Rainfall warning and high stream flow advisory continues for Nelson and West Kootenay
By Timothy Schafer
Note: Warning is now over.
A rainfall warning has been upgraded and extended for Nelson and the West Kootenay region, prompting the BC River Forecast Centre to usher in a high stream flow advisory for the Kootenay and Kettle regions.
Around 35 millimetres of rain is expected by Friday morning in the Nelson region, warned Environment Canada, as a moist low pressure system moved into the Kootenay region Wednesday night.
That extra moisture has created a high stream flow advisory for the Kettle-Boundary and the Kootenay regions, as well as a flood watch in place for the West Kettle River, the Kettle River and the Moyie River (Yahk).
River levels in the region have been rising or flowing high for the past two weeks, a Centre report stated, due to the onset of the spring snow melt. The low pressure system in the Kootenays means temperatures will be low, however, and the snow melt will be limited.
Although river levels are currently below their two-year level, river levels across the region are expected to rise Thursday and into Friday in response to the rainfall.
The low pressure system is expected to remain stationary over the region tonight and into Friday morning — erasing an earlier prediction of a partly cloudy, but dry, start to the weekend.
Through Thursday and into Friday the city will see rain, heavy at times, that will give way as Friday wears on.
This news isn’t welcome for anyone living near a waterway, with Kootenay rivers, creeks and streams all flowing at their peak, with nit much room left to accommodate more moisture.
A low pressure system
A low pressure area is commonly associated with inclement weather, while high pressure areas are associated with light winds and fair skies.
Wind is initially accelerated from areas of high pressure to areas of low pressure. This is due to density (or temperature and moisture) differences between two air masses.
Since stronger high pressure systems contain cooler or drier air, the air mass is more dense and flows towards areas that are warm or moist, which are in the vicinity of low pressure areas in advance of their associated cold fronts.
The stronger the pressure difference between a high pressure system and a low pressure system, the stronger the wind.
Advisories and watches
A high stream flow advisory means that river levels are rising or expected to rise rapidly, but that no major flooding is expected. Minor flooding in low-lying areas is possible.
A flood watch means that river levels are rising and will approach or may exceed the banks. Flooding of areas adjacent to affected rivers may occur.
Comments