A large temperature differential developing across North America later this week, brought about by significant large-scale mid-level troughing, is expected to bring widespread unsettled – and potentially extreme – weather conditions.
Spanning a distance of about 500 miles across the northern Great Plains and Mississippi basin, temperatures could range from more than 10C above average in the east, to more than 10C below average in the west. At this stage it is uncertain as to where the significant temperature boundary will lie, but a single state could see maximum daytime temperatures range from 25C in the east to barely scraping 0C farther west.
Through Friday and this weekend, an area of low pressure will deepen rapidly, tracking north-eastwards. The notable thermal differential will encourage the development of widespread strong winds with gusts that could reach 50-70mph across central parts of the US.
In addition, the associated cold front may allow for the development of severe thunderstorms, the risk gradually pushing farther north and east through the weekend as the pressure-centre shifts. These thunderstorms could be accompanied by torrential rain, large hail and tornadic activity.
The Northern Plains are also likely to get significant snow accumulations where the frigid air remains. At this range, the development of the system going into next week is still uncertain, especially at local levels.
On the other side of the Pacific, large temperature contrasts will also be at play this week and early next. Significant warmth across parts of north-east China, Korea and Japan will continue for the remainder of this week. Temperatures of up to 10C above the April average look likely, with areas such as central Japan, more used to maximum temperatures of 15-18C in mid-April, possibly experiencing temperatures rising into the high 20s instead.
However, forecast models are indicating that the warmth is unlikely to last, with a strong cold front surging eastwards early next week, bringing with it heavy rain and strong winds. Behind this, a significant drop in temperature looks likely. Some places, particularly across north-east China, may experience a return of night-frost in places where daytime temperatures were around 30C just a couple of days earlier.
