A snowstorm weather forecast brought unseasonal snow to parts of Idaho, Montana and Wyoming on Sunday, with snow falling as low as 1,800 metres. The same cold front will keep moving through the western US on Monday, when more snow is due and strong winds are set to shift north into Wyoming.
Temperatures from the Canadian border to California have been 5-10C below normal since Friday, and some parts farther north have been more than 10C below normal. The pattern began over the weekend as a strong cold front spread in from the northern Pacific and brought the first significant rainfall in weeks to several parts of the north-west US.
Idaho Montana Wyoming
Across the Rocky mountains in Idaho, Montana and Wyoming, the rain and cold produced snowfall at unusually low elevations for the time of year. Several inches are expected to accumulate at higher altitudes on Monday, but the lowest-elevation snow line was already down to 1,800 metres by Sunday.
People in Idaho, Montana and Wyoming are dealing with a weather shift that arrived quickly after several dry weeks. The cold front also adds to wildfire danger in the western US because lightning can ignite dry vegetation and wind can spread existing fires.
North-east heatwave
The same week brings a different risk farther east. A heatwave developing over the north-east ahead of the Fourth of July weekend is expected to push temperatures into the high 30s celsius across parts of the midwest and north-east.
Forecast models suggest highs could possibly reach 40C in New York, Philadelphia and Washington DC on Thursday and Friday, with night-time lows struggling to drop below the high 20s celsius. For readers in the western US, the practical change is immediate: snow and wind now, with the cold pattern expected to hold for much of the coming week.
