash flooding. If you have any questions or concerns, contact any of the four Montana NWS offices. We are available all hours of every day.